Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* |
Davide Libenzi | 5071f97 | 2009-03-31 15:24:10 -0700 | [diff] [blame] | 2 | * fs/eventpoll.c (Efficient event retrieval implementation) |
| 3 | * Copyright (C) 2001,...,2009 Davide Libenzi |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4 | * |
| 5 | * This program is free software; you can redistribute it and/or modify |
| 6 | * it under the terms of the GNU General Public License as published by |
| 7 | * the Free Software Foundation; either version 2 of the License, or |
| 8 | * (at your option) any later version. |
| 9 | * |
| 10 | * Davide Libenzi <davidel@xmailserver.org> |
| 11 | * |
| 12 | */ |
| 13 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 14 | #include <linux/init.h> |
| 15 | #include <linux/kernel.h> |
| 16 | #include <linux/sched.h> |
| 17 | #include <linux/fs.h> |
| 18 | #include <linux/file.h> |
| 19 | #include <linux/signal.h> |
| 20 | #include <linux/errno.h> |
| 21 | #include <linux/mm.h> |
| 22 | #include <linux/slab.h> |
| 23 | #include <linux/poll.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 24 | #include <linux/string.h> |
| 25 | #include <linux/list.h> |
| 26 | #include <linux/hash.h> |
| 27 | #include <linux/spinlock.h> |
| 28 | #include <linux/syscalls.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 29 | #include <linux/rbtree.h> |
| 30 | #include <linux/wait.h> |
| 31 | #include <linux/eventpoll.h> |
| 32 | #include <linux/mount.h> |
| 33 | #include <linux/bitops.h> |
Arjan van de Ven | 144efe3 | 2006-03-23 03:00:32 -0800 | [diff] [blame] | 34 | #include <linux/mutex.h> |
Davide Libenzi | da66f7c | 2007-05-10 22:23:21 -0700 | [diff] [blame] | 35 | #include <linux/anon_inodes.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 36 | #include <asm/uaccess.h> |
| 37 | #include <asm/system.h> |
| 38 | #include <asm/io.h> |
| 39 | #include <asm/mman.h> |
Arun Sharma | 6006349 | 2011-07-26 16:09:06 -0700 | [diff] [blame] | 40 | #include <linux/atomic.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 41 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 42 | /* |
| 43 | * LOCKING: |
| 44 | * There are three level of locking required by epoll : |
| 45 | * |
Arjan van de Ven | 144efe3 | 2006-03-23 03:00:32 -0800 | [diff] [blame] | 46 | * 1) epmutex (mutex) |
Davide Libenzi | c7ea763 | 2007-05-15 01:40:47 -0700 | [diff] [blame] | 47 | * 2) ep->mtx (mutex) |
| 48 | * 3) ep->lock (spinlock) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 49 | * |
| 50 | * The acquire order is the one listed above, from 1 to 3. |
| 51 | * We need a spinlock (ep->lock) because we manipulate objects |
| 52 | * from inside the poll callback, that might be triggered from |
| 53 | * a wake_up() that in turn might be called from IRQ context. |
| 54 | * So we can't sleep inside the poll callback and hence we need |
| 55 | * a spinlock. During the event transfer loop (from kernel to |
| 56 | * user space) we could end up sleeping due a copy_to_user(), so |
| 57 | * we need a lock that will allow us to sleep. This lock is a |
Davide Libenzi | d47de16 | 2007-05-15 01:40:41 -0700 | [diff] [blame] | 58 | * mutex (ep->mtx). It is acquired during the event transfer loop, |
| 59 | * during epoll_ctl(EPOLL_CTL_DEL) and during eventpoll_release_file(). |
| 60 | * Then we also need a global mutex to serialize eventpoll_release_file() |
| 61 | * and ep_free(). |
| 62 | * This mutex is acquired by ep_free() during the epoll file |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 63 | * cleanup path and it is also acquired by eventpoll_release_file() |
| 64 | * if a file has been pushed inside an epoll set and it is then |
Daniel Baluta | bf6a41d | 2011-01-30 23:42:29 +0200 | [diff] [blame] | 65 | * close()d without a previous call to epoll_ctl(EPOLL_CTL_DEL). |
Davide Libenzi | 22bacca | 2011-02-25 14:44:12 -0800 | [diff] [blame] | 66 | * It is also acquired when inserting an epoll fd onto another epoll |
| 67 | * fd. We do this so that we walk the epoll tree and ensure that this |
| 68 | * insertion does not create a cycle of epoll file descriptors, which |
| 69 | * could lead to deadlock. We need a global mutex to prevent two |
| 70 | * simultaneous inserts (A into B and B into A) from racing and |
| 71 | * constructing a cycle without either insert observing that it is |
| 72 | * going to. |
Nelson Elhage | d8805e6 | 2011-10-31 17:13:14 -0700 | [diff] [blame] | 73 | * It is necessary to acquire multiple "ep->mtx"es at once in the |
| 74 | * case when one epoll fd is added to another. In this case, we |
| 75 | * always acquire the locks in the order of nesting (i.e. after |
| 76 | * epoll_ctl(e1, EPOLL_CTL_ADD, e2), e1->mtx will always be acquired |
| 77 | * before e2->mtx). Since we disallow cycles of epoll file |
| 78 | * descriptors, this ensures that the mutexes are well-ordered. In |
| 79 | * order to communicate this nesting to lockdep, when walking a tree |
| 80 | * of epoll file descriptors, we use the current recursion depth as |
| 81 | * the lockdep subkey. |
Davide Libenzi | d47de16 | 2007-05-15 01:40:41 -0700 | [diff] [blame] | 82 | * It is possible to drop the "ep->mtx" and to use the global |
| 83 | * mutex "epmutex" (together with "ep->lock") to have it working, |
| 84 | * but having "ep->mtx" will make the interface more scalable. |
Arjan van de Ven | 144efe3 | 2006-03-23 03:00:32 -0800 | [diff] [blame] | 85 | * Events that require holding "epmutex" are very rare, while for |
Davide Libenzi | d47de16 | 2007-05-15 01:40:41 -0700 | [diff] [blame] | 86 | * normal operations the epoll private "ep->mtx" will guarantee |
| 87 | * a better scalability. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 88 | */ |
| 89 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 90 | /* Epoll private bits inside the event mask */ |
| 91 | #define EP_PRIVATE_BITS (EPOLLONESHOT | EPOLLET) |
| 92 | |
Davide Libenzi | 5071f97 | 2009-03-31 15:24:10 -0700 | [diff] [blame] | 93 | /* Maximum number of nesting allowed inside epoll sets */ |
| 94 | #define EP_MAX_NESTS 4 |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 95 | |
Davide Libenzi | b611967 | 2006-10-11 01:21:44 -0700 | [diff] [blame] | 96 | #define EP_MAX_EVENTS (INT_MAX / sizeof(struct epoll_event)) |
| 97 | |
Davide Libenzi | d47de16 | 2007-05-15 01:40:41 -0700 | [diff] [blame] | 98 | #define EP_UNACTIVE_PTR ((void *) -1L) |
| 99 | |
Davide Libenzi | 7ef9964 | 2008-12-01 13:13:55 -0800 | [diff] [blame] | 100 | #define EP_ITEM_COST (sizeof(struct epitem) + sizeof(struct eppoll_entry)) |
| 101 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 102 | struct epoll_filefd { |
| 103 | struct file *file; |
| 104 | int fd; |
| 105 | }; |
| 106 | |
| 107 | /* |
Davide Libenzi | 5071f97 | 2009-03-31 15:24:10 -0700 | [diff] [blame] | 108 | * Structure used to track possible nested calls, for too deep recursions |
| 109 | * and loop cycles. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 110 | */ |
Davide Libenzi | 5071f97 | 2009-03-31 15:24:10 -0700 | [diff] [blame] | 111 | struct nested_call_node { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 112 | struct list_head llink; |
Davide Libenzi | 5071f97 | 2009-03-31 15:24:10 -0700 | [diff] [blame] | 113 | void *cookie; |
Davide Libenzi | 3fe4a97 | 2009-06-17 16:25:58 -0700 | [diff] [blame] | 114 | void *ctx; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 115 | }; |
| 116 | |
| 117 | /* |
Davide Libenzi | 5071f97 | 2009-03-31 15:24:10 -0700 | [diff] [blame] | 118 | * This structure is used as collector for nested calls, to check for |
| 119 | * maximum recursion dept and loop cycles. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 120 | */ |
Davide Libenzi | 5071f97 | 2009-03-31 15:24:10 -0700 | [diff] [blame] | 121 | struct nested_calls { |
| 122 | struct list_head tasks_call_list; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 123 | spinlock_t lock; |
| 124 | }; |
| 125 | |
| 126 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 127 | * Each file descriptor added to the eventpoll interface will |
Davide Libenzi | 6192bd5 | 2007-05-08 00:25:41 -0700 | [diff] [blame] | 128 | * have an entry of this type linked to the "rbr" RB tree. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 129 | */ |
| 130 | struct epitem { |
Davide Libenzi | 67647d0 | 2007-05-15 01:40:52 -0700 | [diff] [blame] | 131 | /* RB tree node used to link this structure to the eventpoll RB tree */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 132 | struct rb_node rbn; |
| 133 | |
| 134 | /* List header used to link this structure to the eventpoll ready list */ |
| 135 | struct list_head rdllink; |
| 136 | |
Davide Libenzi | c7ea763 | 2007-05-15 01:40:47 -0700 | [diff] [blame] | 137 | /* |
| 138 | * Works together "struct eventpoll"->ovflist in keeping the |
| 139 | * single linked chain of items. |
| 140 | */ |
| 141 | struct epitem *next; |
| 142 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 143 | /* The file descriptor information this item refers to */ |
| 144 | struct epoll_filefd ffd; |
| 145 | |
| 146 | /* Number of active wait queue attached to poll operations */ |
| 147 | int nwait; |
| 148 | |
| 149 | /* List containing poll wait queues */ |
| 150 | struct list_head pwqlist; |
| 151 | |
| 152 | /* The "container" of this item */ |
| 153 | struct eventpoll *ep; |
| 154 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 155 | /* List header used to link this item to the "struct file" items list */ |
| 156 | struct list_head fllink; |
Davide Libenzi | d47de16 | 2007-05-15 01:40:41 -0700 | [diff] [blame] | 157 | |
Davide Libenzi | c7ea763 | 2007-05-15 01:40:47 -0700 | [diff] [blame] | 158 | /* The structure that describe the interested events and the source fd */ |
| 159 | struct epoll_event event; |
Davide Libenzi | d47de16 | 2007-05-15 01:40:41 -0700 | [diff] [blame] | 160 | }; |
| 161 | |
| 162 | /* |
| 163 | * This structure is stored inside the "private_data" member of the file |
Daniel Baluta | bf6a41d | 2011-01-30 23:42:29 +0200 | [diff] [blame] | 164 | * structure and represents the main data structure for the eventpoll |
Davide Libenzi | d47de16 | 2007-05-15 01:40:41 -0700 | [diff] [blame] | 165 | * interface. |
| 166 | */ |
| 167 | struct eventpoll { |
Daniel Baluta | bf6a41d | 2011-01-30 23:42:29 +0200 | [diff] [blame] | 168 | /* Protect the access to this structure */ |
Davide Libenzi | c7ea763 | 2007-05-15 01:40:47 -0700 | [diff] [blame] | 169 | spinlock_t lock; |
Davide Libenzi | d47de16 | 2007-05-15 01:40:41 -0700 | [diff] [blame] | 170 | |
| 171 | /* |
| 172 | * This mutex is used to ensure that files are not removed |
| 173 | * while epoll is using them. This is held during the event |
| 174 | * collection loop, the file cleanup path, the epoll file exit |
| 175 | * code and the ctl operations. |
| 176 | */ |
| 177 | struct mutex mtx; |
| 178 | |
| 179 | /* Wait queue used by sys_epoll_wait() */ |
| 180 | wait_queue_head_t wq; |
| 181 | |
| 182 | /* Wait queue used by file->poll() */ |
| 183 | wait_queue_head_t poll_wait; |
| 184 | |
| 185 | /* List of ready file descriptors */ |
| 186 | struct list_head rdllist; |
| 187 | |
Davide Libenzi | 67647d0 | 2007-05-15 01:40:52 -0700 | [diff] [blame] | 188 | /* RB tree root used to store monitored fd structs */ |
Davide Libenzi | d47de16 | 2007-05-15 01:40:41 -0700 | [diff] [blame] | 189 | struct rb_root rbr; |
| 190 | |
| 191 | /* |
| 192 | * This is a single linked list that chains all the "struct epitem" that |
Lucas De Marchi | 25985ed | 2011-03-30 22:57:33 -0300 | [diff] [blame] | 193 | * happened while transferring ready events to userspace w/out |
Davide Libenzi | d47de16 | 2007-05-15 01:40:41 -0700 | [diff] [blame] | 194 | * holding ->lock. |
| 195 | */ |
| 196 | struct epitem *ovflist; |
Davide Libenzi | 7ef9964 | 2008-12-01 13:13:55 -0800 | [diff] [blame] | 197 | |
| 198 | /* The user that created the eventpoll descriptor */ |
| 199 | struct user_struct *user; |
Jason Baron | 28d82dc | 2012-01-12 17:17:43 -0800 | [diff] [blame] | 200 | |
| 201 | struct file *file; |
| 202 | |
| 203 | /* used to optimize loop detection check */ |
| 204 | int visited; |
| 205 | struct list_head visited_list_link; |
Davide Libenzi | d47de16 | 2007-05-15 01:40:41 -0700 | [diff] [blame] | 206 | }; |
| 207 | |
| 208 | /* Wait structure used by the poll hooks */ |
| 209 | struct eppoll_entry { |
| 210 | /* List header used to link this structure to the "struct epitem" */ |
| 211 | struct list_head llink; |
| 212 | |
| 213 | /* The "base" pointer is set to the container "struct epitem" */ |
Tony Battersby | 4f0989d | 2009-03-31 15:24:16 -0700 | [diff] [blame] | 214 | struct epitem *base; |
Davide Libenzi | d47de16 | 2007-05-15 01:40:41 -0700 | [diff] [blame] | 215 | |
| 216 | /* |
| 217 | * Wait queue item that will be linked to the target file wait |
| 218 | * queue head. |
| 219 | */ |
| 220 | wait_queue_t wait; |
| 221 | |
| 222 | /* The wait queue head that linked the "wait" wait queue item */ |
| 223 | wait_queue_head_t *whead; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 224 | }; |
| 225 | |
| 226 | /* Wrapper struct used by poll queueing */ |
