blob: 79d0d4953cada643890cb6fd62323fa07a9dede5 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * This file contains the procedures for the handling of select and poll
3 *
4 * Created for Linux based loosely upon Mathius Lattner's minix
5 * patches by Peter MacDonald. Heavily edited by Linus.
6 *
7 * 4 February 1994
8 * COFF/ELF binary emulation. If the process has the STICKY_TIMEOUTS
9 * flag set in its personality we do *not* modify the given timeout
10 * parameter to reflect time remaining.
11 *
12 * 24 January 2000
13 * Changed sys_poll()/do_poll() to use PAGE_SIZE chunk-based allocation
14 * of fds to overcome nfds < 16390 descriptors limit (Tigran Aivazian).
15 */
16
Milind Arun Choudhary022a1692007-05-08 00:29:02 -070017#include <linux/kernel.h>
Alexey Dobriyana99bbaf2009-10-04 16:11:37 +040018#include <linux/sched.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070019#include <linux/syscalls.h>
Paul Gortmaker630d9c42011-11-16 23:57:37 -050020#include <linux/export.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070021#include <linux/slab.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070022#include <linux/poll.h>
23#include <linux/personality.h> /* for STICKY_TIMEOUTS */
24#include <linux/file.h>
Al Viro9f3acc32008-04-24 07:44:08 -040025#include <linux/fdtable.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070026#include <linux/fs.h>
Dipankar Sarmab8359962005-09-09 13:04:14 -070027#include <linux/rcupdate.h>
Arjan van de Ven8ff3e8e2008-08-31 08:26:40 -070028#include <linux/hrtimer.h>
Clark Williams8bd75c72013-02-07 09:47:07 -060029#include <linux/sched/rt.h>
Colin Cross9745cdb2013-05-06 23:50:17 +000030#include <linux/freezer.h>
Eliezer Tamir076bb0c2013-07-10 17:13:17 +030031#include <net/busy_poll.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070032
33#include <asm/uaccess.h>
34
Arjan van de Ven90d6e242008-09-01 15:55:35 -070035
36/*
37 * Estimate expected accuracy in ns from a timeval.
38 *
39 * After quite a bit of churning around, we've settled on
40 * a simple thing of taking 0.1% of the timeout as the
41 * slack, with a cap of 100 msec.
42 * "nice" tasks get a 0.5% slack instead.
43 *
44 * Consider this comment an open invitation to come up with even
45 * better solutions..
46 */
47
Guillaume Knispel5ae87e72009-09-22 16:43:30 -070048#define MAX_SLACK (100 * NSEC_PER_MSEC)
49
Arjan van de Ven96d2ab42008-09-07 16:08:55 -070050static long __estimate_accuracy(struct timespec *tv)
Arjan van de Ven90d6e242008-09-01 15:55:35 -070051{
Arjan van de Ven96d2ab42008-09-07 16:08:55 -070052 long slack;
Arjan van de Ven90d6e242008-09-01 15:55:35 -070053 int divfactor = 1000;
54
Guillaume Knispel5ae87e72009-09-22 16:43:30 -070055 if (tv->tv_sec < 0)
56 return 0;
57
Arjan van de Ven4ce105d2008-09-07 15:31:39 -070058 if (task_nice(current) > 0)
Arjan van de Ven90d6e242008-09-01 15:55:35 -070059 divfactor = divfactor / 5;
60
Guillaume Knispel5ae87e72009-09-22 16:43:30 -070061 if (tv->tv_sec > MAX_SLACK / (NSEC_PER_SEC/divfactor))
62 return MAX_SLACK;
63
Arjan van de Ven90d6e242008-09-01 15:55:35 -070064 slack = tv->tv_nsec / divfactor;
65 slack += tv->tv_sec * (NSEC_PER_SEC/divfactor);
66
Guillaume Knispel5ae87e72009-09-22 16:43:30 -070067 if (slack > MAX_SLACK)
68 return MAX_SLACK;
Arjan van de Ven96d2ab42008-09-07 16:08:55 -070069
Arjan van de Ven90d6e242008-09-01 15:55:35 -070070 return slack;
71}
72
Shawn Bohrer95aac7b2010-10-27 15:34:54 -070073long select_estimate_accuracy(struct timespec *tv)
Arjan van de Ven90d6e242008-09-01 15:55:35 -070074{
75 unsigned long ret;
76 struct timespec now;
77
78 /*
79 * Realtime tasks get a slack of 0 for obvious reasons.
