Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* |
| 2 | * Generic pidhash and scalable, time-bounded PID allocator |
| 3 | * |
| 4 | * (C) 2002-2003 William Irwin, IBM |
| 5 | * (C) 2004 William Irwin, Oracle |
| 6 | * (C) 2002-2004 Ingo Molnar, Red Hat |
| 7 | * |
| 8 | * pid-structures are backing objects for tasks sharing a given ID to chain |
| 9 | * against. There is very little to them aside from hashing them and |
| 10 | * parking tasks using given ID's on a list. |
| 11 | * |
| 12 | * The hash is always changed with the tasklist_lock write-acquired, |
| 13 | * and the hash is only accessed with the tasklist_lock at least |
| 14 | * read-acquired, so there's no additional SMP locking needed here. |
| 15 | * |
| 16 | * We have a list of bitmap pages, which bitmaps represent the PID space. |
| 17 | * Allocating and freeing PIDs is completely lockless. The worst-case |
| 18 | * allocation scenario when all but one out of 1 million PIDs possible are |
| 19 | * allocated already: the scanning of 32 list entries and at most PAGE_SIZE |
| 20 | * bytes. The typical fastpath is a single successful setbit. Freeing is O(1). |
| 21 | */ |
| 22 | |
| 23 | #include <linux/mm.h> |
| 24 | #include <linux/module.h> |
| 25 | #include <linux/slab.h> |
| 26 | #include <linux/init.h> |
| 27 | #include <linux/bootmem.h> |
| 28 | #include <linux/hash.h> |
Sukadev Bhattiprolu | 61a58c6 | 2006-12-08 02:37:58 -0800 | [diff] [blame] | 29 | #include <linux/pid_namespace.h> |
Sukadev Bhattiprolu | 820e45d | 2007-05-10 22:23:00 -0700 | [diff] [blame] | 30 | #include <linux/init_task.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 31 | |
| 32 | #define pid_hashfn(nr) hash_long((unsigned long)nr, pidhash_shift) |
Eric W. Biederman | 92476d7 | 2006-03-31 02:31:42 -0800 | [diff] [blame] | 33 | static struct hlist_head *pid_hash; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 34 | static int pidhash_shift; |
Sukadev Bhattiprolu | 820e45d | 2007-05-10 22:23:00 -0700 | [diff] [blame] | 35 | struct pid init_struct_pid = INIT_STRUCT_PID; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 36 | |
| 37 | int pid_max = PID_MAX_DEFAULT; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 38 | |
| 39 | #define RESERVED_PIDS 300 |
| 40 | |
| 41 | int pid_max_min = RESERVED_PIDS + 1; |
| 42 | int pid_max_max = PID_MAX_LIMIT; |
| 43 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 44 | #define BITS_PER_PAGE (PAGE_SIZE*8) |
| 45 | #define BITS_PER_PAGE_MASK (BITS_PER_PAGE-1) |
Sukadev Bhattiprolu | 3fbc964 | 2006-10-02 02:17:24 -0700 | [diff] [blame] | 46 | |
Sukadev Bhattiprolu | 61a58c6 | 2006-12-08 02:37:58 -0800 | [diff] [blame] | 47 | static inline int mk_pid(struct pid_namespace *pid_ns, |
| 48 | struct pidmap *map, int off) |
Sukadev Bhattiprolu | 3fbc964 | 2006-10-02 02:17:24 -0700 | [diff] [blame] | 49 | { |
Sukadev Bhattiprolu | 61a58c6 | 2006-12-08 02:37:58 -0800 | [diff] [blame] | 50 | return (map - pid_ns->pidmap)*BITS_PER_PAGE + off; |
Sukadev Bhattiprolu | 3fbc964 | 2006-10-02 02:17:24 -0700 | [diff] [blame] | 51 | } |
| 52 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 53 | #define find_next_offset(map, off) \ |