| 227 | struct ep_pqueue { |
| 228 | poll_table pt; |
| 229 | struct epitem *epi; |
| 230 | }; |
| 231 | |
Davide Libenzi | 5071f97 | 2009-03-31 15:24:10 -0700 | [diff] [blame] | 232 | /* Used by the ep_send_events() function as callback private data */ |
| 233 | struct ep_send_events_data { |
| 234 | int maxevents; |
| 235 | struct epoll_event __user *events; |
| 236 | }; |
| 237 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 238 | /* |
Davide Libenzi | 7ef9964 | 2008-12-01 13:13:55 -0800 | [diff] [blame] | 239 | * Configuration options available inside /proc/sys/fs/epoll/ |
| 240 | */ |
Davide Libenzi | 7ef9964 | 2008-12-01 13:13:55 -0800 | [diff] [blame] | 241 | /* Maximum number of epoll watched descriptors, per user */ |
Robin Holt | 52bd19f7 | 2011-01-12 17:00:01 -0800 | [diff] [blame] | 242 | static long max_user_watches __read_mostly; |
Davide Libenzi | 7ef9964 | 2008-12-01 13:13:55 -0800 | [diff] [blame] | 243 | |
| 244 | /* |
Davide Libenzi | d47de16 | 2007-05-15 01:40:41 -0700 | [diff] [blame] | 245 | * This mutex is used to serialize ep_free() and eventpoll_release_file(). |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 246 | */ |
Davide Libenzi | 7ef9964 | 2008-12-01 13:13:55 -0800 | [diff] [blame] | 247 | static DEFINE_MUTEX(epmutex); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 248 | |
Davide Libenzi | 22bacca | 2011-02-25 14:44:12 -0800 | [diff] [blame] | 249 | /* Used to check for epoll file descriptor inclusion loops */ |
| 250 | static struct nested_calls poll_loop_ncalls; |
| 251 | |
Davide Libenzi | 5071f97 | 2009-03-31 15:24:10 -0700 | [diff] [blame] | 252 | /* Used for safe wake up implementation */ |
| 253 | static struct nested_calls poll_safewake_ncalls; |
| 254 | |
| 255 | /* Used to call file's f_op->poll() under the nested calls boundaries */ |
| 256 | static struct nested_calls poll_readywalk_ncalls; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 257 | |
| 258 | /* Slab cache used to allocate "struct epitem" */ |
Christoph Lameter | e18b890 | 2006-12-06 20:33:20 -0800 | [diff] [blame] | 259 | static struct kmem_cache *epi_cache __read_mostly; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 260 | |
| 261 | /* Slab cache used to allocate "struct eppoll_entry" */ |
Christoph Lameter | e18b890 | 2006-12-06 20:33:20 -0800 | [diff] [blame] | 262 | static struct kmem_cache *pwq_cache __read_mostly; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 263 | |
Jason Baron | 28d82dc | 2012-01-12 17:17:43 -0800 | [diff] [blame] | 264 | /* Visited nodes during ep_loop_check(), so we can unset them when we finish */ |
| 265 | static LIST_HEAD(visited_list); |
| 266 | |
| 267 | /* |
| 268 | * List of files with newly added links, where we may need to limit the number |
| 269 | * of emanating paths. Protected by the epmutex. |
| 270 | */ |
| 271 | static LIST_HEAD(tfile_check_list); |
| 272 | |
Davide Libenzi | 7ef9964 | 2008-12-01 13:13:55 -0800 | [diff] [blame] | 273 | #ifdef CONFIG_SYSCTL |
| 274 | |
| 275 | #include <linux/sysctl.h> |
| 276 | |
Robin Holt | 52bd19f7 | 2011-01-12 17:00:01 -0800 | [diff] [blame] | 277 | static long zero; |
| 278 | static long long_max = LONG_MAX; |
Davide Libenzi | 7ef9964 | 2008-12-01 13:13:55 -0800 | [diff] [blame] | 279 | |
| 280 | ctl_table epoll_table[] = { |
| 281 | { |
Davide Libenzi | 7ef9964 | 2008-12-01 13:13:55 -0800 | [diff] [blame] | 282 | .procname = "max_user_watches", |
| 283 | .data = &max_user_watches, |
Robin Holt | 52bd19f7 | 2011-01-12 17:00:01 -0800 | [diff] [blame] | 284 | .maxlen = sizeof(max_user_watches), |
Davide Libenzi | 7ef9964 | 2008-12-01 13:13:55 -0800 | [diff] [blame] | 285 | .mode = 0644, |
Robin Holt | 52bd19f7 | 2011-01-12 17:00:01 -0800 | [diff] [blame] | 286 | .proc_handler = proc_doulongvec_minmax, |
Davide Libenzi | 7ef9964 | 2008-12-01 13:13:55 -0800 | [diff] [blame] | 287 | .extra1 = &zero, |
Robin Holt | 52bd19f7 | 2011-01-12 17:00:01 -0800 | [diff] [blame] | 288 | .extra2 = &long_max, |
Davide Libenzi | 7ef9964 | 2008-12-01 13:13:55 -0800 | [diff] [blame] | 289 | }, |
Eric W. Biederman | ab09203 | 2009-11-05 14:25:10 -0800 | [diff] [blame] | 290 | { } |
Davide Libenzi | 7ef9964 | 2008-12-01 13:13:55 -0800 | [diff] [blame] | 291 | }; |
| 292 | #endif /* CONFIG_SYSCTL */ |
| 293 | |
Jason Baron | 28d82dc | 2012-01-12 17:17:43 -0800 | [diff] [blame] | 294 | static const struct file_operations eventpoll_fops; |
| 295 | |
| 296 | static inline int is_file_epoll(struct file *f) |
| 297 | { |
| 298 | return f->f_op == &eventpoll_fops; |
| 299 | } |
Pekka Enberg | b030a4d | 2005-06-23 00:10:03 -0700 | [diff] [blame] | 300 | |
Davide Libenzi | 67647d0 | 2007-05-15 01:40:52 -0700 | [diff] [blame] | 301 | /* Setup the structure that is used as key for the RB tree */ |
Pekka Enberg | b030a4d | 2005-06-23 00:10:03 -0700 | [diff] [blame] | 302 | static inline void ep_set_ffd(struct epoll_filefd *ffd, |
| 303 | struct file *file, int fd) |
| 304 | { |
| 305 | ffd->file = file; |
| 306 | ffd->fd = fd; |
| 307 | } |
| 308 | |
Davide Libenzi | 67647d0 | 2007-05-15 01:40:52 -0700 | [diff] [blame] | 309 | /* Compare RB tree keys */ |
Pekka Enberg | b030a4d | 2005-06-23 00:10:03 -0700 | [diff] [blame] | 310 | static inline int ep_cmp_ffd(struct epoll_filefd *p1, |
| 311 | struct epoll_filefd *p2) |
| 312 | { |
| 313 | return (p1->file > p2->file ? +1: |
| 314 | (p1->file < p2->file ? -1 : p1->fd - p2->fd)); |
| 315 | } |
| 316 | |
Pekka Enberg | b030a4d | 2005-06-23 00:10:03 -0700 | [diff] [blame] | 317 | /* Tells us if the item is currently linked */ |
| 318 | static inline int ep_is_linked(struct list_head *p) |
| 319 | { |
| 320 | return !list_empty(p); |
| 321 | } |
| 322 | |
Oleg Nesterov | 971316f | 2012-02-24 20:07:29 +0100 | [diff] [blame] | 323 | static inline struct eppoll_entry *ep_pwq_from_wait(wait_queue_t *p) |
| 324 | { |
| 325 | return container_of(p, struct eppoll_entry, wait); |
| 326 | } |
| 327 | |
Pekka Enberg | b030a4d | 2005-06-23 00:10:03 -0700 | [diff] [blame] | 328 | /* Get the "struct epitem" from a wait queue pointer */ |
Davide Libenzi | cdac75e | 2008-04-29 00:58:34 -0700 | [diff] [blame] | 329 | static inline struct epitem *ep_item_from_wait(wait_queue_t *p) |
Pekka Enberg | b030a4d | 2005-06-23 00:10:03 -0700 | [diff] [blame] | 330 | { |
| 331 | return container_of(p, struct eppoll_entry, wait)->base; |
| 332 | } |
| 333 | |
| 334 | /* Get the "struct epitem" from an epoll queue wrapper */ |
Davide Libenzi | cdac75e | 2008-04-29 00:58:34 -0700 | [diff] [blame] | 335 | static inline struct epitem *ep_item_from_epqueue(poll_table *p) |
Pekka Enberg | b030a4d | 2005-06-23 00:10:03 -0700 | [diff] [blame] | 336 | { |
| 337 | return container_of(p, struct ep_pqueue, pt)->epi; |
| 338 | } |
| 339 | |
| 340 | /* Tells if the epoll_ctl(2) operation needs an event copy from userspace */ |
Davide Libenzi | 6192bd5 | 2007-05-08 00:25:41 -0700 | [diff] [blame] | 341 | static inline int ep_op_has_event(int op) |
Pekka Enberg | b030a4d | 2005-06-23 00:10:03 -0700 | [diff] [blame] | 342 | { |
| 343 | return op != EPOLL_CTL_DEL; |
| 344 | } |
| 345 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 346 | /* Initialize the poll safe wake up structure */ |
Davide Libenzi | 5071f97 | 2009-03-31 15:24:10 -0700 | [diff] [blame] | 347 | static void ep_nested_calls_init(struct nested_calls *ncalls) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 348 | { |
Davide Libenzi | 5071f97 | 2009-03-31 15:24:10 -0700 | [diff] [blame] | 349 | INIT_LIST_HEAD(&ncalls->tasks_call_list); |
| 350 | spin_lock_init(&ncalls->lock); |
| 351 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 352 | |
Davide Libenzi | 5071f97 | 2009-03-31 15:24:10 -0700 | [diff] [blame] | 353 | /** |
Davide Libenzi | 3fb0e58 | 2011-03-22 16:34:46 -0700 | [diff] [blame] | 354 | * ep_events_available - Checks if ready events might be available. |
| 355 | * |
| 356 | * @ep: Pointer to the eventpoll context. |
| 357 | * |
| 358 | * Returns: Returns a value different than zero if ready events are available, |
| 359 | * or zero otherwise. |
| 360 | */ |
| 361 | static inline int ep_events_available(struct eventpoll *ep) |
| 362 | { |
| 363 | return !list_empty(&ep->rdllist) || ep->ovflist != EP_UNACTIVE_PTR; |
| 364 | } |
| 365 | |
| 366 | /** |
Davide Libenzi | 5071f97 | 2009-03-31 15:24:10 -0700 | [diff] [blame] | 367 | * ep_call_nested - Perform a bound (possibly) nested call, by checking |
| 368 | * that the recursion limit is not exceeded, and that |
| 369 | * the same nested call (by the meaning of same cookie) is |
| 370 | * no re-entered. |
| 371 | * |
| 372 | * @ncalls: Pointer to the nested_calls structure to be used for this call. |
| 373 | * @max_nests: Maximum number of allowed nesting calls. |
| 374 | * @nproc: Nested call core function pointer. |
| 375 | * @priv: Opaque data to be passed to the @nproc callback. |
| 376 | * @cookie: Cookie to be used to identify this nested call. |
Davide Libenzi | 3fe4a97 | 2009-06-17 16:25:58 -0700 | [diff] [blame] | 377 | * @ctx: This instance context. |
Davide Libenzi | 5071f97 | 2009-03-31 15:24:10 -0700 | [diff] [blame] | 378 | * |
| 379 | * Returns: Returns the code returned by the @nproc callback, or -1 if |
| 380 | * the maximum recursion limit has been exceeded. |
| 381 | */ |
| 382 | static int ep_call_nested(struct nested_calls *ncalls, int max_nests, |
| 383 | int (*nproc)(void *, void *, int), void *priv, |
Davide Libenzi | 3fe4a97 | 2009-06-17 16:25:58 -0700 | [diff] [blame] | 384 | void *cookie, void *ctx) |
Davide Libenzi | 5071f97 | 2009-03-31 15:24:10 -0700 | [diff] [blame] | 385 | { |
| 386 | int error, call_nests = 0; |
| 387 | unsigned long flags; |
Davide Libenzi | 5071f97 | 2009-03-31 15:24:10 -0700 | [diff] [blame] | 388 | struct list_head *lsthead = &ncalls->tasks_call_list; |
| 389 | struct nested_call_node *tncur; |
| 390 | struct nested_call_node tnode; |
| 391 | |
| 392 | spin_lock_irqsave(&ncalls->lock, flags); |
| 393 | |
| 394 | /* |
| 395 | * Try to see if the current task is already inside this wakeup call. |
| 396 | * We use a list here, since the population inside this set is always |
| 397 | * very much limited. |
| 398 | */ |
| 399 | list_for_each_entry(tncur, lsthead, llink) { |
Davide Libenzi | 3fe4a97 | 2009-06-17 16:25:58 -0700 | [diff] [blame] | 400 | if (tncur->ctx == ctx && |
Davide Libenzi | 5071f97 | 2009-03-31 15:24:10 -0700 | [diff] [blame] | 401 | (tncur->cookie == cookie || ++call_nests > max_nests)) { |
| 402 | /* |
| 403 | * Ops ... loop detected or maximum nest level reached. |
| 404 | * We abort this wake by breaking the cycle itself. |
| 405 | */ |
Tony Battersby | abff55c | 2009-03-31 15:24:13 -0700 | [diff] [blame] | 406 | error = -1; |
| 407 | goto out_unlock; |
Davide Libenzi | 5071f97 | 2009-03-31 15:24:10 -0700 | [diff] [blame] | 408 | } |
| 409 | } |
| 410 | |
| 411 | /* Add the current task and cookie to the list */ |
Davide Libenzi | 3fe4a97 | 2009-06-17 16:25:58 -0700 | [diff] [blame] | 412 | tnode.ctx = ctx; |
Davide Libenzi | 5071f97 | 2009-03-31 15:24:10 -0700 | [diff] [blame] | 413 | tnode.cookie = cookie; |
| 414 | list_add(&tnode.llink, lsthead); |
| 415 | |
| 416 | spin_unlock_irqrestore(&ncalls->lock, flags); |
| 417 | |
| 418 | /* Call the nested function */ |
| 419 | error = (*nproc)(priv, cookie, call_nests); |
| 420 | |
| 421 | /* Remove the current task from the list */ |
| 422 | spin_lock_irqsave(&ncalls->lock, flags); |
| 423 | list_del(&tnode.llink); |
Davide Libenzi | 3fe4a97 | 2009-06-17 16:25:58 -0700 | [diff] [blame] | 424 | out_unlock: |
Davide Libenzi | 5071f97 | 2009-03-31 15:24:10 -0700 | [diff] [blame] | 425 | spin_unlock_irqrestore(&ncalls->lock, flags); |
| 426 | |
| 427 | return error; |
| 428 | } |
| 429 | |
Davide Libenzi | 2dfa4ee | 2009-03-31 15:24:22 -0700 | [diff] [blame] | 430 | #ifdef CONFIG_DEBUG_LOCK_ALLOC |
| 431 | static inline void ep_wake_up_nested(wait_queue_head_t *wqueue, |
| 432 | unsigned long events, int subclass) |
| 433 | { |
| 434 | unsigned long flags; |
| 435 | |
| 436 | spin_lock_irqsave_nested(&wqueue->lock, flags, subclass); |
| 437 | wake_up_locked_poll(wqueue, events); |
| 438 | spin_unlock_irqrestore(&wqueue->lock, flags); |
| 439 | } |
| 440 | #else |
| 441 | static inline void ep_wake_up_nested(wait_queue_head_t *wqueue, |
| 442 | unsigned long events, int subclass) |
| 443 | { |
| 444 | wake_up_poll(wqueue, events); |
| 445 | } |
| 446 | #endif |
| 447 | |
Davide Libenzi | 5071f97 | 2009-03-31 15:24:10 -0700 | [diff] [blame] | 448 | static int ep_poll_wakeup_proc(void *priv, void *cookie, int call_nests) |
| 449 | { |
Davide Libenzi | 2dfa4ee | 2009-03-31 15:24:22 -0700 | [diff] [blame] | 450 | ep_wake_up_nested((wait_queue_head_t *) cookie, POLLIN, |
| 451 | 1 + call_nests); |
Davide Libenzi | 5071f97 | 2009-03-31 15:24:10 -0700 | [diff] [blame] | 452 | return 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 453 | } |
| 454 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 455 | /* |
| 456 | * Perform a safe wake up of the poll wait list. The problem is that |
| 457 | * with the new callback'd wake up system, it is possible that the |