80 */
81
Arjan van de Ven4ce105d2008-09-07 15:31:39 -070082 if (rt_task(current))
Arjan van de Ven90d6e242008-09-01 15:55:35 -070083 return 0;
84
85 ktime_get_ts(&now);
86 now = timespec_sub(*tv, now);
87 ret = __estimate_accuracy(&now);
88 if (ret < current->timer_slack_ns)
89 return current->timer_slack_ns;
90 return ret;
91}
92
93
94
Linus Torvalds1da177e2005-04-16 15:20:36 -070095struct poll_table_page {
96 struct poll_table_page * next;
97 struct poll_table_entry * entry;
98 struct poll_table_entry entries[0];
99};
100
101#define POLL_TABLE_FULL(table) \
102 ((unsigned long)((table)->entry+1) > PAGE_SIZE + (unsigned long)(table))
103
104/*
105 * Ok, Peter made a complicated, but straightforward multiple_wait() function.
106 * I have rewritten this, taking some shortcuts: This code may not be easy to
107 * follow, but it should be free of race-conditions, and it's practical. If you
108 * understand what I'm doing here, then you understand how the linux
109 * sleep/wakeup mechanism works.
110 *
111 * Two very simple procedures, poll_wait() and poll_freewait() make all the
112 * work. poll_wait() is an inline-function defined in <linux/poll.h>,
113 * as all select/poll functions have to call it to add an entry to the
114 * poll table.
115 */
Adrian Bunk75c96f82005-05-05 16:16:09 -0700116static void __pollwait(struct file *filp, wait_queue_head_t *wait_address,
117 poll_table *p);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700118
119void poll_initwait(struct poll_wqueues *pwq)
120{
121 init_poll_funcptr(&pwq->pt, __pollwait);
Tejun Heo5f820f62009-01-06 14:40:59 -0800122 pwq->polling_task = current;
Guillaume Knispelb2add732009-08-15 19:30:24 +0200123 pwq->triggered = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700124 pwq->error = 0;
125 pwq->table = NULL;
Andi Kleen70674f92006-03-28 01:56:33 -0800126 pwq->inline_index = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700127}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700128EXPORT_SYMBOL(poll_initwait);
129
Andi Kleen70674f92006-03-28 01:56:33 -0800130static void free_poll_entry(struct poll_table_entry *entry)
131{
WANG Congccf67802007-05-09 07:10:02 +0200132 remove_wait_queue(entry->wait_address, &entry->wait);
Andi Kleen70674f92006-03-28 01:56:33 -0800133 fput(entry->filp);
134}
135
Linus Torvalds1da177e2005-04-16 15:20:36 -0700136void poll_freewait(struct poll_wqueues *pwq)
137{
138 struct poll_table_page * p = pwq->table;
Andi Kleen70674f92006-03-28 01:56:33 -0800139 int i;
140 for (i = 0; i < pwq->inline_index; i++)
141 free_poll_entry(pwq->inline_entries + i);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700142 while (p) {
143 struct poll_table_entry * entry;
144 struct poll_table_page *old;
145
146 entry = p->entry;
147 do {
148 entry--;
Andi Kleen70674f92006-03-28 01:56:33 -0800149 free_poll_entry(entry);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700150 } while (entry > p->entries);
151 old = p;
152 p = p->next;
153 free_page((unsigned long) old);
154 }
155}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700156EXPORT_SYMBOL(poll_freewait);
157
Tejun Heo5f820f62009-01-06 14:40:59 -0800158static struct poll_table_entry *poll_get_entry(struct poll_wqueues *p)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700159{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700160 struct poll_table_page *table = p->table;
161
Andi Kleen70674f92006-03-28 01:56:33 -0800162 if (p->inline_index < N_INLINE_POLL_ENTRIES)
163 return p->inline_entries + p->inline_index++;
164
Linus Torvalds1da177e2005-04-16 15:20:36 -0700165 if (!table || POLL_TABLE_FULL(table)) {