| 54 | find_next_zero_bit((map)->page, BITS_PER_PAGE, off) |
| 55 | |
| 56 | /* |
| 57 | * PID-map pages start out as NULL, they get allocated upon |
| 58 | * first use and are never deallocated. This way a low pid_max |
| 59 | * value does not cause lots of bitmaps to be allocated, but |
| 60 | * the scheme scales to up to 4 million PIDs, runtime. |
| 61 | */ |
Sukadev Bhattiprolu | 61a58c6 | 2006-12-08 02:37:58 -0800 | [diff] [blame] | 62 | struct pid_namespace init_pid_ns = { |
Cedric Le Goater | 9a575a9 | 2006-12-08 02:37:59 -0800 | [diff] [blame] | 63 | .kref = { |
| 64 | .refcount = ATOMIC_INIT(2), |
| 65 | }, |
Sukadev Bhattiprolu | 3fbc964 | 2006-10-02 02:17:24 -0700 | [diff] [blame] | 66 | .pidmap = { |
| 67 | [ 0 ... PIDMAP_ENTRIES-1] = { ATOMIC_INIT(BITS_PER_PAGE), NULL } |
| 68 | }, |
Sukadev Bhattiprolu | 84d7378 | 2006-12-08 02:38:01 -0800 | [diff] [blame] | 69 | .last_pid = 0, |
Pavel Emelyanov | faacbfd | 2007-10-18 23:40:04 -0700 | [diff] [blame^] | 70 | .level = 0, |
| 71 | .child_reaper = &init_task, |
Sukadev Bhattiprolu | 3fbc964 | 2006-10-02 02:17:24 -0700 | [diff] [blame] | 72 | }; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 73 | |
Serge E. Hallyn | b460cbc | 2007-10-18 23:39:52 -0700 | [diff] [blame] | 74 | int is_global_init(struct task_struct *tsk) |
| 75 | { |
| 76 | return tsk == init_pid_ns.child_reaper; |
| 77 | } |
| 78 | |
Eric W. Biederman | 92476d7 | 2006-03-31 02:31:42 -0800 | [diff] [blame] | 79 | /* |
| 80 | * Note: disable interrupts while the pidmap_lock is held as an |
| 81 | * interrupt might come in and do read_lock(&tasklist_lock). |
| 82 | * |
| 83 | * If we don't disable interrupts there is a nasty deadlock between |
| 84 | * detach_pid()->free_pid() and another cpu that does |
| 85 | * spin_lock(&pidmap_lock) followed by an interrupt routine that does |
| 86 | * read_lock(&tasklist_lock); |
| 87 | * |
| 88 | * After we clean up the tasklist_lock and know there are no |
| 89 | * irq handlers that take it we can leave the interrupts enabled. |
| 90 | * For now it is easier to be safe than to prove it can't happen. |
| 91 | */ |
Sukadev Bhattiprolu | 3fbc964 | 2006-10-02 02:17:24 -0700 | [diff] [blame] | 92 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 93 | static __cacheline_aligned_in_smp DEFINE_SPINLOCK(pidmap_lock); |
| 94 | |
Sukadev Bhattiprolu | 61a58c6 | 2006-12-08 02:37:58 -0800 | [diff] [blame] | 95 | static fastcall void free_pidmap(struct pid_namespace *pid_ns, int pid) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 96 | { |
Sukadev Bhattiprolu | 61a58c6 | 2006-12-08 02:37:58 -0800 | [diff] [blame] | 97 | struct pidmap *map = pid_ns->pidmap + pid / BITS_PER_PAGE; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 98 | int offset = pid & BITS_PER_PAGE_MASK; |
| 99 | |
| 100 | clear_bit(offset, map->page); |
| 101 | atomic_inc(&map->nr_free); |
| 102 | } |
| 103 | |
Sukadev Bhattiprolu | 61a58c6 | 2006-12-08 02:37:58 -0800 | [diff] [blame] | 104 | static int alloc_pidmap(struct pid_namespace *pid_ns) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 105 | { |
Sukadev Bhattiprolu | 61a58c6 | 2006-12-08 02:37:58 -0800 | [diff] [blame] | 106 | int i, offset, max_scan, pid, last = pid_ns->last_pid; |