| 458 | * poll callback is reentered from inside the call to wake_up() done |
| 459 | * on the poll wait queue head. The rule is that we cannot reenter the |
Davide Libenzi | 5071f97 | 2009-03-31 15:24:10 -0700 | [diff] [blame] | 460 | * wake up code from the same task more than EP_MAX_NESTS times, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 461 | * and we cannot reenter the same wait queue head at all. This will |
| 462 | * enable to have a hierarchy of epoll file descriptor of no more than |
Davide Libenzi | 5071f97 | 2009-03-31 15:24:10 -0700 | [diff] [blame] | 463 | * EP_MAX_NESTS deep. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 464 | */ |
Davide Libenzi | 5071f97 | 2009-03-31 15:24:10 -0700 | [diff] [blame] | 465 | static void ep_poll_safewake(wait_queue_head_t *wq) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 466 | { |
Davide Libenzi | 3fe4a97 | 2009-06-17 16:25:58 -0700 | [diff] [blame] | 467 | int this_cpu = get_cpu(); |
| 468 | |
Davide Libenzi | 5071f97 | 2009-03-31 15:24:10 -0700 | [diff] [blame] | 469 | ep_call_nested(&poll_safewake_ncalls, EP_MAX_NESTS, |
Davide Libenzi | 3fe4a97 | 2009-06-17 16:25:58 -0700 | [diff] [blame] | 470 | ep_poll_wakeup_proc, NULL, wq, (void *) (long) this_cpu); |
| 471 | |
| 472 | put_cpu(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 473 | } |
| 474 | |
Oleg Nesterov | 971316f | 2012-02-24 20:07:29 +0100 | [diff] [blame] | 475 | static void ep_remove_wait_queue(struct eppoll_entry *pwq) |
| 476 | { |
| 477 | wait_queue_head_t *whead; |
| 478 | |
| 479 | rcu_read_lock(); |
| 480 | /* If it is cleared by POLLFREE, it should be rcu-safe */ |
| 481 | whead = rcu_dereference(pwq->whead); |
| 482 | if (whead) |
| 483 | remove_wait_queue(whead, &pwq->wait); |
| 484 | rcu_read_unlock(); |
| 485 | } |
| 486 | |
Davide Libenzi | 7699acd | 2007-05-10 22:23:23 -0700 | [diff] [blame] | 487 | /* |
Tony Battersby | d1bc90d | 2009-03-31 15:24:15 -0700 | [diff] [blame] | 488 | * This function unregisters poll callbacks from the associated file |
| 489 | * descriptor. Must be called with "mtx" held (or "epmutex" if called from |
| 490 | * ep_free). |
Davide Libenzi | 7699acd | 2007-05-10 22:23:23 -0700 | [diff] [blame] | 491 | */ |
| 492 | static void ep_unregister_pollwait(struct eventpoll *ep, struct epitem *epi) |
| 493 | { |
Davide Libenzi | 7699acd | 2007-05-10 22:23:23 -0700 | [diff] [blame] | 494 | struct list_head *lsthead = &epi->pwqlist; |
| 495 | struct eppoll_entry *pwq; |
| 496 | |
Tony Battersby | d1bc90d | 2009-03-31 15:24:15 -0700 | [diff] [blame] | 497 | while (!list_empty(lsthead)) { |
| 498 | pwq = list_first_entry(lsthead, struct eppoll_entry, llink); |
Davide Libenzi | 7699acd | 2007-05-10 22:23:23 -0700 | [diff] [blame] | 499 | |
Tony Battersby | d1bc90d | 2009-03-31 15:24:15 -0700 | [diff] [blame] | 500 | list_del(&pwq->llink); |
Oleg Nesterov | 971316f | 2012-02-24 20:07:29 +0100 | [diff] [blame] | 501 | ep_remove_wait_queue(pwq); |
Tony Battersby | d1bc90d | 2009-03-31 15:24:15 -0700 | [diff] [blame] | 502 | kmem_cache_free(pwq_cache, pwq); |
Davide Libenzi | 7699acd | 2007-05-10 22:23:23 -0700 | [diff] [blame] | 503 | } |
| 504 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 505 | |
Davide Libenzi | 5071f97 | 2009-03-31 15:24:10 -0700 | [diff] [blame] | 506 | /** |
| 507 | * ep_scan_ready_list - Scans the ready list in a way that makes possible for |
| 508 | * the scan code, to call f_op->poll(). Also allows for |
| 509 | * O(NumReady) performance. |
| 510 | * |
| 511 | * @ep: Pointer to the epoll private data structure. |
| 512 | * @sproc: Pointer to the scan callback. |
| 513 | * @priv: Private opaque data passed to the @sproc callback. |
Nelson Elhage | d8805e6 | 2011-10-31 17:13:14 -0700 | [diff] [blame] | 514 | * @depth: The current depth of recursive f_op->poll calls. |
Davide Libenzi | 5071f97 | 2009-03-31 15:24:10 -0700 | [diff] [blame] | 515 | * |
| 516 | * Returns: The same integer error code returned by the @sproc callback. |
| 517 | */ |
| 518 | static int ep_scan_ready_list(struct eventpoll *ep, |
| 519 | int (*sproc)(struct eventpoll *, |
| 520 | struct list_head *, void *), |
Nelson Elhage | d8805e6 | 2011-10-31 17:13:14 -0700 | [diff] [blame] | 521 | void *priv, |
| 522 | int depth) |
Davide Libenzi | 5071f97 | 2009-03-31 15:24:10 -0700 | [diff] [blame] | 523 | { |
| 524 | int error, pwake = 0; |
| 525 | unsigned long flags; |
| 526 | struct epitem *epi, *nepi; |
Davide Libenzi | 296e236 | 2009-03-31 15:24:11 -0700 | [diff] [blame] | 527 | LIST_HEAD(txlist); |
Davide Libenzi | 5071f97 | 2009-03-31 15:24:10 -0700 | [diff] [blame] | 528 | |
| 529 | /* |
| 530 | * We need to lock this because we could be hit by |
Tony Battersby | e057e15 | 2009-03-31 15:24:15 -0700 | [diff] [blame] | 531 | * eventpoll_release_file() and epoll_ctl(). |
Davide Libenzi | 5071f97 | 2009-03-31 15:24:10 -0700 | [diff] [blame] | 532 | */ |
Nelson Elhage | d8805e6 | 2011-10-31 17:13:14 -0700 | [diff] [blame] | 533 | mutex_lock_nested(&ep->mtx, depth); |
Davide Libenzi | 5071f97 | 2009-03-31 15:24:10 -0700 | [diff] [blame] | 534 | |
| 535 | /* |
| 536 | * Steal the ready list, and re-init the original one to the |
| 537 | * empty list. Also, set ep->ovflist to NULL so that events |
| 538 | * happening while looping w/out locks, are not lost. We cannot |
| 539 | * have the poll callback to queue directly on ep->rdllist, |
| 540 | * because we want the "sproc" callback to be able to do it |
| 541 | * in a lockless way. |
| 542 | */ |
| 543 | spin_lock_irqsave(&ep->lock, flags); |
Davide Libenzi | 296e236 | 2009-03-31 15:24:11 -0700 | [diff] [blame] | 544 | list_splice_init(&ep->rdllist, &txlist); |
Davide Libenzi | 5071f97 | 2009-03-31 15:24:10 -0700 | [diff] [blame] | 545 | ep->ovflist = NULL; |
| 546 | spin_unlock_irqrestore(&ep->lock, flags); |
| 547 | |
| 548 | /* |
| 549 | * Now call the callback function. |
| 550 | */ |
| 551 | error = (*sproc)(ep, &txlist, priv); |
| 552 | |
| 553 | spin_lock_irqsave(&ep->lock, flags); |
| 554 | /* |
| 555 | * During the time we spent inside the "sproc" callback, some |
| 556 | * other events might have been queued by the poll callback. |
| 557 | * We re-insert them inside the main ready-list here. |
| 558 | */ |
| 559 | for (nepi = ep->ovflist; (epi = nepi) != NULL; |
| 560 | nepi = epi->next, epi->next = EP_UNACTIVE_PTR) { |
| 561 | /* |
| 562 | * We need to check if the item is already in the list. |
| 563 | * During the "sproc" callback execution time, items are |
| 564 | * queued into ->ovflist but the "txlist" might already |
| 565 | * contain them, and the list_splice() below takes care of them. |
| 566 | */ |
| 567 | if (!ep_is_linked(&epi->rdllink)) |
| 568 | list_add_tail(&epi->rdllink, &ep->rdllist); |
| 569 | } |
| 570 | /* |
| 571 | * We need to set back ep->ovflist to EP_UNACTIVE_PTR, so that after |
| 572 | * releasing the lock, events will be queued in the normal way inside |
| 573 | * ep->rdllist. |
| 574 | */ |
| 575 | ep->ovflist = EP_UNACTIVE_PTR; |
| 576 | |
| 577 | /* |
| 578 | * Quickly re-inject items left on "txlist". |
| 579 | */ |
| 580 | list_splice(&txlist, &ep->rdllist); |
| 581 | |
| 582 | if (!list_empty(&ep->rdllist)) { |
| 583 | /* |
Davide Libenzi | 296e236 | 2009-03-31 15:24:11 -0700 | [diff] [blame] | 584 | * Wake up (if active) both the eventpoll wait list and |
| 585 | * the ->poll() wait list (delayed after we release the lock). |
Davide Libenzi | 5071f97 | 2009-03-31 15:24:10 -0700 | [diff] [blame] | 586 | */ |
| 587 | if (waitqueue_active(&ep->wq)) |
| 588 | wake_up_locked(&ep->wq); |
| 589 | if (waitqueue_active(&ep->poll_wait)) |
| 590 | pwake++; |
| 591 | } |
| 592 | spin_unlock_irqrestore(&ep->lock, flags); |
| 593 | |
| 594 | mutex_unlock(&ep->mtx); |
| 595 | |
| 596 | /* We have to call this outside the lock */ |
| 597 | if (pwake) |
| 598 | ep_poll_safewake(&ep->poll_wait); |
| 599 | |
| 600 | return error; |
| 601 | } |
| 602 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 603 | /* |
Davide Libenzi | 7699acd | 2007-05-10 22:23:23 -0700 | [diff] [blame] | 604 | * Removes a "struct epitem" from the eventpoll RB tree and deallocates |
Davide Libenzi | c7ea763 | 2007-05-15 01:40:47 -0700 | [diff] [blame] | 605 | * all the associated resources. Must be called with "mtx" held. |
Davide Libenzi | 7699acd | 2007-05-10 22:23:23 -0700 | [diff] [blame] | 606 | */ |
| 607 | static int ep_remove(struct eventpoll *ep, struct epitem *epi) |
| 608 | { |
Davide Libenzi | 7699acd | 2007-05-10 22:23:23 -0700 | [diff] [blame] | 609 | unsigned long flags; |
| 610 | struct file *file = epi->ffd.file; |
| 611 | |
| 612 | /* |
| 613 | * Removes poll wait queue hooks. We _have_ to do this without holding |
| 614 | * the "ep->lock" otherwise a deadlock might occur. This because of the |
| 615 | * sequence of the lock acquisition. Here we do "ep->lock" then the wait |
| 616 | * queue head lock when unregistering the wait queue. The wakeup callback |
| 617 | * will run by holding the wait queue head lock and will call our callback |
| 618 | * that will try to get "ep->lock". |
| 619 | */ |
| 620 | ep_unregister_pollwait(ep, epi); |
| 621 | |
| 622 | /* Remove the current item from the list of epoll hooks */ |
Jonathan Corbet | 6849991 | 2009-02-06 13:52:43 -0700 | [diff] [blame] | 623 | spin_lock(&file->f_lock); |
Davide Libenzi | 7699acd | 2007-05-10 22:23:23 -0700 | [diff] [blame] | 624 | if (ep_is_linked(&epi->fllink)) |
Davide Libenzi | 6192bd5 | 2007-05-08 00:25:41 -0700 | [diff] [blame] | 625 | list_del_init(&epi->fllink); |
Jonathan Corbet | 6849991 | 2009-02-06 13:52:43 -0700 | [diff] [blame] | 626 | spin_unlock(&file->f_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 627 | |
Davide Libenzi | cdac75e | 2008-04-29 00:58:34 -0700 | [diff] [blame] | 628 | rb_erase(&epi->rbn, &ep->rbr); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 629 | |
Davide Libenzi | c7ea763 | 2007-05-15 01:40:47 -0700 | [diff] [blame] | 630 | spin_lock_irqsave(&ep->lock, flags); |
| 631 | if (ep_is_linked(&epi->rdllink)) |
| 632 | list_del_init(&epi->rdllink); |
| 633 | spin_unlock_irqrestore(&ep->lock, flags); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 634 | |
Davide Libenzi | 7699acd | 2007-05-10 22:23:23 -0700 | [diff] [blame] | 635 | /* At this point it is safe to free the eventpoll item */ |
Davide Libenzi | c7ea763 | 2007-05-15 01:40:47 -0700 | [diff] [blame] | 636 | kmem_cache_free(epi_cache, epi); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 637 | |
Robin Holt | 52bd19f7 | 2011-01-12 17:00:01 -0800 | [diff] [blame] | 638 | atomic_long_dec(&ep->user->epoll_watches); |
Davide Libenzi | 7ef9964 | 2008-12-01 13:13:55 -0800 | [diff] [blame] | 639 | |
Davide Libenzi | c7ea763 | 2007-05-15 01:40:47 -0700 | [diff] [blame] | 640 | return 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 641 | } |
| 642 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 643 | static void ep_free(struct eventpoll *ep) |
| 644 | { |
| 645 | struct rb_node *rbp; |
| 646 | struct epitem *epi; |
| 647 | |
| 648 | /* We need to release all tasks waiting for these file */ |
| 649 | if (waitqueue_active(&ep->poll_wait)) |
Davide Libenzi | 5071f97 | 2009-03-31 15:24:10 -0700 | [diff] [blame] | 650 | ep_poll_safewake(&ep->poll_wait); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 651 | |
| 652 | /* |
| 653 | * We need to lock this because we could be hit by |
| 654 | * eventpoll_release_file() while we're freeing the "struct eventpoll". |
Davide Libenzi | d47de16 | 2007-05-15 01:40:41 -0700 | [diff] [blame] | 655 | * We do not need to hold "ep->mtx" here because the epoll file |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 656 | * is on the way to be removed and no one has references to it |
| 657 | * anymore. The only hit might come from eventpoll_release_file() but |
Lucas De Marchi | 25985ed | 2011-03-30 22:57:33 -0300 | [diff] [blame] | 658 | * holding "epmutex" is sufficient here. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 659 | */ |
Arjan van de Ven | 144efe3 | 2006-03-23 03:00:32 -0800 | [diff] [blame] | 660 | mutex_lock(&epmutex); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 661 | |
| 662 | /* |
| 663 | * Walks through the whole tree by unregistering poll callbacks. |
| 664 | */ |
| 665 | for (rbp = rb_first(&ep->rbr); rbp; rbp = rb_next(rbp)) { |
| 666 | epi = rb_entry(rbp, struct epitem, rbn); |
| 667 | |
| 668 | ep_unregister_pollwait(ep, epi); |
| 669 | } |
| 670 | |
| 671 | /* |
Davide Libenzi | 6192bd5 | 2007-05-08 00:25:41 -0700 | [diff] [blame] | 672 | * Walks through the whole tree by freeing each "struct epitem". At this |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 673 | * point we are sure no poll callbacks will be lingering around, and also by |
Davide Libenzi | d47de16 | 2007-05-15 01:40:41 -0700 | [diff] [blame] | 674 | * holding "epmutex" we can be sure that no file cleanup code will hit |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 675 | * us during this operation. So we can avoid the lock on "ep->lock". |
| 676 | */ |