166 struct poll_table_page *new_table;
167
168 new_table = (struct poll_table_page *) __get_free_page(GFP_KERNEL);
169 if (!new_table) {
170 p->error = -ENOMEM;
Andi Kleen70674f92006-03-28 01:56:33 -0800171 return NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700172 }
173 new_table->entry = new_table->entries;
174 new_table->next = table;
175 p->table = new_table;
176 table = new_table;
177 }
178
Andi Kleen70674f92006-03-28 01:56:33 -0800179 return table->entry++;
180}
181
Eric Dumazet4938d7e2009-06-16 15:33:36 -0700182static int __pollwake(wait_queue_t *wait, unsigned mode, int sync, void *key)
Tejun Heo5f820f62009-01-06 14:40:59 -0800183{
184 struct poll_wqueues *pwq = wait->private;
185 DECLARE_WAITQUEUE(dummy_wait, pwq->polling_task);
186
187 /*
188 * Although this function is called under waitqueue lock, LOCK
189 * doesn't imply write barrier and the users expect write
190 * barrier semantics on wakeup functions. The following
191 * smp_wmb() is equivalent to smp_wmb() in try_to_wake_up()
Peter Zijlstrab92b8b32015-05-12 10:51:55 +0200192 * and is paired with smp_store_mb() in poll_schedule_timeout.
Tejun Heo5f820f62009-01-06 14:40:59 -0800193 */
194 smp_wmb();
195 pwq->triggered = 1;
196
197 /*
198 * Perform the default wake up operation using a dummy
199 * waitqueue.
200 *
201 * TODO: This is hacky but there currently is no interface to
202 * pass in @sync. @sync is scheduled to be removed and once
203 * that happens, wake_up_process() can be used directly.
204 */
205 return default_wake_function(&dummy_wait, mode, sync, key);
206}
207
Eric Dumazet4938d7e2009-06-16 15:33:36 -0700208static int pollwake(wait_queue_t *wait, unsigned mode, int sync, void *key)
209{
210 struct poll_table_entry *entry;
211
212 entry = container_of(wait, struct poll_table_entry, wait);
213 if (key && !((unsigned long)key & entry->key))
214 return 0;
215 return __pollwake(wait, mode, sync, key);
216}
217
Andi Kleen70674f92006-03-28 01:56:33 -0800218/* Add a new entry */
219static void __pollwait(struct file *filp, wait_queue_head_t *wait_address,
220 poll_table *p)
221{
Tejun Heo5f820f62009-01-06 14:40:59 -0800222 struct poll_wqueues *pwq = container_of(p, struct poll_wqueues, pt);
223 struct poll_table_entry *entry = poll_get_entry(pwq);
Andi Kleen70674f92006-03-28 01:56:33 -0800224 if (!entry)
225 return;
Al Virocb0942b2012-08-27 14:48:26 -0400226 entry->filp = get_file(filp);
Andi Kleen70674f92006-03-28 01:56:33 -0800227 entry->wait_address = wait_address;
Hans Verkuil626cf232012-03-23 15:02:27 -0700228 entry->key = p->_key;
Tejun Heo5f820f62009-01-06 14:40:59 -0800229 init_waitqueue_func_entry(&entry->wait, pollwake);
230 entry->wait.private = pwq;
WANG Congccf67802007-05-09 07:10:02 +0200231 add_wait_queue(wait_address, &entry->wait);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700232}
233
Tejun Heo5f820f62009-01-06 14:40:59 -0800234int poll_schedule_timeout(struct poll_wqueues *pwq, int state,
235 ktime_t *expires, unsigned long slack)
236{
237 int rc = -EINTR;
238
239 set_current_state(state);
240 if (!pwq->triggered)
Rafael J. Wysocki59612d12013-10-29 23:43:08 +0100241 rc = schedule_hrtimeout_range(expires, slack, HRTIMER_MODE_ABS);
Tejun Heo5f820f62009-01-06 14:40:59 -0800242 __set_current_state(TASK_RUNNING);
243
244 /*
245 * Prepare for the next iteration.
246 *
Peter Zijlstrab92b8b32015-05-12 10:51:55 +0200247 * The following smp_store_mb() serves two purposes. First, it's
Tejun Heo5f820f62009-01-06 14:40:59 -0800248 * the counterpart rmb of the wmb in pollwake() such that data
249 * written before wake up is always visible after wake up.