Sukadev Bhattiprolu | 6a1f3b8 | 2006-10-02 02:17:20 -0700 | [diff] [blame] | 107 | struct pidmap *map; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 108 | |
| 109 | pid = last + 1; |
| 110 | if (pid >= pid_max) |
| 111 | pid = RESERVED_PIDS; |
| 112 | offset = pid & BITS_PER_PAGE_MASK; |
Sukadev Bhattiprolu | 61a58c6 | 2006-12-08 02:37:58 -0800 | [diff] [blame] | 113 | map = &pid_ns->pidmap[pid/BITS_PER_PAGE]; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 114 | max_scan = (pid_max + BITS_PER_PAGE - 1)/BITS_PER_PAGE - !offset; |
| 115 | for (i = 0; i <= max_scan; ++i) { |
| 116 | if (unlikely(!map->page)) { |
Sukadev Bhattiprolu | 3fbc964 | 2006-10-02 02:17:24 -0700 | [diff] [blame] | 117 | void *page = kzalloc(PAGE_SIZE, GFP_KERNEL); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 118 | /* |
| 119 | * Free the page if someone raced with us |
| 120 | * installing it: |
| 121 | */ |
Eric W. Biederman | 92476d7 | 2006-03-31 02:31:42 -0800 | [diff] [blame] | 122 | spin_lock_irq(&pidmap_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 123 | if (map->page) |
Sukadev Bhattiprolu | 3fbc964 | 2006-10-02 02:17:24 -0700 | [diff] [blame] | 124 | kfree(page); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 125 | else |
Sukadev Bhattiprolu | 3fbc964 | 2006-10-02 02:17:24 -0700 | [diff] [blame] | 126 | map->page = page; |
Eric W. Biederman | 92476d7 | 2006-03-31 02:31:42 -0800 | [diff] [blame] | 127 | spin_unlock_irq(&pidmap_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 128 | if (unlikely(!map->page)) |
| 129 | break; |
| 130 | } |
| 131 | if (likely(atomic_read(&map->nr_free))) { |
| 132 | do { |
| 133 | if (!test_and_set_bit(offset, map->page)) { |
| 134 | atomic_dec(&map->nr_free); |
Sukadev Bhattiprolu | 61a58c6 | 2006-12-08 02:37:58 -0800 | [diff] [blame] | 135 | pid_ns->last_pid = pid; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 136 | return pid; |
| 137 | } |
| 138 | offset = find_next_offset(map, offset); |
Sukadev Bhattiprolu | 61a58c6 | 2006-12-08 02:37:58 -0800 | [diff] [blame] | 139 | pid = mk_pid(pid_ns, map, offset); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 140 | /* |
| 141 | * find_next_offset() found a bit, the pid from it |
| 142 | * is in-bounds, and if we fell back to the last |
| 143 | * bitmap block and the final block was the same |
| 144 | * as the starting point, pid is before last_pid. |
| 145 | */ |
| 146 | } while (offset < BITS_PER_PAGE && pid < pid_max && |
| 147 | (i != max_scan || pid < last || |
| 148 | !((last+1) & BITS_PER_PAGE_MASK))); |
| 149 | } |
Sukadev Bhattiprolu | 61a58c6 | 2006-12-08 02:37:58 -0800 | [diff] [blame] | 150 | if (map < &pid_ns->pidmap[(pid_max-1)/BITS_PER_PAGE]) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 151 | ++map; |
| 152 | offset = 0; |
| 153 | } else { |
Sukadev Bhattiprolu | 61a58c6 | 2006-12-08 02:37:58 -0800 | [diff] [blame] | 154 | map = &pid_ns->pidmap[0]; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 155 | offset = RESERVED_PIDS; |
| 156 | if (unlikely(last == offset)) |
| 157 | break; |
| 158 | } |
Sukadev Bhattiprolu | 61a58c6 | 2006-12-08 02:37:58 -0800 | [diff] [blame] | 159 | pid = mk_pid(pid_ns, map, offset); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 160 | } |