Stephen Hemminger | c80544d | 2007-10-18 03:07:05 -0700 | [diff] [blame] | 677 | while ((rbp = rb_first(&ep->rbr)) != NULL) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 678 | epi = rb_entry(rbp, struct epitem, rbn); |
| 679 | ep_remove(ep, epi); |
| 680 | } |
| 681 | |
Arjan van de Ven | 144efe3 | 2006-03-23 03:00:32 -0800 | [diff] [blame] | 682 | mutex_unlock(&epmutex); |
Davide Libenzi | d47de16 | 2007-05-15 01:40:41 -0700 | [diff] [blame] | 683 | mutex_destroy(&ep->mtx); |
Davide Libenzi | 7ef9964 | 2008-12-01 13:13:55 -0800 | [diff] [blame] | 684 | free_uid(ep->user); |
Davide Libenzi | f0ee9aa | 2007-05-15 01:40:57 -0700 | [diff] [blame] | 685 | kfree(ep); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 686 | } |
| 687 | |
Davide Libenzi | 7699acd | 2007-05-10 22:23:23 -0700 | [diff] [blame] | 688 | static int ep_eventpoll_release(struct inode *inode, struct file *file) |
| 689 | { |
| 690 | struct eventpoll *ep = file->private_data; |
| 691 | |
Davide Libenzi | f0ee9aa | 2007-05-15 01:40:57 -0700 | [diff] [blame] | 692 | if (ep) |
Davide Libenzi | 7699acd | 2007-05-10 22:23:23 -0700 | [diff] [blame] | 693 | ep_free(ep); |
Davide Libenzi | 7699acd | 2007-05-10 22:23:23 -0700 | [diff] [blame] | 694 | |
Davide Libenzi | 7699acd | 2007-05-10 22:23:23 -0700 | [diff] [blame] | 695 | return 0; |
| 696 | } |
| 697 | |
Davide Libenzi | 296e236 | 2009-03-31 15:24:11 -0700 | [diff] [blame] | 698 | static int ep_read_events_proc(struct eventpoll *ep, struct list_head *head, |
| 699 | void *priv) |
Davide Libenzi | 5071f97 | 2009-03-31 15:24:10 -0700 | [diff] [blame] | 700 | { |
| 701 | struct epitem *epi, *tmp; |
| 702 | |
| 703 | list_for_each_entry_safe(epi, tmp, head, rdllink) { |
| 704 | if (epi->ffd.file->f_op->poll(epi->ffd.file, NULL) & |
| 705 | epi->event.events) |
| 706 | return POLLIN | POLLRDNORM; |
Davide Libenzi | 296e236 | 2009-03-31 15:24:11 -0700 | [diff] [blame] | 707 | else { |
Davide Libenzi | 5071f97 | 2009-03-31 15:24:10 -0700 | [diff] [blame] | 708 | /* |
| 709 | * Item has been dropped into the ready list by the poll |
| 710 | * callback, but it's not actually ready, as far as |
| 711 | * caller requested events goes. We can remove it here. |
| 712 | */ |
| 713 | list_del_init(&epi->rdllink); |
Davide Libenzi | 296e236 | 2009-03-31 15:24:11 -0700 | [diff] [blame] | 714 | } |
Davide Libenzi | 5071f97 | 2009-03-31 15:24:10 -0700 | [diff] [blame] | 715 | } |
| 716 | |
| 717 | return 0; |
| 718 | } |
| 719 | |
| 720 | static int ep_poll_readyevents_proc(void *priv, void *cookie, int call_nests) |
| 721 | { |
Nelson Elhage | d8805e6 | 2011-10-31 17:13:14 -0700 | [diff] [blame] | 722 | return ep_scan_ready_list(priv, ep_read_events_proc, NULL, call_nests + 1); |
Davide Libenzi | 5071f97 | 2009-03-31 15:24:10 -0700 | [diff] [blame] | 723 | } |
| 724 | |
Davide Libenzi | 7699acd | 2007-05-10 22:23:23 -0700 | [diff] [blame] | 725 | static unsigned int ep_eventpoll_poll(struct file *file, poll_table *wait) |
| 726 | { |
Davide Libenzi | 5071f97 | 2009-03-31 15:24:10 -0700 | [diff] [blame] | 727 | int pollflags; |
Davide Libenzi | 7699acd | 2007-05-10 22:23:23 -0700 | [diff] [blame] | 728 | struct eventpoll *ep = file->private_data; |
| 729 | |
| 730 | /* Insert inside our poll wait queue */ |
| 731 | poll_wait(file, &ep->poll_wait, wait); |
| 732 | |
Davide Libenzi | 5071f97 | 2009-03-31 15:24:10 -0700 | [diff] [blame] | 733 | /* |
| 734 | * Proceed to find out if wanted events are really available inside |
| 735 | * the ready list. This need to be done under ep_call_nested() |
| 736 | * supervision, since the call to f_op->poll() done on listed files |
| 737 | * could re-enter here. |
| 738 | */ |
| 739 | pollflags = ep_call_nested(&poll_readywalk_ncalls, EP_MAX_NESTS, |
Davide Libenzi | 3fe4a97 | 2009-06-17 16:25:58 -0700 | [diff] [blame] | 740 | ep_poll_readyevents_proc, ep, ep, current); |
Davide Libenzi | 7699acd | 2007-05-10 22:23:23 -0700 | [diff] [blame] | 741 | |
Davide Libenzi | 296e236 | 2009-03-31 15:24:11 -0700 | [diff] [blame] | 742 | return pollflags != -1 ? pollflags : 0; |
Davide Libenzi | 7699acd | 2007-05-10 22:23:23 -0700 | [diff] [blame] | 743 | } |
| 744 | |
| 745 | /* File callbacks that implement the eventpoll file behaviour */ |
| 746 | static const struct file_operations eventpoll_fops = { |
| 747 | .release = ep_eventpoll_release, |
Arnd Bergmann | 6038f37 | 2010-08-15 18:52:59 +0200 | [diff] [blame] | 748 | .poll = ep_eventpoll_poll, |
| 749 | .llseek = noop_llseek, |
Davide Libenzi | 7699acd | 2007-05-10 22:23:23 -0700 | [diff] [blame] | 750 | }; |
| 751 | |
Davide Libenzi | 7699acd | 2007-05-10 22:23:23 -0700 | [diff] [blame] | 752 | /* |
| 753 | * This is called from eventpoll_release() to unlink files from the eventpoll |
| 754 | * interface. We need to have this facility to cleanup correctly files that are |
| 755 | * closed without being removed from the eventpoll interface. |
| 756 | */ |
| 757 | void eventpoll_release_file(struct file *file) |
| 758 | { |
| 759 | struct list_head *lsthead = &file->f_ep_links; |
| 760 | struct eventpoll *ep; |
| 761 | struct epitem *epi; |
| 762 | |
| 763 | /* |
Jonathan Corbet | 6849991 | 2009-02-06 13:52:43 -0700 | [diff] [blame] | 764 | * We don't want to get "file->f_lock" because it is not |
Davide Libenzi | 7699acd | 2007-05-10 22:23:23 -0700 | [diff] [blame] | 765 | * necessary. It is not necessary because we're in the "struct file" |
Lucas De Marchi | 25985ed | 2011-03-30 22:57:33 -0300 | [diff] [blame] | 766 | * cleanup path, and this means that no one is using this file anymore. |
Davide Libenzi | 5071f97 | 2009-03-31 15:24:10 -0700 | [diff] [blame] | 767 | * So, for example, epoll_ctl() cannot hit here since if we reach this |
Davide Libenzi | 67647d0 | 2007-05-15 01:40:52 -0700 | [diff] [blame] | 768 | * point, the file counter already went to zero and fget() would fail. |
Davide Libenzi | d47de16 | 2007-05-15 01:40:41 -0700 | [diff] [blame] | 769 | * The only hit might come from ep_free() but by holding the mutex |
Davide Libenzi | 7699acd | 2007-05-10 22:23:23 -0700 | [diff] [blame] | 770 | * will correctly serialize the operation. We do need to acquire |
Davide Libenzi | d47de16 | 2007-05-15 01:40:41 -0700 | [diff] [blame] | 771 | * "ep->mtx" after "epmutex" because ep_remove() requires it when called |
Davide Libenzi | 7699acd | 2007-05-10 22:23:23 -0700 | [diff] [blame] | 772 | * from anywhere but ep_free(). |
Jonathan Corbet | 6849991 | 2009-02-06 13:52:43 -0700 | [diff] [blame] | 773 | * |
| 774 | * Besides, ep_remove() acquires the lock, so we can't hold it here. |
Davide Libenzi | 7699acd | 2007-05-10 22:23:23 -0700 | [diff] [blame] | 775 | */ |
| 776 | mutex_lock(&epmutex); |
| 777 | |
| 778 | while (!list_empty(lsthead)) { |
| 779 | epi = list_first_entry(lsthead, struct epitem, fllink); |
| 780 | |
| 781 | ep = epi->ep; |
| 782 | list_del_init(&epi->fllink); |
Nelson Elhage | d8805e6 | 2011-10-31 17:13:14 -0700 | [diff] [blame] | 783 | mutex_lock_nested(&ep->mtx, 0); |
Davide Libenzi | 7699acd | 2007-05-10 22:23:23 -0700 | [diff] [blame] | 784 | ep_remove(ep, epi); |
Davide Libenzi | d47de16 | 2007-05-15 01:40:41 -0700 | [diff] [blame] | 785 | mutex_unlock(&ep->mtx); |
Davide Libenzi | 7699acd | 2007-05-10 22:23:23 -0700 | [diff] [blame] | 786 | } |
| 787 | |
| 788 | mutex_unlock(&epmutex); |
| 789 | } |
| 790 | |
| 791 | static int ep_alloc(struct eventpoll **pep) |
| 792 | { |
Davide Libenzi | 7ef9964 | 2008-12-01 13:13:55 -0800 | [diff] [blame] | 793 | int error; |
| 794 | struct user_struct *user; |
| 795 | struct eventpoll *ep; |
Davide Libenzi | 7699acd | 2007-05-10 22:23:23 -0700 | [diff] [blame] | 796 | |
Davide Libenzi | 7ef9964 | 2008-12-01 13:13:55 -0800 | [diff] [blame] | 797 | user = get_current_user(); |
Davide Libenzi | 7ef9964 | 2008-12-01 13:13:55 -0800 | [diff] [blame] | 798 | error = -ENOMEM; |
| 799 | ep = kzalloc(sizeof(*ep), GFP_KERNEL); |
| 800 | if (unlikely(!ep)) |
| 801 | goto free_uid; |
Davide Libenzi | 7699acd | 2007-05-10 22:23:23 -0700 | [diff] [blame] | 802 | |
Davide Libenzi | c7ea763 | 2007-05-15 01:40:47 -0700 | [diff] [blame] | 803 | spin_lock_init(&ep->lock); |
Davide Libenzi | d47de16 | 2007-05-15 01:40:41 -0700 | [diff] [blame] | 804 | mutex_init(&ep->mtx); |
Davide Libenzi | 7699acd | 2007-05-10 22:23:23 -0700 | [diff] [blame] | 805 | init_waitqueue_head(&ep->wq); |
| 806 | init_waitqueue_head(&ep->poll_wait); |
| 807 | INIT_LIST_HEAD(&ep->rdllist); |
| 808 | ep->rbr = RB_ROOT; |
Davide Libenzi | d47de16 | 2007-05-15 01:40:41 -0700 | [diff] [blame] | 809 | ep->ovflist = EP_UNACTIVE_PTR; |
Davide Libenzi | 7ef9964 | 2008-12-01 13:13:55 -0800 | [diff] [blame] | 810 | ep->user = user; |
Davide Libenzi | 7699acd | 2007-05-10 22:23:23 -0700 | [diff] [blame] | 811 | |
| 812 | *pep = ep; |
| 813 | |
Davide Libenzi | 7699acd | 2007-05-10 22:23:23 -0700 | [diff] [blame] | 814 | return 0; |
Davide Libenzi | 7ef9964 | 2008-12-01 13:13:55 -0800 | [diff] [blame] | 815 | |
| 816 | free_uid: |
| 817 | free_uid(user); |
| 818 | return error; |
Davide Libenzi | 7699acd | 2007-05-10 22:23:23 -0700 | [diff] [blame] | 819 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 820 | |
| 821 | /* |
Davide Libenzi | c7ea763 | 2007-05-15 01:40:47 -0700 | [diff] [blame] | 822 | * Search the file inside the eventpoll tree. The RB tree operations |
| 823 | * are protected by the "mtx" mutex, and ep_find() must be called with |
| 824 | * "mtx" held. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 825 | */ |
| 826 | static struct epitem *ep_find(struct eventpoll *ep, struct file *file, int fd) |
| 827 | { |
| 828 | int kcmp; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 829 | struct rb_node *rbp; |
| 830 | struct epitem *epi, *epir = NULL; |
| 831 | struct epoll_filefd ffd; |
| 832 | |
Pekka Enberg | b030a4d | 2005-06-23 00:10:03 -0700 | [diff] [blame] | 833 | ep_set_ffd(&ffd, file, fd); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 834 | for (rbp = ep->rbr.rb_node; rbp; ) { |
| 835 | epi = rb_entry(rbp, struct epitem, rbn); |
Pekka Enberg | b030a4d | 2005-06-23 00:10:03 -0700 | [diff] [blame] | 836 | kcmp = ep_cmp_ffd(&ffd, &epi->ffd); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 837 | if (kcmp > 0) |
| 838 | rbp = rbp->rb_right; |
| 839 | else if (kcmp < 0) |
| 840 | rbp = rbp->rb_left; |
| 841 | else { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 842 | epir = epi; |
| 843 | break; |
| 844 | } |
| 845 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 846 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 847 | return epir; |
| 848 | } |
| 849 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 850 | /* |
Davide Libenzi | 7699acd | 2007-05-10 22:23:23 -0700 | [diff] [blame] | 851 | * This is the callback that is passed to the wait queue wakeup |
Daniel Baluta | bf6a41d | 2011-01-30 23:42:29 +0200 | [diff] [blame] | 852 | * mechanism. It is called by the stored file descriptors when they |
Davide Libenzi | 7699acd | 2007-05-10 22:23:23 -0700 | [diff] [blame] | 853 | * have events to report. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 854 | */ |
Davide Libenzi | 7699acd | 2007-05-10 22:23:23 -0700 | [diff] [blame] | 855 | static int ep_poll_callback(wait_queue_t *wait, unsigned mode, int sync, void *key) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 856 | { |
Davide Libenzi | 7699acd | 2007-05-10 22:23:23 -0700 | [diff] [blame] | 857 | int pwake = 0; |
| 858 | unsigned long flags; |
| 859 | struct epitem *epi = ep_item_from_wait(wait); |
| 860 | struct eventpoll *ep = epi->ep; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 861 | |
Oleg Nesterov | 971316f | 2012-02-24 20:07:29 +0100 | [diff] [blame] | 862 | if ((unsigned long)key & POLLFREE) { |
| 863 | ep_pwq_from_wait(wait)->whead = NULL; |
| 864 | /* |
| 865 | * whead = NULL above can race with ep_remove_wait_queue() |
| 866 | * which can do another remove_wait_queue() after us, so we |
| 867 | * can't use __remove_wait_queue(). whead->lock is held by |
| 868 | * the caller. |
| 869 | */ |
Oleg Nesterov | d80e731 | 2012-02-24 20:07:11 +0100 | [diff] [blame] | 870 | list_del_init(&wait->task_list); |
Oleg Nesterov | 971316f | 2012-02-24 20:07:29 +0100 | [diff] [blame] | 871 | } |
Oleg Nesterov | d80e731 | 2012-02-24 20:07:11 +0100 | [diff] [blame] | 872 | |
Davide Libenzi | c7ea763 | 2007-05-15 01:40:47 -0700 | [diff] [blame] | 873 | spin_lock_irqsave(&ep->lock, flags); |
Davide Libenzi | 7699acd | 2007-05-10 22:23:23 -0700 | [diff] [blame] | 874 | |
| 875 | /* |
| 876 | * If the event mask does not contain any poll(2) event, we consider the |
| 877 | * descriptor to be disabled. This condition is likely the effect of the |
| 878 | * EPOLLONESHOT bit that disables the descriptor when an event is received, |
| 879 | * until the next EPOLL_CTL_MOD will be issued. |
| 880 | */ |
| 881 | if (!(epi->event.events & ~EP_PRIVATE_BITS)) |
Davide Libenzi | d47de16 | 2007-05-15 01:40:41 -0700 | [diff] [blame] | 882 | goto out_unlock; |
| 883 | |
| 884 | /* |
Davide Libenzi | 2dfa4ee | 2009-03-31 15:24:22 -0700 | [diff] [blame] | 885 | * Check the events coming with the callback. At this stage, not |
| 886 | * every device reports the events in the "key" parameter of the |