250 * Second, the full barrier guarantees that triggered clearing
251 * doesn't pass event check of the next iteration. Note that
252 * this problem doesn't exist for the first iteration as
253 * add_wait_queue() has full barrier semantics.
254 */
Peter Zijlstrab92b8b32015-05-12 10:51:55 +0200255 smp_store_mb(pwq->triggered, 0);
Tejun Heo5f820f62009-01-06 14:40:59 -0800256
257 return rc;
258}
259EXPORT_SYMBOL(poll_schedule_timeout);
260
Thomas Gleixnerb773ad42008-08-31 08:16:57 -0700261/**
262 * poll_select_set_timeout - helper function to setup the timeout value
263 * @to: pointer to timespec variable for the final timeout
264 * @sec: seconds (from user space)
265 * @nsec: nanoseconds (from user space)
266 *
267 * Note, we do not use a timespec for the user space value here, That
268 * way we can use the function for timeval and compat interfaces as well.
269 *
270 * Returns -EINVAL if sec/nsec are not normalized. Otherwise 0.
271 */
272int poll_select_set_timeout(struct timespec *to, long sec, long nsec)
273{
274 struct timespec ts = {.tv_sec = sec, .tv_nsec = nsec};
275
276 if (!timespec_valid(&ts))
277 return -EINVAL;
278
279 /* Optimize for the zero timeout value here */
280 if (!sec && !nsec) {
281 to->tv_sec = to->tv_nsec = 0;
282 } else {
283 ktime_get_ts(to);
284 *to = timespec_add_safe(*to, ts);
285 }
286 return 0;
287}
288
289static int poll_select_copy_remaining(struct timespec *end_time, void __user *p,
290 int timeval, int ret)
291{
292 struct timespec rts;
293 struct timeval rtv;
294
295 if (!p)
296 return ret;
297
298 if (current->personality & STICKY_TIMEOUTS)
299 goto sticky;
300
301 /* No update for zero timeout */
302 if (!end_time->tv_sec && !end_time->tv_nsec)
303 return ret;
304
305 ktime_get_ts(&rts);
306 rts = timespec_sub(*end_time, rts);
307 if (rts.tv_sec < 0)
308 rts.tv_sec = rts.tv_nsec = 0;
309
310 if (timeval) {
Vasiliy Kulikov65329bf2011-01-12 17:00:00 -0800311 if (sizeof(rtv) > sizeof(rtv.tv_sec) + sizeof(rtv.tv_usec))
312 memset(&rtv, 0, sizeof(rtv));
Thomas Gleixnerb773ad42008-08-31 08:16:57 -0700313 rtv.tv_sec = rts.tv_sec;
314 rtv.tv_usec = rts.tv_nsec / NSEC_PER_USEC;
315
316 if (!copy_to_user(p, &rtv, sizeof(rtv)))
317 return ret;
318
319 } else if (!copy_to_user(p, &rts, sizeof(rts)))
320 return ret;
321
322 /*
323 * If an application puts its timeval in read-only memory, we
324 * don't want the Linux-specific update to the timeval to
325 * cause a fault after the select has completed
326 * successfully. However, because we're not updating the
327 * timeval, we can't restart the system call.