| 161 | return -1; |
| 162 | } |
| 163 | |
Sukadev Bhattiprolu | 61a58c6 | 2006-12-08 02:37:58 -0800 | [diff] [blame] | 164 | static int next_pidmap(struct pid_namespace *pid_ns, int last) |
Eric W. Biederman | 0804ef4 | 2006-10-02 02:17:04 -0700 | [diff] [blame] | 165 | { |
| 166 | int offset; |
Eric W. Biederman | f40f50d | 2006-10-02 02:17:25 -0700 | [diff] [blame] | 167 | struct pidmap *map, *end; |
Eric W. Biederman | 0804ef4 | 2006-10-02 02:17:04 -0700 | [diff] [blame] | 168 | |
| 169 | offset = (last + 1) & BITS_PER_PAGE_MASK; |
Sukadev Bhattiprolu | 61a58c6 | 2006-12-08 02:37:58 -0800 | [diff] [blame] | 170 | map = &pid_ns->pidmap[(last + 1)/BITS_PER_PAGE]; |
| 171 | end = &pid_ns->pidmap[PIDMAP_ENTRIES]; |
Eric W. Biederman | f40f50d | 2006-10-02 02:17:25 -0700 | [diff] [blame] | 172 | for (; map < end; map++, offset = 0) { |
Eric W. Biederman | 0804ef4 | 2006-10-02 02:17:04 -0700 | [diff] [blame] | 173 | if (unlikely(!map->page)) |
| 174 | continue; |
| 175 | offset = find_next_bit((map)->page, BITS_PER_PAGE, offset); |
| 176 | if (offset < BITS_PER_PAGE) |
Sukadev Bhattiprolu | 61a58c6 | 2006-12-08 02:37:58 -0800 | [diff] [blame] | 177 | return mk_pid(pid_ns, map, offset); |
Eric W. Biederman | 0804ef4 | 2006-10-02 02:17:04 -0700 | [diff] [blame] | 178 | } |
| 179 | return -1; |
| 180 | } |
| 181 | |
Eric W. Biederman | 92476d7 | 2006-03-31 02:31:42 -0800 | [diff] [blame] | 182 | fastcall void put_pid(struct pid *pid) |
| 183 | { |
Pavel Emelianov | baf8f0f | 2007-10-18 23:39:48 -0700 | [diff] [blame] | 184 | struct pid_namespace *ns; |
| 185 | |
Eric W. Biederman | 92476d7 | 2006-03-31 02:31:42 -0800 | [diff] [blame] | 186 | if (!pid) |
| 187 | return; |
Pavel Emelianov | baf8f0f | 2007-10-18 23:39:48 -0700 | [diff] [blame] | 188 | |
| 189 | /* FIXME - this must be the namespace this pid lives in */ |
| 190 | ns = &init_pid_ns; |
Eric W. Biederman | 92476d7 | 2006-03-31 02:31:42 -0800 | [diff] [blame] | 191 | if ((atomic_read(&pid->count) == 1) || |
| 192 | atomic_dec_and_test(&pid->count)) |
Pavel Emelianov | baf8f0f | 2007-10-18 23:39:48 -0700 | [diff] [blame] | 193 | kmem_cache_free(ns->pid_cachep, pid); |
Eric W. Biederman | 92476d7 | 2006-03-31 02:31:42 -0800 | [diff] [blame] | 194 | } |
Eric W. Biederman | bbf7314 | 2006-10-02 02:17:11 -0700 | [diff] [blame] | 195 | EXPORT_SYMBOL_GPL(put_pid); |
Eric W. Biederman | 92476d7 | 2006-03-31 02:31:42 -0800 | [diff] [blame] | 196 | |
| 197 | static void delayed_put_pid(struct rcu_head *rhp) |
| 198 | { |
| 199 | struct pid *pid = container_of(rhp, struct pid, rcu); |
| 200 | put_pid(pid); |
| 201 | } |
| 202 | |
| 203 | fastcall void free_pid(struct pid *pid) |
| 204 | { |
| 205 | /* We can be called with write_lock_irq(&tasklist_lock) held */ |
| 206 | unsigned long flags; |
| 207 | |
| 208 | spin_lock_irqsave(&pidmap_lock, flags); |
| 209 | hlist_del_rcu(&pid->pid_chain); |
| 210 | spin_unlock_irqrestore(&pidmap_lock, flags); |
| 211 | |
Serge E. Hallyn | 0f24528 | 2007-01-30 15:28:23 -0600 | [diff] [blame] | 212 | free_pidmap(&init_pid_ns, pid->nr); |