| 887 | * callback. We need to be able to handle both cases here, hence the |
| 888 | * test for "key" != NULL before the event match test. |
| 889 | */ |
| 890 | if (key && !((unsigned long) key & epi->event.events)) |
| 891 | goto out_unlock; |
| 892 | |
| 893 | /* |
Daniel Baluta | bf6a41d | 2011-01-30 23:42:29 +0200 | [diff] [blame] | 894 | * If we are transferring events to userspace, we can hold no locks |
Davide Libenzi | d47de16 | 2007-05-15 01:40:41 -0700 | [diff] [blame] | 895 | * (because we're accessing user memory, and because of linux f_op->poll() |
Daniel Baluta | bf6a41d | 2011-01-30 23:42:29 +0200 | [diff] [blame] | 896 | * semantics). All the events that happen during that period of time are |
Davide Libenzi | d47de16 | 2007-05-15 01:40:41 -0700 | [diff] [blame] | 897 | * chained in ep->ovflist and requeued later on. |
| 898 | */ |
| 899 | if (unlikely(ep->ovflist != EP_UNACTIVE_PTR)) { |
| 900 | if (epi->next == EP_UNACTIVE_PTR) { |
| 901 | epi->next = ep->ovflist; |
| 902 | ep->ovflist = epi; |
| 903 | } |
| 904 | goto out_unlock; |
| 905 | } |
Davide Libenzi | 7699acd | 2007-05-10 22:23:23 -0700 | [diff] [blame] | 906 | |
| 907 | /* If this file is already in the ready list we exit soon */ |
Davide Libenzi | 5071f97 | 2009-03-31 15:24:10 -0700 | [diff] [blame] | 908 | if (!ep_is_linked(&epi->rdllink)) |
| 909 | list_add_tail(&epi->rdllink, &ep->rdllist); |
Davide Libenzi | 7699acd | 2007-05-10 22:23:23 -0700 | [diff] [blame] | 910 | |
Davide Libenzi | 7699acd | 2007-05-10 22:23:23 -0700 | [diff] [blame] | 911 | /* |
| 912 | * Wake up ( if active ) both the eventpoll wait list and the ->poll() |
| 913 | * wait list. |
| 914 | */ |
| 915 | if (waitqueue_active(&ep->wq)) |
Matthew Wilcox | 4a6e9e2 | 2007-08-30 16:10:22 -0400 | [diff] [blame] | 916 | wake_up_locked(&ep->wq); |
Davide Libenzi | 7699acd | 2007-05-10 22:23:23 -0700 | [diff] [blame] | 917 | if (waitqueue_active(&ep->poll_wait)) |
| 918 | pwake++; |
| 919 | |
Davide Libenzi | d47de16 | 2007-05-15 01:40:41 -0700 | [diff] [blame] | 920 | out_unlock: |
Davide Libenzi | c7ea763 | 2007-05-15 01:40:47 -0700 | [diff] [blame] | 921 | spin_unlock_irqrestore(&ep->lock, flags); |
Davide Libenzi | 7699acd | 2007-05-10 22:23:23 -0700 | [diff] [blame] | 922 | |
| 923 | /* We have to call this outside the lock */ |
| 924 | if (pwake) |
Davide Libenzi | 5071f97 | 2009-03-31 15:24:10 -0700 | [diff] [blame] | 925 | ep_poll_safewake(&ep->poll_wait); |
Davide Libenzi | 7699acd | 2007-05-10 22:23:23 -0700 | [diff] [blame] | 926 | |
| 927 | return 1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 928 | } |
| 929 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 930 | /* |
| 931 | * This is the callback that is used to add our wait queue to the |
| 932 | * target file wakeup lists. |
| 933 | */ |
| 934 | static void ep_ptable_queue_proc(struct file *file, wait_queue_head_t *whead, |
| 935 | poll_table *pt) |
| 936 | { |
Pekka Enberg | b030a4d | 2005-06-23 00:10:03 -0700 | [diff] [blame] | 937 | struct epitem *epi = ep_item_from_epqueue(pt); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 938 | struct eppoll_entry *pwq; |
| 939 | |
Christoph Lameter | e94b176 | 2006-12-06 20:33:17 -0800 | [diff] [blame] | 940 | if (epi->nwait >= 0 && (pwq = kmem_cache_alloc(pwq_cache, GFP_KERNEL))) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 941 | init_waitqueue_func_entry(&pwq->wait, ep_poll_callback); |
| 942 | pwq->whead = whead; |
| 943 | pwq->base = epi; |
| 944 | add_wait_queue(whead, &pwq->wait); |
| 945 | list_add_tail(&pwq->llink, &epi->pwqlist); |
| 946 | epi->nwait++; |
Davide Libenzi | 296e236 | 2009-03-31 15:24:11 -0700 | [diff] [blame] | 947 | } else { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 948 | /* We have to signal that an error occurred */ |
| 949 | epi->nwait = -1; |
Davide Libenzi | 296e236 | 2009-03-31 15:24:11 -0700 | [diff] [blame] | 950 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 951 | } |
| 952 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 953 | static void ep_rbtree_insert(struct eventpoll *ep, struct epitem *epi) |
| 954 | { |
| 955 | int kcmp; |
| 956 | struct rb_node **p = &ep->rbr.rb_node, *parent = NULL; |
| 957 | struct epitem *epic; |
| 958 | |
| 959 | while (*p) { |
| 960 | parent = *p; |
| 961 | epic = rb_entry(parent, struct epitem, rbn); |
Pekka Enberg | b030a4d | 2005-06-23 00:10:03 -0700 | [diff] [blame] | 962 | kcmp = ep_cmp_ffd(&epi->ffd, &epic->ffd); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 963 | if (kcmp > 0) |
| 964 | p = &parent->rb_right; |
| 965 | else |
| 966 | p = &parent->rb_left; |
| 967 | } |
| 968 | rb_link_node(&epi->rbn, parent, p); |
| 969 | rb_insert_color(&epi->rbn, &ep->rbr); |
| 970 | } |
| 971 | |
Jason Baron | 28d82dc | 2012-01-12 17:17:43 -0800 | [diff] [blame] | 972 | |
| 973 | |
| 974 | #define PATH_ARR_SIZE 5 |
| 975 | /* |
| 976 | * These are the number paths of length 1 to 5, that we are allowing to emanate |
| 977 | * from a single file of interest. For example, we allow 1000 paths of length |
| 978 | * 1, to emanate from each file of interest. This essentially represents the |
| 979 | * potential wakeup paths, which need to be limited in order to avoid massive |
| 980 | * uncontrolled wakeup storms. The common use case should be a single ep which |
| 981 | * is connected to n file sources. In this case each file source has 1 path |
| 982 | * of length 1. Thus, the numbers below should be more than sufficient. These |
| 983 | * path limits are enforced during an EPOLL_CTL_ADD operation, since a modify |
| 984 | * and delete can't add additional paths. Protected by the epmutex. |
| 985 | */ |
| 986 | static const int path_limits[PATH_ARR_SIZE] = { 1000, 500, 100, 50, 10 }; |
| 987 | static int path_count[PATH_ARR_SIZE]; |
| 988 | |
| 989 | static int path_count_inc(int nests) |
| 990 | { |
| 991 | if (++path_count[nests] > path_limits[nests]) |
| 992 | return -1; |
| 993 | return 0; |
| 994 | } |
| 995 | |
| 996 | static void path_count_init(void) |
| 997 | { |
| 998 | int i; |
| 999 | |
| 1000 | for (i = 0; i < PATH_ARR_SIZE; i++) |
| 1001 | path_count[i] = 0; |
| 1002 | } |
| 1003 | |
| 1004 | static int reverse_path_check_proc(void *priv, void *cookie, int call_nests) |
| 1005 | { |
| 1006 | int error = 0; |
| 1007 | struct file *file = priv; |
| 1008 | struct file *child_file; |
| 1009 | struct epitem *epi; |
| 1010 | |
| 1011 | list_for_each_entry(epi, &file->f_ep_links, fllink) { |
| 1012 | child_file = epi->ep->file; |
| 1013 | if (is_file_epoll(child_file)) { |
| 1014 | if (list_empty(&child_file->f_ep_links)) { |
| 1015 | if (path_count_inc(call_nests)) { |
| 1016 | error = -1; |
| 1017 | break; |
| 1018 | } |
| 1019 | } else { |
| 1020 | error = ep_call_nested(&poll_loop_ncalls, |
| 1021 | EP_MAX_NESTS, |
| 1022 | reverse_path_check_proc, |
| 1023 | child_file, child_file, |
| 1024 | current); |
| 1025 | } |
| 1026 | if (error != 0) |
| 1027 | break; |
| 1028 | } else { |
| 1029 | printk(KERN_ERR "reverse_path_check_proc: " |
| 1030 | "file is not an ep!\n"); |
| 1031 | } |
| 1032 | } |
| 1033 | return error; |
| 1034 | } |
| 1035 | |
| 1036 | /** |
| 1037 | * reverse_path_check - The tfile_check_list is list of file *, which have |
| 1038 | * links that are proposed to be newly added. We need to |
| 1039 | * make sure that those added links don't add too many |
| 1040 | * paths such that we will spend all our time waking up |
| 1041 | * eventpoll objects. |
| 1042 | * |
| 1043 | * Returns: Returns zero if the proposed links don't create too many paths, |
| 1044 | * -1 otherwise. |
| 1045 | */ |
| 1046 | static int reverse_path_check(void) |
| 1047 | { |
| 1048 | int length = 0; |
| 1049 | int error = 0; |
| 1050 | struct file *current_file; |
| 1051 | |
| 1052 | /* let's call this for all tfiles */ |
| 1053 | list_for_each_entry(current_file, &tfile_check_list, f_tfile_llink) { |
| 1054 | length++; |
| 1055 | path_count_init(); |
| 1056 | error = ep_call_nested(&poll_loop_ncalls, EP_MAX_NESTS, |
| 1057 | reverse_path_check_proc, current_file, |
| 1058 | current_file, current); |
| 1059 | if (error) |
| 1060 | break; |
| 1061 | } |
| 1062 | return error; |
| 1063 | } |
| 1064 | |
Davide Libenzi | c7ea763 | 2007-05-15 01:40:47 -0700 | [diff] [blame] | 1065 | /* |
| 1066 | * Must be called with "mtx" held. |
| 1067 | */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1068 | static int ep_insert(struct eventpoll *ep, struct epoll_event *event, |
| 1069 | struct file *tfile, int fd) |
| 1070 | { |
| 1071 | int error, revents, pwake = 0; |
| 1072 | unsigned long flags; |
Robin Holt | 52bd19f7 | 2011-01-12 17:00:01 -0800 | [diff] [blame] | 1073 | long user_watches; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1074 | struct epitem *epi; |
| 1075 | struct ep_pqueue epq; |
| 1076 | |
Robin Holt | 52bd19f7 | 2011-01-12 17:00:01 -0800 | [diff] [blame] | 1077 | user_watches = atomic_long_read(&ep->user->epoll_watches); |
| 1078 | if (unlikely(user_watches >= max_user_watches)) |
Davide Libenzi | 7ef9964 | 2008-12-01 13:13:55 -0800 | [diff] [blame] | 1079 | return -ENOSPC; |
Christoph Lameter | e94b176 | 2006-12-06 20:33:17 -0800 | [diff] [blame] | 1080 | if (!(epi = kmem_cache_alloc(epi_cache, GFP_KERNEL))) |
Davide Libenzi | 7ef9964 | 2008-12-01 13:13:55 -0800 | [diff] [blame] | 1081 | return -ENOMEM; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1082 | |
| 1083 | /* Item initialization follow here ... */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1084 | INIT_LIST_HEAD(&epi->rdllink); |
| 1085 | INIT_LIST_HEAD(&epi->fllink); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1086 | INIT_LIST_HEAD(&epi->pwqlist); |
| 1087 | epi->ep = ep; |
Pekka Enberg | b030a4d | 2005-06-23 00:10:03 -0700 | [diff] [blame] | 1088 | ep_set_ffd(&epi->ffd, tfile, fd); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1089 | epi->event = *event; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1090 | epi->nwait = 0; |
Davide Libenzi | d47de16 | 2007-05-15 01:40:41 -0700 | [diff] [blame] | 1091 | epi->next = EP_UNACTIVE_PTR; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1092 | |
| 1093 | /* Initialize the poll table using the queue callback */ |
| 1094 | epq.epi = epi; |
| 1095 | init_poll_funcptr(&epq.pt, ep_ptable_queue_proc); |
| 1096 | |
| 1097 | /* |
| 1098 | * Attach the item to the poll hooks and get current event bits. |
| 1099 | * We can safely use the file* here because its usage count has |
Davide Libenzi | c7ea763 | 2007-05-15 01:40:47 -0700 | [diff] [blame] | 1100 | * been increased by the caller of this function. Note that after |
| 1101 | * this operation completes, the poll callback can start hitting |
| 1102 | * the new item. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1103 | */ |
| 1104 | revents = tfile->f_op->poll(tfile, &epq.pt); |
| 1105 | |
| 1106 | /* |
| 1107 | * We have to check if something went wrong during the poll wait queue |
| 1108 | * install process. Namely an allocation for a wait queue failed due |
| 1109 | * high memory pressure. |
| 1110 | */ |
Davide Libenzi | 7ef9964 | 2008-12-01 13:13:55 -0800 | [diff] [blame] | 1111 | error = -ENOMEM; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1112 | if (epi->nwait < 0) |
Davide Libenzi | 7699acd | 2007-05-10 22:23:23 -0700 | [diff] [blame] | 1113 | goto error_unregister; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1114 | |
| 1115 | /* Add the current item to the list of active epoll hook for this file */ |
Jonathan Corbet | 6849991 | 2009-02-06 13:52:43 -0700 | [diff] [blame] | 1116 | spin_lock(&tfile->f_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1117 | list_add_tail(&epi->fllink, &tfile->f_ep_links); |
Jonathan Corbet | 6849991 | 2009-02-06 13:52:43 -0700 | [diff] [blame] | 1118 | spin_unlock(&tfile->f_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1119 | |
Davide Libenzi | c7ea763 | 2007-05-15 01:40:47 -0700 | [diff] [blame] | 1120 | /* |
| 1121 | * Add the current item to the RB tree. All RB tree operations are |
| 1122 | * protected by "mtx", and ep_insert() is called with "mtx" held. |
| 1123 | */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1124 | ep_rbtree_insert(ep, epi); |
| 1125 | |
Jason Baron | 28d82dc | 2012-01-12 17:17:43 -0800 | [diff] [blame] | 1126 | /* now check if we've created too many backpaths */ |
| 1127 | error = -EINVAL; |
| 1128 | if (reverse_path_check()) |
| 1129 | goto error_remove_epi; |
| 1130 | |
Davide Libenzi | c7ea763 | 2007-05-15 01:40:47 -0700 | [diff] [blame] | 1131 | /* We have to drop the new item inside our item list to keep track of it */ |
| 1132 | spin_lock_irqsave(&ep->lock, flags); |
| 1133 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1134 | /* If the file is already "ready" we drop it inside the ready list */ |
Pekka Enberg | b030a4d | 2005-06-23 00:10:03 -0700 | [diff] [blame] | 1135 | if ((revents & event->events) && !ep_is_linked(&epi->rdllink)) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1136 | list_add_tail(&epi->rdllink, &ep->rdllist); |
| 1137 | |
| 1138 | /* Notify waiting tasks that events are available */ |