328 */
329
330sticky:
331 if (ret == -ERESTARTNOHAND)
332 ret = -EINTR;
333 return ret;
334}
335
Linus Torvalds1da177e2005-04-16 15:20:36 -0700336#define FDS_IN(fds, n) (fds->in + n)
337#define FDS_OUT(fds, n) (fds->out + n)
338#define FDS_EX(fds, n) (fds->ex + n)
339
340#define BITS(fds, n) (*FDS_IN(fds, n)|*FDS_OUT(fds, n)|*FDS_EX(fds, n))
341
342static int max_select_fd(unsigned long n, fd_set_bits *fds)
343{
344 unsigned long *open_fds;
345 unsigned long set;
346 int max;
Dipankar Sarmabadf1662005-09-09 13:04:10 -0700347 struct fdtable *fdt;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700348
349 /* handle last in-complete long-word first */
Josh Boyer8ded2bb2012-07-25 10:40:34 -0400350 set = ~(~0UL << (n & (BITS_PER_LONG-1)));
351 n /= BITS_PER_LONG;
Dipankar Sarmabadf1662005-09-09 13:04:10 -0700352 fdt = files_fdtable(current->files);
David Howells1fd36ad2012-02-16 17:49:54 +0000353 open_fds = fdt->open_fds + n;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700354 max = 0;
355 if (set) {
356 set &= BITS(fds, n);
357 if (set) {
358 if (!(set & ~*open_fds))
359 goto get_max;
360 return -EBADF;
361 }
362 }
363 while (n) {
364 open_fds--;
365 n--;
366 set = BITS(fds, n);
367 if (!set)
368 continue;
369 if (set & ~*open_fds)
370 return -EBADF;
371 if (max)
372 continue;
373get_max:
374 do {
375 max++;
376 set >>= 1;
377 } while (set);
Josh Boyer8ded2bb2012-07-25 10:40:34 -0400378 max += n * BITS_PER_LONG;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700379 }
380
381 return max;
382}
383
Linus Torvalds1da177e2005-04-16 15:20:36 -0700384#define POLLIN_SET (POLLRDNORM | POLLRDBAND | POLLIN | POLLHUP | POLLERR)
385#define POLLOUT_SET (POLLWRBAND | POLLWRNORM | POLLOUT | POLLERR)
386#define POLLEX_SET (POLLPRI)
387
Eric Dumazet4938d7e2009-06-16 15:33:36 -0700388static inline void wait_key_set(poll_table *wait, unsigned long in,
Eliezer Tamir2d48d672013-06-24 10:28:03 +0300389 unsigned long out, unsigned long bit,
390 unsigned int ll_flag)
Eric Dumazet4938d7e2009-06-16 15:33:36 -0700391{
Eliezer Tamir2d48d672013-06-24 10:28:03 +0300392 wait->_key = POLLEX_SET | ll_flag;
Hans Verkuil626cf232012-03-23 15:02:27 -0700393 if (in & bit)
394 wait->_key |= POLLIN_SET;
395 if (out & bit)
396 wait->_key |= POLLOUT_SET;
Eric Dumazet4938d7e2009-06-16 15:33:36 -0700397}
398
Arjan van de Ven8ff3e8e2008-08-31 08:26:40 -0700399int do_select(int n, fd_set_bits *fds, struct timespec *end_time)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700400{
Arjan van de Ven8ff3e8e2008-08-31 08:26:40 -0700401 ktime_t expire, *to = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700402 struct poll_wqueues table;
403 poll_table *wait;
Arjan van de Ven8ff3e8e2008-08-31 08:26:40 -0700404 int retval, i, timed_out = 0;
Arjan van de Ven90d6e242008-09-01 15:55:35 -0700405 unsigned long slack = 0;
Eliezer Tamircbf55002013-07-08 16:20:34 +0300406 unsigned int busy_flag = net_busy_loop_on() ? POLL_BUSY_LOOP : 0;
Eliezer Tamir76b1e9b2013-07-09 13:09:21 +0300407 unsigned long busy_end = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700408
Dipankar Sarmab8359962005-09-09 13:04:14 -0700409 rcu_read_lock();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700410 retval = max_select_fd(n, fds);
Dipankar Sarmab8359962005-09-09 13:04:14 -0700411 rcu_read_unlock();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700412
413 if (retval < 0)
414 return retval;
415 n = retval;
416
417 poll_initwait(&table);
418 wait = &table.pt;
Arjan van de Ven8ff3e8e2008-08-31 08:26:40 -0700419 if (end_time && !end_time->tv_sec && !end_time->tv_nsec) {
Hans Verkuil626cf232012-03-23 15:02:27 -0700420 wait->_qproc = NULL;
Arjan van de Ven8ff3e8e2008-08-31 08:26:40 -0700421 timed_out = 1;
422 }
423
Arjan van de Ven96d2ab42008-09-07 16:08:55 -0700424 if (end_time && !timed_out)
Andrew Morton231f3d32010-10-27 15:34:53 -0700425 slack = select_estimate_accuracy(end_time);
Arjan van de Ven90d6e242008-09-01 15:55:35 -0700426
Linus Torvalds1da177e2005-04-16 15:20:36 -0700427 retval = 0;
428 for (;;) {
429 unsigned long *rinp, *routp, *rexp, *inp, *outp, *exp;