Eric W. Biederman | 92476d7 | 2006-03-31 02:31:42 -0800 | [diff] [blame] | 213 | call_rcu(&pid->rcu, delayed_put_pid); |
| 214 | } |
| 215 | |
| 216 | struct pid *alloc_pid(void) |
| 217 | { |
| 218 | struct pid *pid; |
| 219 | enum pid_type type; |
| 220 | int nr = -1; |
Pavel Emelianov | baf8f0f | 2007-10-18 23:39:48 -0700 | [diff] [blame] | 221 | struct pid_namespace *ns; |
Eric W. Biederman | 92476d7 | 2006-03-31 02:31:42 -0800 | [diff] [blame] | 222 | |
Sukadev Bhattiprolu | 2894d650 | 2007-10-18 23:39:49 -0700 | [diff] [blame] | 223 | ns = task_active_pid_ns(current); |
Pavel Emelianov | baf8f0f | 2007-10-18 23:39:48 -0700 | [diff] [blame] | 224 | pid = kmem_cache_alloc(ns->pid_cachep, GFP_KERNEL); |
Eric W. Biederman | 92476d7 | 2006-03-31 02:31:42 -0800 | [diff] [blame] | 225 | if (!pid) |
| 226 | goto out; |
| 227 | |
Pavel Emelianov | baf8f0f | 2007-10-18 23:39:48 -0700 | [diff] [blame] | 228 | nr = alloc_pidmap(ns); |
Eric W. Biederman | 92476d7 | 2006-03-31 02:31:42 -0800 | [diff] [blame] | 229 | if (nr < 0) |
| 230 | goto out_free; |
| 231 | |
| 232 | atomic_set(&pid->count, 1); |
| 233 | pid->nr = nr; |
| 234 | for (type = 0; type < PIDTYPE_MAX; ++type) |
| 235 | INIT_HLIST_HEAD(&pid->tasks[type]); |
| 236 | |
| 237 | spin_lock_irq(&pidmap_lock); |
| 238 | hlist_add_head_rcu(&pid->pid_chain, &pid_hash[pid_hashfn(pid->nr)]); |
| 239 | spin_unlock_irq(&pidmap_lock); |
| 240 | |
| 241 | out: |
| 242 | return pid; |
| 243 | |
| 244 | out_free: |
Pavel Emelianov | baf8f0f | 2007-10-18 23:39:48 -0700 | [diff] [blame] | 245 | kmem_cache_free(ns->pid_cachep, pid); |
Eric W. Biederman | 92476d7 | 2006-03-31 02:31:42 -0800 | [diff] [blame] | 246 | pid = NULL; |
| 247 | goto out; |
| 248 | } |
| 249 | |
| 250 | struct pid * fastcall find_pid(int nr) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 251 | { |
| 252 | struct hlist_node *elem; |
| 253 | struct pid *pid; |
| 254 | |
Ingo Molnar | e56d090 | 2006-01-08 01:01:37 -0800 | [diff] [blame] | 255 | hlist_for_each_entry_rcu(pid, elem, |
Eric W. Biederman | 92476d7 | 2006-03-31 02:31:42 -0800 | [diff] [blame] | 256 | &pid_hash[pid_hashfn(nr)], pid_chain) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 257 | if (pid->nr == nr) |
| 258 | return pid; |
| 259 | } |
| 260 | return NULL; |
| 261 | } |
Eric W. Biederman | bbf7314 | 2006-10-02 02:17:11 -0700 | [diff] [blame] | 262 | EXPORT_SYMBOL_GPL(find_pid); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 263 | |
Sukadev Bhattiprolu | e713d0d | 2007-05-10 22:22:58 -0700 | [diff] [blame] | 264 | /* |
| 265 | * attach_pid() must be called with the tasklist_lock write-held. |
| 266 | */ |
| 267 | int fastcall attach_pid(struct task_struct *task, enum pid_type type, |
| 268 | struct pid *pid) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 269 | { |
Eric W. Biederman | 92476d7 | 2006-03-31 02:31:42 -0800 | [diff] [blame] | 270 | struct pid_link *link; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 271 | |
Eric W. Biederman | 92476d7 | 2006-03-31 02:31:42 -0800 | [diff] [blame] | 272 | link = &task->pids[type]; |
Sukadev Bhattiprolu | e713d0d | 2007-05-10 22:22:58 -0700 | [diff] [blame] | 273 | link->pid = pid; |