| 1139 | if (waitqueue_active(&ep->wq)) |
Matthew Wilcox | 4a6e9e2 | 2007-08-30 16:10:22 -0400 | [diff] [blame] | 1140 | wake_up_locked(&ep->wq); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1141 | if (waitqueue_active(&ep->poll_wait)) |
| 1142 | pwake++; |
| 1143 | } |
| 1144 | |
Davide Libenzi | c7ea763 | 2007-05-15 01:40:47 -0700 | [diff] [blame] | 1145 | spin_unlock_irqrestore(&ep->lock, flags); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1146 | |
Robin Holt | 52bd19f7 | 2011-01-12 17:00:01 -0800 | [diff] [blame] | 1147 | atomic_long_inc(&ep->user->epoll_watches); |
Davide Libenzi | 7ef9964 | 2008-12-01 13:13:55 -0800 | [diff] [blame] | 1148 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1149 | /* We have to call this outside the lock */ |
| 1150 | if (pwake) |
Davide Libenzi | 5071f97 | 2009-03-31 15:24:10 -0700 | [diff] [blame] | 1151 | ep_poll_safewake(&ep->poll_wait); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1152 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1153 | return 0; |
| 1154 | |
Jason Baron | 28d82dc | 2012-01-12 17:17:43 -0800 | [diff] [blame] | 1155 | error_remove_epi: |
| 1156 | spin_lock(&tfile->f_lock); |
| 1157 | if (ep_is_linked(&epi->fllink)) |
| 1158 | list_del_init(&epi->fllink); |
| 1159 | spin_unlock(&tfile->f_lock); |
| 1160 | |
| 1161 | rb_erase(&epi->rbn, &ep->rbr); |
| 1162 | |
Davide Libenzi | 7699acd | 2007-05-10 22:23:23 -0700 | [diff] [blame] | 1163 | error_unregister: |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1164 | ep_unregister_pollwait(ep, epi); |
| 1165 | |
| 1166 | /* |
| 1167 | * We need to do this because an event could have been arrived on some |
Davide Libenzi | 67647d0 | 2007-05-15 01:40:52 -0700 | [diff] [blame] | 1168 | * allocated wait queue. Note that we don't care about the ep->ovflist |
| 1169 | * list, since that is used/cleaned only inside a section bound by "mtx". |
| 1170 | * And ep_insert() is called with "mtx" held. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1171 | */ |
Davide Libenzi | c7ea763 | 2007-05-15 01:40:47 -0700 | [diff] [blame] | 1172 | spin_lock_irqsave(&ep->lock, flags); |
Pekka Enberg | b030a4d | 2005-06-23 00:10:03 -0700 | [diff] [blame] | 1173 | if (ep_is_linked(&epi->rdllink)) |
Davide Libenzi | 6192bd5 | 2007-05-08 00:25:41 -0700 | [diff] [blame] | 1174 | list_del_init(&epi->rdllink); |
Davide Libenzi | c7ea763 | 2007-05-15 01:40:47 -0700 | [diff] [blame] | 1175 | spin_unlock_irqrestore(&ep->lock, flags); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1176 | |
Pekka Enberg | b030a4d | 2005-06-23 00:10:03 -0700 | [diff] [blame] | 1177 | kmem_cache_free(epi_cache, epi); |
Davide Libenzi | 7ef9964 | 2008-12-01 13:13:55 -0800 | [diff] [blame] | 1178 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1179 | return error; |
| 1180 | } |
| 1181 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1182 | /* |
| 1183 | * Modify the interest event mask by dropping an event if the new mask |
Davide Libenzi | c7ea763 | 2007-05-15 01:40:47 -0700 | [diff] [blame] | 1184 | * has a match in the current file status. Must be called with "mtx" held. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1185 | */ |
| 1186 | static int ep_modify(struct eventpoll *ep, struct epitem *epi, struct epoll_event *event) |
| 1187 | { |
| 1188 | int pwake = 0; |
| 1189 | unsigned int revents; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1190 | |
| 1191 | /* |
Tony Battersby | e057e15 | 2009-03-31 15:24:15 -0700 | [diff] [blame] | 1192 | * Set the new event interest mask before calling f_op->poll(); |
| 1193 | * otherwise we might miss an event that happens between the |
| 1194 | * f_op->poll() call and the new event set registering. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1195 | */ |
| 1196 | epi->event.events = event->events; |
Tony Battersby | e057e15 | 2009-03-31 15:24:15 -0700 | [diff] [blame] | 1197 | epi->event.data = event->data; /* protected by mtx */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1198 | |
| 1199 | /* |
| 1200 | * Get current event bits. We can safely use the file* here because |
| 1201 | * its usage count has been increased by the caller of this function. |
| 1202 | */ |
| 1203 | revents = epi->ffd.file->f_op->poll(epi->ffd.file, NULL); |
| 1204 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1205 | /* |
Davide Libenzi | c7ea763 | 2007-05-15 01:40:47 -0700 | [diff] [blame] | 1206 | * If the item is "hot" and it is not registered inside the ready |
Davide Libenzi | 67647d0 | 2007-05-15 01:40:52 -0700 | [diff] [blame] | 1207 | * list, push it inside. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1208 | */ |
Davide Libenzi | c7ea763 | 2007-05-15 01:40:47 -0700 | [diff] [blame] | 1209 | if (revents & event->events) { |
Tony Battersby | e057e15 | 2009-03-31 15:24:15 -0700 | [diff] [blame] | 1210 | spin_lock_irq(&ep->lock); |
Davide Libenzi | c7ea763 | 2007-05-15 01:40:47 -0700 | [diff] [blame] | 1211 | if (!ep_is_linked(&epi->rdllink)) { |
| 1212 | list_add_tail(&epi->rdllink, &ep->rdllist); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1213 | |
Davide Libenzi | c7ea763 | 2007-05-15 01:40:47 -0700 | [diff] [blame] | 1214 | /* Notify waiting tasks that events are available */ |
| 1215 | if (waitqueue_active(&ep->wq)) |
Matthew Wilcox | 4a6e9e2 | 2007-08-30 16:10:22 -0400 | [diff] [blame] | 1216 | wake_up_locked(&ep->wq); |
Davide Libenzi | c7ea763 | 2007-05-15 01:40:47 -0700 | [diff] [blame] | 1217 | if (waitqueue_active(&ep->poll_wait)) |
| 1218 | pwake++; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1219 | } |
Tony Battersby | e057e15 | 2009-03-31 15:24:15 -0700 | [diff] [blame] | 1220 | spin_unlock_irq(&ep->lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1221 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1222 | |
| 1223 | /* We have to call this outside the lock */ |
| 1224 | if (pwake) |
Davide Libenzi | 5071f97 | 2009-03-31 15:24:10 -0700 | [diff] [blame] | 1225 | ep_poll_safewake(&ep->poll_wait); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1226 | |
| 1227 | return 0; |
| 1228 | } |
| 1229 | |
Davide Libenzi | 296e236 | 2009-03-31 15:24:11 -0700 | [diff] [blame] | 1230 | static int ep_send_events_proc(struct eventpoll *ep, struct list_head *head, |
| 1231 | void *priv) |
Davide Libenzi | 5071f97 | 2009-03-31 15:24:10 -0700 | [diff] [blame] | 1232 | { |
| 1233 | struct ep_send_events_data *esed = priv; |
| 1234 | int eventcnt; |
Davide Libenzi | 296e236 | 2009-03-31 15:24:11 -0700 | [diff] [blame] | 1235 | unsigned int revents; |
Davide Libenzi | 5071f97 | 2009-03-31 15:24:10 -0700 | [diff] [blame] | 1236 | struct epitem *epi; |
| 1237 | struct epoll_event __user *uevent; |
| 1238 | |
Davide Libenzi | 296e236 | 2009-03-31 15:24:11 -0700 | [diff] [blame] | 1239 | /* |
Davide Libenzi | 5071f97 | 2009-03-31 15:24:10 -0700 | [diff] [blame] | 1240 | * We can loop without lock because we are passed a task private list. |
| 1241 | * Items cannot vanish during the loop because ep_scan_ready_list() is |
| 1242 | * holding "mtx" during this call. |
Davide Libenzi | 296e236 | 2009-03-31 15:24:11 -0700 | [diff] [blame] | 1243 | */ |
Davide Libenzi | 5071f97 | 2009-03-31 15:24:10 -0700 | [diff] [blame] | 1244 | for (eventcnt = 0, uevent = esed->events; |
| 1245 | !list_empty(head) && eventcnt < esed->maxevents;) { |
| 1246 | epi = list_first_entry(head, struct epitem, rdllink); |
| 1247 | |
| 1248 | list_del_init(&epi->rdllink); |
| 1249 | |
Davide Libenzi | 296e236 | 2009-03-31 15:24:11 -0700 | [diff] [blame] | 1250 | revents = epi->ffd.file->f_op->poll(epi->ffd.file, NULL) & |
| 1251 | epi->event.events; |
Davide Libenzi | 5071f97 | 2009-03-31 15:24:10 -0700 | [diff] [blame] | 1252 | |
Davide Libenzi | 296e236 | 2009-03-31 15:24:11 -0700 | [diff] [blame] | 1253 | /* |
Davide Libenzi | 5071f97 | 2009-03-31 15:24:10 -0700 | [diff] [blame] | 1254 | * If the event mask intersect the caller-requested one, |
| 1255 | * deliver the event to userspace. Again, ep_scan_ready_list() |
| 1256 | * is holding "mtx", so no operations coming from userspace |
| 1257 | * can change the item. |
Davide Libenzi | 296e236 | 2009-03-31 15:24:11 -0700 | [diff] [blame] | 1258 | */ |
| 1259 | if (revents) { |
Davide Libenzi | 5071f97 | 2009-03-31 15:24:10 -0700 | [diff] [blame] | 1260 | if (__put_user(revents, &uevent->events) || |
Tony Battersby | d030588 | 2009-03-31 15:24:14 -0700 | [diff] [blame] | 1261 | __put_user(epi->event.data, &uevent->data)) { |
| 1262 | list_add(&epi->rdllink, head); |
Davide Libenzi | 296e236 | 2009-03-31 15:24:11 -0700 | [diff] [blame] | 1263 | return eventcnt ? eventcnt : -EFAULT; |
Tony Battersby | d030588 | 2009-03-31 15:24:14 -0700 | [diff] [blame] | 1264 | } |
Davide Libenzi | 296e236 | 2009-03-31 15:24:11 -0700 | [diff] [blame] | 1265 | eventcnt++; |
Davide Libenzi | 5071f97 | 2009-03-31 15:24:10 -0700 | [diff] [blame] | 1266 | uevent++; |
Davide Libenzi | 296e236 | 2009-03-31 15:24:11 -0700 | [diff] [blame] | 1267 | if (epi->event.events & EPOLLONESHOT) |
| 1268 | epi->event.events &= EP_PRIVATE_BITS; |
| 1269 | else if (!(epi->event.events & EPOLLET)) { |
| 1270 | /* |
| 1271 | * If this file has been added with Level |
| 1272 | * Trigger mode, we need to insert back inside |
| 1273 | * the ready list, so that the next call to |
| 1274 | * epoll_wait() will check again the events |
Lucas De Marchi | 25985ed | 2011-03-30 22:57:33 -0300 | [diff] [blame] | 1275 | * availability. At this point, no one can insert |
Davide Libenzi | 296e236 | 2009-03-31 15:24:11 -0700 | [diff] [blame] | 1276 | * into ep->rdllist besides us. The epoll_ctl() |
| 1277 | * callers are locked out by |
| 1278 | * ep_scan_ready_list() holding "mtx" and the |
| 1279 | * poll callback will queue them in ep->ovflist. |
| 1280 | */ |
| 1281 | list_add_tail(&epi->rdllink, &ep->rdllist); |
| 1282 | } |
| 1283 | } |
| 1284 | } |
Davide Libenzi | 5071f97 | 2009-03-31 15:24:10 -0700 | [diff] [blame] | 1285 | |
| 1286 | return eventcnt; |
| 1287 | } |
| 1288 | |
Davide Libenzi | 296e236 | 2009-03-31 15:24:11 -0700 | [diff] [blame] | 1289 | static int ep_send_events(struct eventpoll *ep, |
| 1290 | struct epoll_event __user *events, int maxevents) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1291 | { |
Davide Libenzi | 5071f97 | 2009-03-31 15:24:10 -0700 | [diff] [blame] | 1292 | struct ep_send_events_data esed; |
Davide Libenzi | 6192bd5 | 2007-05-08 00:25:41 -0700 | [diff] [blame] | 1293 | |
Davide Libenzi | 5071f97 | 2009-03-31 15:24:10 -0700 | [diff] [blame] | 1294 | esed.maxevents = maxevents; |
| 1295 | esed.events = events; |
Davide Libenzi | d47de16 | 2007-05-15 01:40:41 -0700 | [diff] [blame] | 1296 | |
Nelson Elhage | d8805e6 | 2011-10-31 17:13:14 -0700 | [diff] [blame] | 1297 | return ep_scan_ready_list(ep, ep_send_events_proc, &esed, 0); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1298 | } |
| 1299 | |
Eric Dumazet | 0781b90 | 2011-02-01 15:52:35 -0800 | [diff] [blame] | 1300 | static inline struct timespec ep_set_mstimeout(long ms) |
| 1301 | { |
| 1302 | struct timespec now, ts = { |
| 1303 | .tv_sec = ms / MSEC_PER_SEC, |
| 1304 | .tv_nsec = NSEC_PER_MSEC * (ms % MSEC_PER_SEC), |
| 1305 | }; |
| 1306 | |
| 1307 | ktime_get_ts(&now); |
| 1308 | return timespec_add_safe(now, ts); |
| 1309 | } |
| 1310 | |
Shawn Bohrer | f4d93ad | 2011-03-22 16:34:47 -0700 | [diff] [blame] | 1311 | /** |
| 1312 | * ep_poll - Retrieves ready events, and delivers them to the caller supplied |
| 1313 | * event buffer. |
| 1314 | * |
| 1315 | * @ep: Pointer to the eventpoll context. |
| 1316 | * @events: Pointer to the userspace buffer where the ready events should be |
| 1317 | * stored. |
| 1318 | * @maxevents: Size (in terms of number of events) of the caller event buffer. |
| 1319 | * @timeout: Maximum timeout for the ready events fetch operation, in |
| 1320 | * milliseconds. If the @timeout is zero, the function will not block, |
| 1321 | * while if the @timeout is less than zero, the function will block |
| 1322 | * until at least one event has been retrieved (or an error |
| 1323 | * occurred). |
| 1324 | * |
| 1325 | * Returns: Returns the number of ready events which have been fetched, or an |
| 1326 | * error code, in case of error. |
| 1327 | */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1328 | static int ep_poll(struct eventpoll *ep, struct epoll_event __user *events, |
| 1329 | int maxevents, long timeout) |
| 1330 | { |
Shawn Bohrer | f4d93ad | 2011-03-22 16:34:47 -0700 | [diff] [blame] | 1331 | int res = 0, eavail, timed_out = 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1332 | unsigned long flags; |
Shawn Bohrer | f4d93ad | 2011-03-22 16:34:47 -0700 | [diff] [blame] | 1333 | long slack = 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1334 | wait_queue_t wait; |
Shawn Bohrer | 95aac7b | 2010-10-27 15:34:54 -0700 | [diff] [blame] | 1335 | ktime_t expires, *to = NULL; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1336 | |
Shawn Bohrer | 95aac7b | 2010-10-27 15:34:54 -0700 | [diff] [blame] | 1337 | if (timeout > 0) { |
Eric Dumazet | 0781b90 | 2011-02-01 15:52:35 -0800 | [diff] [blame] | 1338 | struct timespec end_time = ep_set_mstimeout(timeout); |