Eliezer Tamircbf55002013-07-08 16:20:34 +0300430 bool can_busy_loop = false;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700431
Linus Torvalds1da177e2005-04-16 15:20:36 -0700432 inp = fds->in; outp = fds->out; exp = fds->ex;
433 rinp = fds->res_in; routp = fds->res_out; rexp = fds->res_ex;
434
435 for (i = 0; i < n; ++rinp, ++routp, ++rexp) {
436 unsigned long in, out, ex, all_bits, bit = 1, mask, j;
437 unsigned long res_in = 0, res_out = 0, res_ex = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700438
439 in = *inp++; out = *outp++; ex = *exp++;
440 all_bits = in | out | ex;
441 if (all_bits == 0) {
Josh Boyer8ded2bb2012-07-25 10:40:34 -0400442 i += BITS_PER_LONG;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700443 continue;
444 }
445
Josh Boyer8ded2bb2012-07-25 10:40:34 -0400446 for (j = 0; j < BITS_PER_LONG; ++j, ++i, bit <<= 1) {
Al Viro2903ff02012-08-28 12:52:22 -0400447 struct fd f;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700448 if (i >= n)
449 break;
450 if (!(bit & all_bits))
451 continue;
Al Viro2903ff02012-08-28 12:52:22 -0400452 f = fdget(i);
453 if (f.file) {
454 const struct file_operations *f_op;
455 f_op = f.file->f_op;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700456 mask = DEFAULT_POLLMASK;
Al Viro72c2d532013-09-22 16:27:52 -0400457 if (f_op->poll) {
Eliezer Tamir2d48d672013-06-24 10:28:03 +0300458 wait_key_set(wait, in, out,
Eliezer Tamircbf55002013-07-08 16:20:34 +0300459 bit, busy_flag);
Al Viro2903ff02012-08-28 12:52:22 -0400460 mask = (*f_op->poll)(f.file, wait);
Eric Dumazet4938d7e2009-06-16 15:33:36 -0700461 }
Al Viro2903ff02012-08-28 12:52:22 -0400462 fdput(f);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700463 if ((mask & POLLIN_SET) && (in & bit)) {
464 res_in |= bit;
465 retval++;
Hans Verkuil626cf232012-03-23 15:02:27 -0700466 wait->_qproc = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700467 }
468 if ((mask & POLLOUT_SET) && (out & bit)) {
469 res_out |= bit;
470 retval++;
Hans Verkuil626cf232012-03-23 15:02:27 -0700471 wait->_qproc = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700472 }
473 if ((mask & POLLEX_SET) && (ex & bit)) {
474 res_ex |= bit;
475 retval++;
Hans Verkuil626cf232012-03-23 15:02:27 -0700476 wait->_qproc = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700477 }
Eliezer Tamir2d48d672013-06-24 10:28:03 +0300478 /* got something, stop busy polling */
Eliezer Tamircbf55002013-07-08 16:20:34 +0300479 if (retval) {
480 can_busy_loop = false;
481 busy_flag = 0;
482
483 /*
484 * only remember a returned
485 * POLL_BUSY_LOOP if we asked for it
486 */
487 } else if (busy_flag & mask)
488 can_busy_loop = true;
489
Linus Torvalds1da177e2005-04-16 15:20:36 -0700490 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700491 }
492 if (res_in)
493 *rinp = res_in;
494 if (res_out)
495 *routp = res_out;
496 if (res_ex)
497 *rexp = res_ex;
Linus Torvalds55d85382008-06-22 12:23:15 -0700498 cond_resched();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700499 }
Hans Verkuil626cf232012-03-23 15:02:27 -0700500 wait->_qproc = NULL;
Arjan van de Ven8ff3e8e2008-08-31 08:26:40 -0700501 if (retval || timed_out || signal_pending(current))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700502 break;
Pavel Machekf5264482008-04-21 22:15:06 +0000503 if (table.error) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700504 retval = table.error;
505 break;
506 }
David Woodhouse9f729492006-01-18 17:44:05 -0800507
Eliezer Tamircbf55002013-07-08 16:20:34 +0300508 /* only if found POLL_BUSY_LOOP sockets && not out of time */
Eliezer Tamir76b1e9b2013-07-09 13:09:21 +0300509 if (can_busy_loop && !need_resched()) {
510 if (!busy_end) {
511 busy_end = busy_loop_end_time();
512 continue;
513 }
514 if (!busy_loop_timeout(busy_end))
515 continue;
516 }
517 busy_flag = 0;
Eliezer Tamir2d48d672013-06-24 10:28:03 +0300518
Arjan van de Ven8ff3e8e2008-08-31 08:26:40 -0700519 /*
520 * If this is the first loop and we have a timeout
521 * given, then we convert to ktime_t and set the to
522 * pointer to the expiry value.