Eric W. Biederman | 92476d7 | 2006-03-31 02:31:42 -0800 | [diff] [blame] | 274 | hlist_add_head_rcu(&link->node, &pid->tasks[type]); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 275 | |
| 276 | return 0; |
| 277 | } |
| 278 | |
Ingo Molnar | 36c8b58 | 2006-07-03 00:25:41 -0700 | [diff] [blame] | 279 | void fastcall detach_pid(struct task_struct *task, enum pid_type type) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 280 | { |
Eric W. Biederman | 92476d7 | 2006-03-31 02:31:42 -0800 | [diff] [blame] | 281 | struct pid_link *link; |
| 282 | struct pid *pid; |
| 283 | int tmp; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 284 | |
Eric W. Biederman | 92476d7 | 2006-03-31 02:31:42 -0800 | [diff] [blame] | 285 | link = &task->pids[type]; |
| 286 | pid = link->pid; |
| 287 | |
| 288 | hlist_del_rcu(&link->node); |
| 289 | link->pid = NULL; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 290 | |
| 291 | for (tmp = PIDTYPE_MAX; --tmp >= 0; ) |
Eric W. Biederman | 92476d7 | 2006-03-31 02:31:42 -0800 | [diff] [blame] | 292 | if (!hlist_empty(&pid->tasks[tmp])) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 293 | return; |
| 294 | |
Eric W. Biederman | 92476d7 | 2006-03-31 02:31:42 -0800 | [diff] [blame] | 295 | free_pid(pid); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 296 | } |
| 297 | |
Eric W. Biederman | c18258c | 2006-09-27 01:51:06 -0700 | [diff] [blame] | 298 | /* transfer_pid is an optimization of attach_pid(new), detach_pid(old) */ |
| 299 | void fastcall transfer_pid(struct task_struct *old, struct task_struct *new, |
| 300 | enum pid_type type) |
| 301 | { |
| 302 | new->pids[type].pid = old->pids[type].pid; |
| 303 | hlist_replace_rcu(&old->pids[type].node, &new->pids[type].node); |
| 304 | old->pids[type].pid = NULL; |
| 305 | } |
| 306 | |
Eric W. Biederman | 92476d7 | 2006-03-31 02:31:42 -0800 | [diff] [blame] | 307 | struct task_struct * fastcall pid_task(struct pid *pid, enum pid_type type) |
| 308 | { |
| 309 | struct task_struct *result = NULL; |
| 310 | if (pid) { |
| 311 | struct hlist_node *first; |
| 312 | first = rcu_dereference(pid->tasks[type].first); |
| 313 | if (first) |
| 314 | result = hlist_entry(first, struct task_struct, pids[(type)].node); |
| 315 | } |
| 316 | return result; |
| 317 | } |
| 318 | |
| 319 | /* |
| 320 | * Must be called under rcu_read_lock() or with tasklist_lock read-held. |
| 321 | */ |
Ingo Molnar | 36c8b58 | 2006-07-03 00:25:41 -0700 | [diff] [blame] | 322 | struct task_struct *find_task_by_pid_type(int type, int nr) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 323 | { |
Eric W. Biederman | 92476d7 | 2006-03-31 02:31:42 -0800 | [diff] [blame] | 324 | return pid_task(find_pid(nr), type); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 325 | } |
| 326 | |
| 327 | EXPORT_SYMBOL(find_task_by_pid_type); |
| 328 | |
Oleg Nesterov | 1a657f78 | 2006-10-02 02:18:59 -0700 | [diff] [blame] | 329 | struct pid *get_task_pid(struct task_struct *task, enum pid_type type) |
| 330 | { |
| 331 | struct pid *pid; |
| 332 | rcu_read_lock(); |
| 333 | pid = get_pid(task->pids[type].pid); |
| 334 | rcu_read_unlock(); |
| 335 | return pid; |
| 336 | } |
| 337 | |