| 1339 | |
Shawn Bohrer | 95aac7b | 2010-10-27 15:34:54 -0700 | [diff] [blame] | 1340 | slack = select_estimate_accuracy(&end_time); |
| 1341 | to = &expires; |
| 1342 | *to = timespec_to_ktime(end_time); |
| 1343 | } else if (timeout == 0) { |
Shawn Bohrer | f4d93ad | 2011-03-22 16:34:47 -0700 | [diff] [blame] | 1344 | /* |
| 1345 | * Avoid the unnecessary trip to the wait queue loop, if the |
| 1346 | * caller specified a non blocking operation. |
| 1347 | */ |
Shawn Bohrer | 95aac7b | 2010-10-27 15:34:54 -0700 | [diff] [blame] | 1348 | timed_out = 1; |
Shawn Bohrer | f4d93ad | 2011-03-22 16:34:47 -0700 | [diff] [blame] | 1349 | spin_lock_irqsave(&ep->lock, flags); |
| 1350 | goto check_events; |
Shawn Bohrer | 95aac7b | 2010-10-27 15:34:54 -0700 | [diff] [blame] | 1351 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1352 | |
Shawn Bohrer | f4d93ad | 2011-03-22 16:34:47 -0700 | [diff] [blame] | 1353 | fetch_events: |
Davide Libenzi | c7ea763 | 2007-05-15 01:40:47 -0700 | [diff] [blame] | 1354 | spin_lock_irqsave(&ep->lock, flags); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1355 | |
Davide Libenzi | 3fb0e58 | 2011-03-22 16:34:46 -0700 | [diff] [blame] | 1356 | if (!ep_events_available(ep)) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1357 | /* |
| 1358 | * We don't have any available event to return to the caller. |
| 1359 | * We need to sleep here, and we will be wake up by |
| 1360 | * ep_poll_callback() when events will become available. |
| 1361 | */ |
| 1362 | init_waitqueue_entry(&wait, current); |
Changli Gao | a93d2f1 | 2010-05-07 14:33:26 +0800 | [diff] [blame] | 1363 | __add_wait_queue_exclusive(&ep->wq, &wait); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1364 | |
| 1365 | for (;;) { |
| 1366 | /* |
| 1367 | * We don't want to sleep if the ep_poll_callback() sends us |
| 1368 | * a wakeup in between. That's why we set the task state |
| 1369 | * to TASK_INTERRUPTIBLE before doing the checks. |
| 1370 | */ |
| 1371 | set_current_state(TASK_INTERRUPTIBLE); |
Davide Libenzi | 3fb0e58 | 2011-03-22 16:34:46 -0700 | [diff] [blame] | 1372 | if (ep_events_available(ep) || timed_out) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1373 | break; |
| 1374 | if (signal_pending(current)) { |
| 1375 | res = -EINTR; |
| 1376 | break; |
| 1377 | } |
| 1378 | |
Davide Libenzi | c7ea763 | 2007-05-15 01:40:47 -0700 | [diff] [blame] | 1379 | spin_unlock_irqrestore(&ep->lock, flags); |
Shawn Bohrer | 95aac7b | 2010-10-27 15:34:54 -0700 | [diff] [blame] | 1380 | if (!schedule_hrtimeout_range(to, slack, HRTIMER_MODE_ABS)) |
| 1381 | timed_out = 1; |
| 1382 | |
Davide Libenzi | c7ea763 | 2007-05-15 01:40:47 -0700 | [diff] [blame] | 1383 | spin_lock_irqsave(&ep->lock, flags); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1384 | } |
Davide Libenzi | 3419b23 | 2006-06-25 05:48:14 -0700 | [diff] [blame] | 1385 | __remove_wait_queue(&ep->wq, &wait); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1386 | |
| 1387 | set_current_state(TASK_RUNNING); |
| 1388 | } |
Shawn Bohrer | f4d93ad | 2011-03-22 16:34:47 -0700 | [diff] [blame] | 1389 | check_events: |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1390 | /* Is it worth to try to dig for events ? */ |
Davide Libenzi | 3fb0e58 | 2011-03-22 16:34:46 -0700 | [diff] [blame] | 1391 | eavail = ep_events_available(ep); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1392 | |
Davide Libenzi | c7ea763 | 2007-05-15 01:40:47 -0700 | [diff] [blame] | 1393 | spin_unlock_irqrestore(&ep->lock, flags); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1394 | |
| 1395 | /* |
| 1396 | * Try to transfer events to user space. In case we get 0 events and |
| 1397 | * there's still timeout left over, we go trying again in search of |
| 1398 | * more luck. |
| 1399 | */ |
| 1400 | if (!res && eavail && |
Shawn Bohrer | 95aac7b | 2010-10-27 15:34:54 -0700 | [diff] [blame] | 1401 | !(res = ep_send_events(ep, events, maxevents)) && !timed_out) |
Shawn Bohrer | f4d93ad | 2011-03-22 16:34:47 -0700 | [diff] [blame] | 1402 | goto fetch_events; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1403 | |
| 1404 | return res; |
| 1405 | } |
| 1406 | |
Davide Libenzi | 22bacca | 2011-02-25 14:44:12 -0800 | [diff] [blame] | 1407 | /** |
| 1408 | * ep_loop_check_proc - Callback function to be passed to the @ep_call_nested() |
| 1409 | * API, to verify that adding an epoll file inside another |
| 1410 | * epoll structure, does not violate the constraints, in |
| 1411 | * terms of closed loops, or too deep chains (which can |
| 1412 | * result in excessive stack usage). |
| 1413 | * |
| 1414 | * @priv: Pointer to the epoll file to be currently checked. |
| 1415 | * @cookie: Original cookie for this call. This is the top-of-the-chain epoll |
| 1416 | * data structure pointer. |
| 1417 | * @call_nests: Current dept of the @ep_call_nested() call stack. |
| 1418 | * |
| 1419 | * Returns: Returns zero if adding the epoll @file inside current epoll |
| 1420 | * structure @ep does not violate the constraints, or -1 otherwise. |
| 1421 | */ |
| 1422 | static int ep_loop_check_proc(void *priv, void *cookie, int call_nests) |
| 1423 | { |
| 1424 | int error = 0; |
| 1425 | struct file *file = priv; |
| 1426 | struct eventpoll *ep = file->private_data; |
Jason Baron | 28d82dc | 2012-01-12 17:17:43 -0800 | [diff] [blame] | 1427 | struct eventpoll *ep_tovisit; |
Davide Libenzi | 22bacca | 2011-02-25 14:44:12 -0800 | [diff] [blame] | 1428 | struct rb_node *rbp; |
| 1429 | struct epitem *epi; |
| 1430 | |
Nelson Elhage | d8805e6 | 2011-10-31 17:13:14 -0700 | [diff] [blame] | 1431 | mutex_lock_nested(&ep->mtx, call_nests + 1); |
Jason Baron | 28d82dc | 2012-01-12 17:17:43 -0800 | [diff] [blame] | 1432 | ep->visited = 1; |
| 1433 | list_add(&ep->visited_list_link, &visited_list); |
Davide Libenzi | 22bacca | 2011-02-25 14:44:12 -0800 | [diff] [blame] | 1434 | for (rbp = rb_first(&ep->rbr); rbp; rbp = rb_next(rbp)) { |
| 1435 | epi = rb_entry(rbp, struct epitem, rbn); |
| 1436 | if (unlikely(is_file_epoll(epi->ffd.file))) { |
Jason Baron | 28d82dc | 2012-01-12 17:17:43 -0800 | [diff] [blame] | 1437 | ep_tovisit = epi->ffd.file->private_data; |
| 1438 | if (ep_tovisit->visited) |
| 1439 | continue; |
Davide Libenzi | 22bacca | 2011-02-25 14:44:12 -0800 | [diff] [blame] | 1440 | error = ep_call_nested(&poll_loop_ncalls, EP_MAX_NESTS, |
Jason Baron | 28d82dc | 2012-01-12 17:17:43 -0800 | [diff] [blame] | 1441 | ep_loop_check_proc, epi->ffd.file, |
| 1442 | ep_tovisit, current); |
Davide Libenzi | 22bacca | 2011-02-25 14:44:12 -0800 | [diff] [blame] | 1443 | if (error != 0) |
| 1444 | break; |
Jason Baron | 28d82dc | 2012-01-12 17:17:43 -0800 | [diff] [blame] | 1445 | } else { |
| 1446 | /* |
| 1447 | * If we've reached a file that is not associated with |
| 1448 | * an ep, then we need to check if the newly added |
| 1449 | * links are going to add too many wakeup paths. We do |
| 1450 | * this by adding it to the tfile_check_list, if it's |
| 1451 | * not already there, and calling reverse_path_check() |
| 1452 | * during ep_insert(). |
| 1453 | */ |
| 1454 | if (list_empty(&epi->ffd.file->f_tfile_llink)) |
| 1455 | list_add(&epi->ffd.file->f_tfile_llink, |
| 1456 | &tfile_check_list); |
Davide Libenzi | 22bacca | 2011-02-25 14:44:12 -0800 | [diff] [blame] | 1457 | } |
| 1458 | } |
| 1459 | mutex_unlock(&ep->mtx); |
| 1460 | |
| 1461 | return error; |
| 1462 | } |
| 1463 | |
| 1464 | /** |
| 1465 | * ep_loop_check - Performs a check to verify that adding an epoll file (@file) |
| 1466 | * another epoll file (represented by @ep) does not create |
| 1467 | * closed loops or too deep chains. |
| 1468 | * |
| 1469 | * @ep: Pointer to the epoll private data structure. |
| 1470 | * @file: Pointer to the epoll file to be checked. |
| 1471 | * |
| 1472 | * Returns: Returns zero if adding the epoll @file inside current epoll |
| 1473 | * structure @ep does not violate the constraints, or -1 otherwise. |
| 1474 | */ |
| 1475 | static int ep_loop_check(struct eventpoll *ep, struct file *file) |
| 1476 | { |
Jason Baron | 28d82dc | 2012-01-12 17:17:43 -0800 | [diff] [blame] | 1477 | int ret; |
| 1478 | struct eventpoll *ep_cur, *ep_next; |
| 1479 | |
| 1480 | ret = ep_call_nested(&poll_loop_ncalls, EP_MAX_NESTS, |
Davide Libenzi | 22bacca | 2011-02-25 14:44:12 -0800 | [diff] [blame] | 1481 | ep_loop_check_proc, file, ep, current); |
Jason Baron | 28d82dc | 2012-01-12 17:17:43 -0800 | [diff] [blame] | 1482 | /* clear visited list */ |
| 1483 | list_for_each_entry_safe(ep_cur, ep_next, &visited_list, |
| 1484 | visited_list_link) { |
| 1485 | ep_cur->visited = 0; |
| 1486 | list_del(&ep_cur->visited_list_link); |
| 1487 | } |
| 1488 | return ret; |
| 1489 | } |
| 1490 | |
| 1491 | static void clear_tfile_check_list(void) |
| 1492 | { |
| 1493 | struct file *file; |
| 1494 | |
| 1495 | /* first clear the tfile_check_list */ |
| 1496 | while (!list_empty(&tfile_check_list)) { |
| 1497 | file = list_first_entry(&tfile_check_list, struct file, |
| 1498 | f_tfile_llink); |
| 1499 | list_del_init(&file->f_tfile_llink); |
| 1500 | } |
| 1501 | INIT_LIST_HEAD(&tfile_check_list); |
Davide Libenzi | 22bacca | 2011-02-25 14:44:12 -0800 | [diff] [blame] | 1502 | } |
| 1503 | |
Davide Libenzi | 7699acd | 2007-05-10 22:23:23 -0700 | [diff] [blame] | 1504 | /* |
Andrew Morton | 523723b | 2008-08-12 15:09:01 -0700 | [diff] [blame] | 1505 | * Open an eventpoll file descriptor. |
Davide Libenzi | 7699acd | 2007-05-10 22:23:23 -0700 | [diff] [blame] | 1506 | */ |
Heiko Carstens | 5a8a82b | 2009-01-14 14:14:25 +0100 | [diff] [blame] | 1507 | SYSCALL_DEFINE1(epoll_create1, int, flags) |
Davide Libenzi | 7699acd | 2007-05-10 22:23:23 -0700 | [diff] [blame] | 1508 | { |
Jason Baron | 28d82dc | 2012-01-12 17:17:43 -0800 | [diff] [blame] | 1509 | int error, fd; |
Davide Libenzi | bb57c3e | 2009-03-31 15:24:12 -0700 | [diff] [blame] | 1510 | struct eventpoll *ep = NULL; |
Jason Baron | 28d82dc | 2012-01-12 17:17:43 -0800 | [diff] [blame] | 1511 | struct file *file; |
Davide Libenzi | 7699acd | 2007-05-10 22:23:23 -0700 | [diff] [blame] | 1512 | |
Ulrich Drepper | e38b36f | 2008-07-23 21:29:42 -0700 | [diff] [blame] | 1513 | /* Check the EPOLL_* constant for consistency. */ |
| 1514 | BUILD_BUG_ON(EPOLL_CLOEXEC != O_CLOEXEC); |
| 1515 | |
Davide Libenzi | 296e236 | 2009-03-31 15:24:11 -0700 | [diff] [blame] | 1516 | if (flags & ~EPOLL_CLOEXEC) |
| 1517 | return -EINVAL; |
Davide Libenzi | 7699acd | 2007-05-10 22:23:23 -0700 | [diff] [blame] | 1518 | /* |
Davide Libenzi | bb57c3e | 2009-03-31 15:24:12 -0700 | [diff] [blame] | 1519 | * Create the internal data structure ("struct eventpoll"). |
Davide Libenzi | 7699acd | 2007-05-10 22:23:23 -0700 | [diff] [blame] | 1520 | */ |
Ulrich Drepper | 9fe5ad9 | 2008-07-23 21:29:43 -0700 | [diff] [blame] | 1521 | error = ep_alloc(&ep); |
Davide Libenzi | bb57c3e | 2009-03-31 15:24:12 -0700 | [diff] [blame] | 1522 | if (error < 0) |
| 1523 | return error; |
Davide Libenzi | 7699acd | 2007-05-10 22:23:23 -0700 | [diff] [blame] | 1524 | /* |
| 1525 | * Creates all the items needed to setup an eventpoll file. That is, |
Al Viro | 2030a42 | 2008-02-23 06:46:49 -0500 | [diff] [blame] | 1526 | * a file structure and a free file descriptor. |
Davide Libenzi | 7699acd | 2007-05-10 22:23:23 -0700 | [diff] [blame] | 1527 | */ |
Jason Baron | 28d82dc | 2012-01-12 17:17:43 -0800 | [diff] [blame] | 1528 | fd = get_unused_fd_flags(O_RDWR | (flags & O_CLOEXEC)); |
| 1529 | if (fd < 0) { |
| 1530 | error = fd; |
| 1531 | goto out_free_ep; |
| 1532 | } |
| 1533 | file = anon_inode_getfile("[eventpoll]", &eventpoll_fops, ep, |
Roland Dreier | 628ff7c | 2009-12-18 09:41:24 -0800 | [diff] [blame] | 1534 | O_RDWR | (flags & O_CLOEXEC)); |
Jason Baron | 28d82dc | 2012-01-12 17:17:43 -0800 | [diff] [blame] | 1535 | if (IS_ERR(file)) { |
| 1536 | error = PTR_ERR(file); |
| 1537 | goto out_free_fd; |
| 1538 | } |
| 1539 | fd_install(fd, file); |
| 1540 | ep->file = file; |
| 1541 | return fd; |
Davide Libenzi | 7699acd | 2007-05-10 22:23:23 -0700 | [diff] [blame] | 1542 | |
Jason Baron | 28d82dc | 2012-01-12 17:17:43 -0800 | [diff] [blame] | 1543 | out_free_fd: |
| 1544 | put_unused_fd(fd); |
| 1545 | out_free_ep: |
| 1546 | ep_free(ep); |
Davide Libenzi | bb57c3e | 2009-03-31 15:24:12 -0700 | [diff] [blame] | 1547 | return error; |
Davide Libenzi | 7699acd | 2007-05-10 22:23:23 -0700 | [diff] [blame] | 1548 | } |
| 1549 | |
Heiko Carstens | 5a8a82b | 2009-01-14 14:14:25 +0100 | [diff] [blame] | 1550 | SYSCALL_DEFINE1(epoll_create, int, size) |
Ulrich Drepper | a0998b5 | 2008-07-23 21:29:27 -0700 | [diff] [blame] | 1551 | { |
Davide Libenzi | bfe3891 | 2009-05-12 13:19:44 -0700 | [diff] [blame] | 1552 | if (size <= 0) |
Ulrich Drepper | 9fe5ad9 | 2008-07-23 21:29:43 -0700 | [diff] [blame] | 1553 | return -EINVAL; |
| 1554 | |
| 1555 | return sys_epoll_create1(0); |
Ulrich Drepper | a0998b5 | 2008-07-23 21:29:27 -0700 | [diff] [blame] | 1556 | } |
| 1557 | |
Davide Libenzi | 7699acd | 2007-05-10 22:23:23 -0700 | [diff] [blame] | 1558 | /* |