523 */
524 if (end_time && !to) {
525 expire = timespec_to_ktime(*end_time);
526 to = &expire;
David Woodhouse9f729492006-01-18 17:44:05 -0800527 }
Arjan van de Ven8ff3e8e2008-08-31 08:26:40 -0700528
Tejun Heo5f820f62009-01-06 14:40:59 -0800529 if (!poll_schedule_timeout(&table, TASK_INTERRUPTIBLE,
530 to, slack))
Arjan van de Ven8ff3e8e2008-08-31 08:26:40 -0700531 timed_out = 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700532 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700533
534 poll_freewait(&table);
535
Linus Torvalds1da177e2005-04-16 15:20:36 -0700536 return retval;
537}
538
Linus Torvalds1da177e2005-04-16 15:20:36 -0700539/*
540 * We can actually return ERESTARTSYS instead of EINTR, but I'd
541 * like to be certain this leads to no problems. So I return
542 * EINTR just for safety.
543 *
544 * Update: ERESTARTSYS breaks at least the xview clock binary, so
545 * I'm trying ERESTARTNOHAND which restart only when you want to.
546 */
Al Viroa2dcb442008-04-23 14:05:15 -0400547int core_sys_select(int n, fd_set __user *inp, fd_set __user *outp,
Arjan van de Ven8ff3e8e2008-08-31 08:26:40 -0700548 fd_set __user *exp, struct timespec *end_time)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700549{
550 fd_set_bits fds;
Andrew Morton29ff2db2006-04-10 22:52:46 -0700551 void *bits;
Vadim Lobanovbbea9f62006-12-10 02:21:12 -0800552 int ret, max_fds;
Mitchell Blank Jrb04eb6a2006-04-10 22:54:08 -0700553 unsigned int size;
Dipankar Sarmabadf1662005-09-09 13:04:10 -0700554 struct fdtable *fdt;
Andi Kleen70674f92006-03-28 01:56:33 -0800555 /* Allocate small arguments on the stack to save memory and be faster */
Jes Sorensen30c14e42006-03-31 11:18:57 -0500556 long stack_fds[SELECT_STACK_ALLOC/sizeof(long)];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700557
Linus Torvalds1da177e2005-04-16 15:20:36 -0700558 ret = -EINVAL;
559 if (n < 0)
560 goto out_nofds;
561
Vadim Lobanovbbea9f62006-12-10 02:21:12 -0800562 /* max_fds can increase, so grab it once to avoid race */
Dipankar Sarmab8359962005-09-09 13:04:14 -0700563 rcu_read_lock();
Dipankar Sarmabadf1662005-09-09 13:04:10 -0700564 fdt = files_fdtable(current->files);
Vadim Lobanovbbea9f62006-12-10 02:21:12 -0800565 max_fds = fdt->max_fds;
Dipankar Sarmab8359962005-09-09 13:04:14 -0700566 rcu_read_unlock();
Vadim Lobanovbbea9f62006-12-10 02:21:12 -0800567 if (n > max_fds)
568 n = max_fds;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700569
570 /*
571 * We need 6 bitmaps (in/out/ex for both incoming and outgoing),
572 * since we used fdset we need to allocate memory in units of
573 * long-words.