Eric W. Biederman | 92476d7 | 2006-03-31 02:31:42 -0800 | [diff] [blame] | 338 | struct task_struct *fastcall get_pid_task(struct pid *pid, enum pid_type type) |
| 339 | { |
| 340 | struct task_struct *result; |
| 341 | rcu_read_lock(); |
| 342 | result = pid_task(pid, type); |
| 343 | if (result) |
| 344 | get_task_struct(result); |
| 345 | rcu_read_unlock(); |
| 346 | return result; |
| 347 | } |
| 348 | |
| 349 | struct pid *find_get_pid(pid_t nr) |
| 350 | { |
| 351 | struct pid *pid; |
| 352 | |
| 353 | rcu_read_lock(); |
| 354 | pid = get_pid(find_pid(nr)); |
| 355 | rcu_read_unlock(); |
| 356 | |
| 357 | return pid; |
| 358 | } |
| 359 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 360 | /* |
Eric W. Biederman | 0804ef4 | 2006-10-02 02:17:04 -0700 | [diff] [blame] | 361 | * Used by proc to find the first pid that is greater then or equal to nr. |
| 362 | * |
| 363 | * If there is a pid at nr this function is exactly the same as find_pid. |
| 364 | */ |
| 365 | struct pid *find_ge_pid(int nr) |
| 366 | { |
| 367 | struct pid *pid; |
| 368 | |
| 369 | do { |
| 370 | pid = find_pid(nr); |
| 371 | if (pid) |
| 372 | break; |
Sukadev Bhattiprolu | 2894d650 | 2007-10-18 23:39:49 -0700 | [diff] [blame] | 373 | nr = next_pidmap(task_active_pid_ns(current), nr); |
Eric W. Biederman | 0804ef4 | 2006-10-02 02:17:04 -0700 | [diff] [blame] | 374 | } while (nr > 0); |
| 375 | |
| 376 | return pid; |
| 377 | } |
Eric W. Biederman | bbf7314 | 2006-10-02 02:17:11 -0700 | [diff] [blame] | 378 | EXPORT_SYMBOL_GPL(find_get_pid); |
Eric W. Biederman | 0804ef4 | 2006-10-02 02:17:04 -0700 | [diff] [blame] | 379 | |
Pavel Emelianov | baf8f0f | 2007-10-18 23:39:48 -0700 | [diff] [blame] | 380 | struct pid_cache { |
| 381 | int nr_ids; |
| 382 | char name[16]; |
| 383 | struct kmem_cache *cachep; |
| 384 | struct list_head list; |
| 385 | }; |
| 386 | |
| 387 | static LIST_HEAD(pid_caches_lh); |
| 388 | static DEFINE_MUTEX(pid_caches_mutex); |
| 389 | |
| 390 | /* |
| 391 | * creates the kmem cache to allocate pids from. |
| 392 | * @nr_ids: the number of numerical ids this pid will have to carry |
| 393 | */ |
| 394 | |
| 395 | static struct kmem_cache *create_pid_cachep(int nr_ids) |
| 396 | { |
| 397 | struct pid_cache *pcache; |
| 398 | struct kmem_cache *cachep; |
| 399 | |
| 400 | mutex_lock(&pid_caches_mutex); |
| 401 | list_for_each_entry (pcache, &pid_caches_lh, list) |
| 402 | if (pcache->nr_ids == nr_ids) |
| 403 | goto out; |
| 404 | |
| 405 | pcache = kmalloc(sizeof(struct pid_cache), GFP_KERNEL); |
| 406 | if (pcache == NULL) |
| 407 | goto err_alloc; |
| 408 | |
| 409 | snprintf(pcache->name, sizeof(pcache->name), "pid_%d", nr_ids); |
| 410 | cachep = kmem_cache_create(pcache->name, |
| 411 | /* FIXME add numerical ids here */ |
| 412 | sizeof(struct pid), 0, SLAB_HWCACHE_ALIGN, NULL); |
| 413 | if (cachep == NULL) |
| 414 | goto err_cachep; |
| 415 | |
| 416 | pcache->nr_ids = nr_ids; |
| 417 | pcache->cachep = cachep; |
| 418 | list_add(&pcache->list, &pid_caches_lh); |
| 419 | out: |
| 420 | mutex_unlock(&pid_caches_mutex); |
| 421 | return pcache->cachep; |
| 422 | |
| 423 | err_cachep: |
| 424 | kfree(pcache); |
| 425 | err_alloc: |
| 426 | mutex_unlock(&pid_caches_mutex); |
| 427 | return NULL; |