| 1559 | * The following function implements the controller interface for |
| 1560 | * the eventpoll file that enables the insertion/removal/change of |
Davide Libenzi | 67647d0 | 2007-05-15 01:40:52 -0700 | [diff] [blame] | 1561 | * file descriptors inside the interest set. |
Davide Libenzi | 7699acd | 2007-05-10 22:23:23 -0700 | [diff] [blame] | 1562 | */ |
Heiko Carstens | 5a8a82b | 2009-01-14 14:14:25 +0100 | [diff] [blame] | 1563 | SYSCALL_DEFINE4(epoll_ctl, int, epfd, int, op, int, fd, |
| 1564 | struct epoll_event __user *, event) |
Davide Libenzi | 7699acd | 2007-05-10 22:23:23 -0700 | [diff] [blame] | 1565 | { |
| 1566 | int error; |
Davide Libenzi | 22bacca | 2011-02-25 14:44:12 -0800 | [diff] [blame] | 1567 | int did_lock_epmutex = 0; |
Davide Libenzi | 7699acd | 2007-05-10 22:23:23 -0700 | [diff] [blame] | 1568 | struct file *file, *tfile; |
| 1569 | struct eventpoll *ep; |
| 1570 | struct epitem *epi; |
| 1571 | struct epoll_event epds; |
| 1572 | |
Davide Libenzi | 7699acd | 2007-05-10 22:23:23 -0700 | [diff] [blame] | 1573 | error = -EFAULT; |
| 1574 | if (ep_op_has_event(op) && |
| 1575 | copy_from_user(&epds, event, sizeof(struct epoll_event))) |
| 1576 | goto error_return; |
| 1577 | |
| 1578 | /* Get the "struct file *" for the eventpoll file */ |
| 1579 | error = -EBADF; |
| 1580 | file = fget(epfd); |
| 1581 | if (!file) |
| 1582 | goto error_return; |
| 1583 | |
| 1584 | /* Get the "struct file *" for the target file */ |
| 1585 | tfile = fget(fd); |
| 1586 | if (!tfile) |
| 1587 | goto error_fput; |
| 1588 | |
| 1589 | /* The target file descriptor must support poll */ |
| 1590 | error = -EPERM; |
| 1591 | if (!tfile->f_op || !tfile->f_op->poll) |
| 1592 | goto error_tgt_fput; |
| 1593 | |
| 1594 | /* |
| 1595 | * We have to check that the file structure underneath the file descriptor |
| 1596 | * the user passed to us _is_ an eventpoll file. And also we do not permit |
| 1597 | * adding an epoll file descriptor inside itself. |
| 1598 | */ |
| 1599 | error = -EINVAL; |
| 1600 | if (file == tfile || !is_file_epoll(file)) |
| 1601 | goto error_tgt_fput; |
| 1602 | |
| 1603 | /* |
| 1604 | * At this point it is safe to assume that the "private_data" contains |
| 1605 | * our own data structure. |
| 1606 | */ |
| 1607 | ep = file->private_data; |
| 1608 | |
Davide Libenzi | 22bacca | 2011-02-25 14:44:12 -0800 | [diff] [blame] | 1609 | /* |
| 1610 | * When we insert an epoll file descriptor, inside another epoll file |
| 1611 | * descriptor, there is the change of creating closed loops, which are |
Jason Baron | 28d82dc | 2012-01-12 17:17:43 -0800 | [diff] [blame] | 1612 | * better be handled here, than in more critical paths. While we are |
| 1613 | * checking for loops we also determine the list of files reachable |
| 1614 | * and hang them on the tfile_check_list, so we can check that we |
| 1615 | * haven't created too many possible wakeup paths. |
Davide Libenzi | 22bacca | 2011-02-25 14:44:12 -0800 | [diff] [blame] | 1616 | * |
Jason Baron | 28d82dc | 2012-01-12 17:17:43 -0800 | [diff] [blame] | 1617 | * We need to hold the epmutex across both ep_insert and ep_remove |
| 1618 | * b/c we want to make sure we are looking at a coherent view of |
| 1619 | * epoll network. |
Davide Libenzi | 22bacca | 2011-02-25 14:44:12 -0800 | [diff] [blame] | 1620 | */ |
Jason Baron | 28d82dc | 2012-01-12 17:17:43 -0800 | [diff] [blame] | 1621 | if (op == EPOLL_CTL_ADD || op == EPOLL_CTL_DEL) { |
Davide Libenzi | 22bacca | 2011-02-25 14:44:12 -0800 | [diff] [blame] | 1622 | mutex_lock(&epmutex); |
| 1623 | did_lock_epmutex = 1; |
Davide Libenzi | 22bacca | 2011-02-25 14:44:12 -0800 | [diff] [blame] | 1624 | } |
Jason Baron | 28d82dc | 2012-01-12 17:17:43 -0800 | [diff] [blame] | 1625 | if (op == EPOLL_CTL_ADD) { |
| 1626 | if (is_file_epoll(tfile)) { |
| 1627 | error = -ELOOP; |
| 1628 | if (ep_loop_check(ep, tfile) != 0) |
| 1629 | goto error_tgt_fput; |
| 1630 | } else |
| 1631 | list_add(&tfile->f_tfile_llink, &tfile_check_list); |
| 1632 | } |
Davide Libenzi | 22bacca | 2011-02-25 14:44:12 -0800 | [diff] [blame] | 1633 | |
Nelson Elhage | d8805e6 | 2011-10-31 17:13:14 -0700 | [diff] [blame] | 1634 | mutex_lock_nested(&ep->mtx, 0); |
Davide Libenzi | 7699acd | 2007-05-10 22:23:23 -0700 | [diff] [blame] | 1635 | |
Davide Libenzi | 67647d0 | 2007-05-15 01:40:52 -0700 | [diff] [blame] | 1636 | /* |
| 1637 | * Try to lookup the file inside our RB tree, Since we grabbed "mtx" |
| 1638 | * above, we can be sure to be able to use the item looked up by |
| 1639 | * ep_find() till we release the mutex. |
| 1640 | */ |
Davide Libenzi | 7699acd | 2007-05-10 22:23:23 -0700 | [diff] [blame] | 1641 | epi = ep_find(ep, tfile, fd); |
| 1642 | |
| 1643 | error = -EINVAL; |
| 1644 | switch (op) { |
| 1645 | case EPOLL_CTL_ADD: |
| 1646 | if (!epi) { |
| 1647 | epds.events |= POLLERR | POLLHUP; |
Davide Libenzi | 7699acd | 2007-05-10 22:23:23 -0700 | [diff] [blame] | 1648 | error = ep_insert(ep, &epds, tfile, fd); |
| 1649 | } else |
| 1650 | error = -EEXIST; |
Jason Baron | 28d82dc | 2012-01-12 17:17:43 -0800 | [diff] [blame] | 1651 | clear_tfile_check_list(); |
Davide Libenzi | 7699acd | 2007-05-10 22:23:23 -0700 | [diff] [blame] | 1652 | break; |
| 1653 | case EPOLL_CTL_DEL: |
| 1654 | if (epi) |
| 1655 | error = ep_remove(ep, epi); |
| 1656 | else |
| 1657 | error = -ENOENT; |
| 1658 | break; |
| 1659 | case EPOLL_CTL_MOD: |
| 1660 | if (epi) { |
| 1661 | epds.events |= POLLERR | POLLHUP; |
| 1662 | error = ep_modify(ep, epi, &epds); |
| 1663 | } else |
| 1664 | error = -ENOENT; |
| 1665 | break; |
| 1666 | } |
Davide Libenzi | d47de16 | 2007-05-15 01:40:41 -0700 | [diff] [blame] | 1667 | mutex_unlock(&ep->mtx); |
Davide Libenzi | 7699acd | 2007-05-10 22:23:23 -0700 | [diff] [blame] | 1668 | |
| 1669 | error_tgt_fput: |
Jason Baron | 28d82dc | 2012-01-12 17:17:43 -0800 | [diff] [blame] | 1670 | if (did_lock_epmutex) |
Davide Libenzi | 22bacca | 2011-02-25 14:44:12 -0800 | [diff] [blame] | 1671 | mutex_unlock(&epmutex); |
| 1672 | |
Davide Libenzi | 7699acd | 2007-05-10 22:23:23 -0700 | [diff] [blame] | 1673 | fput(tfile); |
| 1674 | error_fput: |
| 1675 | fput(file); |
| 1676 | error_return: |
Davide Libenzi | 7699acd | 2007-05-10 22:23:23 -0700 | [diff] [blame] | 1677 | |
| 1678 | return error; |
| 1679 | } |
| 1680 | |
| 1681 | /* |
| 1682 | * Implement the event wait interface for the eventpoll file. It is the kernel |
| 1683 | * part of the user space epoll_wait(2). |
| 1684 | */ |
Heiko Carstens | 5a8a82b | 2009-01-14 14:14:25 +0100 | [diff] [blame] | 1685 | SYSCALL_DEFINE4(epoll_wait, int, epfd, struct epoll_event __user *, events, |
| 1686 | int, maxevents, int, timeout) |
Davide Libenzi | 7699acd | 2007-05-10 22:23:23 -0700 | [diff] [blame] | 1687 | { |
| 1688 | int error; |
| 1689 | struct file *file; |
| 1690 | struct eventpoll *ep; |
| 1691 | |
Davide Libenzi | 7699acd | 2007-05-10 22:23:23 -0700 | [diff] [blame] | 1692 | /* The maximum number of event must be greater than zero */ |
| 1693 | if (maxevents <= 0 || maxevents > EP_MAX_EVENTS) |
| 1694 | return -EINVAL; |
| 1695 | |
| 1696 | /* Verify that the area passed by the user is writeable */ |
| 1697 | if (!access_ok(VERIFY_WRITE, events, maxevents * sizeof(struct epoll_event))) { |
| 1698 | error = -EFAULT; |
| 1699 | goto error_return; |
| 1700 | } |
| 1701 | |
| 1702 | /* Get the "struct file *" for the eventpoll file */ |
| 1703 | error = -EBADF; |
| 1704 | file = fget(epfd); |
| 1705 | if (!file) |
| 1706 | goto error_return; |
| 1707 | |
| 1708 | /* |
| 1709 | * We have to check that the file structure underneath the fd |
| 1710 | * the user passed to us _is_ an eventpoll file. |
| 1711 | */ |
| 1712 | error = -EINVAL; |
| 1713 | if (!is_file_epoll(file)) |
| 1714 | goto error_fput; |
| 1715 | |
| 1716 | /* |
| 1717 | * At this point it is safe to assume that the "private_data" contains |
| 1718 | * our own data structure. |
| 1719 | */ |
| 1720 | ep = file->private_data; |
| 1721 | |
| 1722 | /* Time to fish for events ... */ |
| 1723 | error = ep_poll(ep, events, maxevents, timeout); |
| 1724 | |
| 1725 | error_fput: |
| 1726 | fput(file); |
| 1727 | error_return: |
Davide Libenzi | 7699acd | 2007-05-10 22:23:23 -0700 | [diff] [blame] | 1728 | |
| 1729 | return error; |
| 1730 | } |
| 1731 | |
Roland McGrath | f3de272 | 2008-04-30 00:53:09 -0700 | [diff] [blame] | 1732 | #ifdef HAVE_SET_RESTORE_SIGMASK |
Davide Libenzi | 7699acd | 2007-05-10 22:23:23 -0700 | [diff] [blame] | 1733 | |
| 1734 | /* |
| 1735 | * Implement the event wait interface for the eventpoll file. It is the kernel |
| 1736 | * part of the user space epoll_pwait(2). |
| 1737 | */ |
Heiko Carstens | 5a8a82b | 2009-01-14 14:14:25 +0100 | [diff] [blame] | 1738 | SYSCALL_DEFINE6(epoll_pwait, int, epfd, struct epoll_event __user *, events, |
| 1739 | int, maxevents, int, timeout, const sigset_t __user *, sigmask, |
| 1740 | size_t, sigsetsize) |
Davide Libenzi | 7699acd | 2007-05-10 22:23:23 -0700 | [diff] [blame] | 1741 | { |
| 1742 | int error; |
| 1743 | sigset_t ksigmask, sigsaved; |
| 1744 | |
| 1745 | /* |
| 1746 | * If the caller wants a certain signal mask to be set during the wait, |
| 1747 | * we apply it here. |
| 1748 | */ |
| 1749 | if (sigmask) { |
| 1750 | if (sigsetsize != sizeof(sigset_t)) |
| 1751 | return -EINVAL; |
| 1752 | if (copy_from_user(&ksigmask, sigmask, sizeof(ksigmask))) |
| 1753 | return -EFAULT; |
| 1754 | sigdelsetmask(&ksigmask, sigmask(SIGKILL) | sigmask(SIGSTOP)); |
| 1755 | sigprocmask(SIG_SETMASK, &ksigmask, &sigsaved); |
| 1756 | } |
| 1757 | |
| 1758 | error = sys_epoll_wait(epfd, events, maxevents, timeout); |
| 1759 | |
| 1760 | /* |
| 1761 | * If we changed the signal mask, we need to restore the original one. |
| 1762 | * In case we've got a signal while waiting, we do not restore the |
| 1763 | * signal mask yet, and we allow do_signal() to deliver the signal on |
| 1764 | * the way back to userspace, before the signal mask is restored. |
| 1765 | */ |
| 1766 | if (sigmask) { |
| 1767 | if (error == -EINTR) { |
| 1768 | memcpy(¤t->saved_sigmask, &sigsaved, |
Davide Libenzi | c7ea763 | 2007-05-15 01:40:47 -0700 | [diff] [blame] | 1769 | sizeof(sigsaved)); |
Roland McGrath | 4e4c22c | 2008-04-30 00:53:06 -0700 | [diff] [blame] | 1770 | set_restore_sigmask(); |
Davide Libenzi | 7699acd | 2007-05-10 22:23:23 -0700 | [diff] [blame] | 1771 | } else |
| 1772 | sigprocmask(SIG_SETMASK, &sigsaved, NULL); |
| 1773 | } |
| 1774 | |
| 1775 | return error; |
| 1776 | } |
| 1777 | |
Roland McGrath | f3de272 | 2008-04-30 00:53:09 -0700 | [diff] [blame] | 1778 | #endif /* HAVE_SET_RESTORE_SIGMASK */ |
Davide Libenzi | 7699acd | 2007-05-10 22:23:23 -0700 | [diff] [blame] | 1779 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1780 | static int __init eventpoll_init(void) |
| 1781 | { |
Davide Libenzi | 7ef9964 | 2008-12-01 13:13:55 -0800 | [diff] [blame] | 1782 | struct sysinfo si; |
| 1783 | |
| 1784 | si_meminfo(&si); |
Davide Libenzi | 9df04e1 | 2009-01-29 14:25:26 -0800 | [diff] [blame] | 1785 | /* |
| 1786 | * Allows top 4% of lomem to be allocated for epoll watches (per user). |
| 1787 | */ |
| 1788 | max_user_watches = (((si.totalram - si.totalhigh) / 25) << PAGE_SHIFT) / |
Davide Libenzi | 7ef9964 | 2008-12-01 13:13:55 -0800 | [diff] [blame] | 1789 | EP_ITEM_COST; |
Robin Holt | 52bd19f7 | 2011-01-12 17:00:01 -0800 | [diff] [blame] | 1790 | BUG_ON(max_user_watches < 0); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1791 | |
Davide Libenzi | 22bacca | 2011-02-25 14:44:12 -0800 | [diff] [blame] | 1792 | /* |
| 1793 | * Initialize the structure used to perform epoll file descriptor |
| 1794 | * inclusion loops checks. |
| 1795 | */ |
| 1796 | ep_nested_calls_init(&poll_loop_ncalls); |
| 1797 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1798 | /* Initialize the structure used to perform safe poll wait head wake ups */ |
Davide Libenzi | 5071f97 | 2009-03-31 15:24:10 -0700 | [diff] [blame] | 1799 | ep_nested_calls_init(&poll_safewake_ncalls); |
| 1800 | |
| 1801 | /* Initialize the structure used to perform file's f_op->poll() calls */ |
| 1802 | ep_nested_calls_init(&poll_readywalk_ncalls); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1803 | |
| 1804 | /* Allocates slab cache used to allocate "struct epitem" items */ |
| 1805 | epi_cache = kmem_cache_create("eventpoll_epi", sizeof(struct epitem), |
Davide Libenzi | bb57c3e | 2009-03-31 15:24:12 -0700 | [diff] [blame] | 1806 | 0, SLAB_HWCACHE_ALIGN | SLAB_PANIC, NULL); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1807 | |
| 1808 | /* Allocates slab cache used to allocate "struct eppoll_entry" */ |
| 1809 | pwq_cache = kmem_cache_create("eventpoll_pwq", |
Davide Libenzi | bb57c3e | 2009-03-31 15:24:12 -0700 | [diff] [blame] | 1810 | sizeof(struct eppoll_entry), 0, SLAB_PANIC, NULL); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1811 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1812 | return 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1813 | } |
Davide Libenzi | cea6924 | 2007-05-10 22:23:22 -0700 | [diff] [blame] | 1814 | fs_initcall(eventpoll_init); |