| 428 | } |
| 429 | |
Eric W. Biederman | 213dd26 | 2007-07-15 23:41:15 -0700 | [diff] [blame] | 430 | struct pid_namespace *copy_pid_ns(unsigned long flags, struct pid_namespace *old_ns) |
Cedric Le Goater | 9a575a9 | 2006-12-08 02:37:59 -0800 | [diff] [blame] | 431 | { |
Badari Pulavarty | e3222c4 | 2007-05-08 00:25:21 -0700 | [diff] [blame] | 432 | BUG_ON(!old_ns); |
Cedric Le Goater | 9a575a9 | 2006-12-08 02:37:59 -0800 | [diff] [blame] | 433 | get_pid_ns(old_ns); |
Badari Pulavarty | e3222c4 | 2007-05-08 00:25:21 -0700 | [diff] [blame] | 434 | return old_ns; |
Cedric Le Goater | 9a575a9 | 2006-12-08 02:37:59 -0800 | [diff] [blame] | 435 | } |
| 436 | |
| 437 | void free_pid_ns(struct kref *kref) |
| 438 | { |
| 439 | struct pid_namespace *ns; |
| 440 | |
| 441 | ns = container_of(kref, struct pid_namespace, kref); |
| 442 | kfree(ns); |
| 443 | } |
| 444 | |
Eric W. Biederman | 0804ef4 | 2006-10-02 02:17:04 -0700 | [diff] [blame] | 445 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 446 | * The pid hash table is scaled according to the amount of memory in the |
| 447 | * machine. From a minimum of 16 slots up to 4096 slots at one gigabyte or |
| 448 | * more. |
| 449 | */ |
| 450 | void __init pidhash_init(void) |
| 451 | { |
Eric W. Biederman | 92476d7 | 2006-03-31 02:31:42 -0800 | [diff] [blame] | 452 | int i, pidhash_size; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 453 | unsigned long megabytes = nr_kernel_pages >> (20 - PAGE_SHIFT); |
| 454 | |
| 455 | pidhash_shift = max(4, fls(megabytes * 4)); |
| 456 | pidhash_shift = min(12, pidhash_shift); |
| 457 | pidhash_size = 1 << pidhash_shift; |
| 458 | |
| 459 | printk("PID hash table entries: %d (order: %d, %Zd bytes)\n", |
| 460 | pidhash_size, pidhash_shift, |
Eric W. Biederman | 92476d7 | 2006-03-31 02:31:42 -0800 | [diff] [blame] | 461 | pidhash_size * sizeof(struct hlist_head)); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 462 | |
Eric W. Biederman | 92476d7 | 2006-03-31 02:31:42 -0800 | [diff] [blame] | 463 | pid_hash = alloc_bootmem(pidhash_size * sizeof(*(pid_hash))); |
| 464 | if (!pid_hash) |
| 465 | panic("Could not alloc pidhash!\n"); |
| 466 | for (i = 0; i < pidhash_size; i++) |
| 467 | INIT_HLIST_HEAD(&pid_hash[i]); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 468 | } |
| 469 | |
| 470 | void __init pidmap_init(void) |
| 471 | { |
Sukadev Bhattiprolu | 61a58c6 | 2006-12-08 02:37:58 -0800 | [diff] [blame] | 472 | init_pid_ns.pidmap[0].page = kzalloc(PAGE_SIZE, GFP_KERNEL); |
Oleg Nesterov | 73b9ebf | 2006-03-28 16:11:07 -0800 | [diff] [blame] | 473 | /* Reserve PID 0. We never call free_pidmap(0) */ |
Sukadev Bhattiprolu | 61a58c6 | 2006-12-08 02:37:58 -0800 | [diff] [blame] | 474 | set_bit(0, init_pid_ns.pidmap[0].page); |
| 475 | atomic_dec(&init_pid_ns.pidmap[0].nr_free); |
Eric W. Biederman | 92476d7 | 2006-03-31 02:31:42 -0800 | [diff] [blame] | 476 | |
Pavel Emelianov | baf8f0f | 2007-10-18 23:39:48 -0700 | [diff] [blame] | 477 | init_pid_ns.pid_cachep = create_pid_cachep(1); |
| 478 | if (init_pid_ns.pid_cachep == NULL) |
| 479 | panic("Can't create pid_1 cachep\n"); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 480 | } |