574 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700575 size = FDS_BYTES(n);
Mitchell Blank Jrb04eb6a2006-04-10 22:54:08 -0700576 bits = stack_fds;
577 if (size > sizeof(stack_fds) / 6) {
578 /* Not enough space in on-stack array; must use kmalloc */
579 ret = -ENOMEM;
Andi Kleen70674f92006-03-28 01:56:33 -0800580 bits = kmalloc(6 * size, GFP_KERNEL);
Mitchell Blank Jrb04eb6a2006-04-10 22:54:08 -0700581 if (!bits)
582 goto out_nofds;
583 }
Andrew Morton29ff2db2006-04-10 22:52:46 -0700584 fds.in = bits;
585 fds.out = bits + size;
586 fds.ex = bits + 2*size;
587 fds.res_in = bits + 3*size;
588 fds.res_out = bits + 4*size;
589 fds.res_ex = bits + 5*size;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700590
591 if ((ret = get_fd_set(n, inp, fds.in)) ||
592 (ret = get_fd_set(n, outp, fds.out)) ||
593 (ret = get_fd_set(n, exp, fds.ex)))
594 goto out;
595 zero_fd_set(n, fds.res_in);
596 zero_fd_set(n, fds.res_out);
597 zero_fd_set(n, fds.res_ex);
598
Arjan van de Ven8ff3e8e2008-08-31 08:26:40 -0700599 ret = do_select(n, &fds, end_time);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700600
601 if (ret < 0)
602 goto out;
603 if (!ret) {
604 ret = -ERESTARTNOHAND;
605 if (signal_pending(current))
606 goto out;
607 ret = 0;
608 }
609
610 if (set_fd_set(n, inp, fds.res_in) ||
611 set_fd_set(n, outp, fds.res_out) ||
612 set_fd_set(n, exp, fds.res_ex))
613 ret = -EFAULT;
614
615out:
Andi Kleen70674f92006-03-28 01:56:33 -0800616 if (bits != stack_fds)
617 kfree(bits);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700618out_nofds:
619 return ret;
620}
621
Heiko Carstens5a8a82b2009-01-14 14:14:25 +0100622SYSCALL_DEFINE5(select, int, n, fd_set __user *, inp, fd_set __user *, outp,
623 fd_set __user *, exp, struct timeval __user *, tvp)
David Woodhouse9f729492006-01-18 17:44:05 -0800624{
Arjan van de Ven8ff3e8e2008-08-31 08:26:40 -0700625 struct timespec end_time, *to = NULL;
David Woodhouse9f729492006-01-18 17:44:05 -0800626 struct timeval tv;
627 int ret;
628
629 if (tvp) {
630 if (copy_from_user(&tv, tvp, sizeof(tv)))
631 return -EFAULT;
632
Arjan van de Ven8ff3e8e2008-08-31 08:26:40 -0700633 to = &end_time;
Arjan van de Ven4d36a9e2008-10-25 12:41:41 -0700634 if (poll_select_set_timeout(to,
635 tv.tv_sec + (tv.tv_usec / USEC_PER_SEC),
636 (tv.tv_usec % USEC_PER_SEC) * NSEC_PER_USEC))
David Woodhouse9f729492006-01-18 17:44:05 -0800637 return -EINVAL;
David Woodhouse9f729492006-01-18 17:44:05 -0800638 }
639
Arjan van de Ven8ff3e8e2008-08-31 08:26:40 -0700640 ret = core_sys_select(n, inp, outp, exp, to);
641 ret = poll_select_copy_remaining(&end_time, tvp, 1, ret);
David Woodhouse9f729492006-01-18 17:44:05 -0800642
643 return ret;
644}
645
Heiko Carstensc9da9f22009-01-14 14:13:57 +0100646static long do_pselect(int n, fd_set __user *inp, fd_set __user *outp,
647 fd_set __user *exp, struct timespec __user *tsp,
648 const sigset_t __user *sigmask, size_t sigsetsize)
David Woodhouse9f729492006-01-18 17:44:05 -0800649{
David Woodhouse9f729492006-01-18 17:44:05 -0800650 sigset_t ksigmask, sigsaved;
Arjan van de Ven8ff3e8e2008-08-31 08:26:40 -0700651 struct timespec ts, end_time, *to = NULL;
David Woodhouse9f729492006-01-18 17:44:05 -0800652 int ret;
653
654 if (tsp) {
655 if (copy_from_user(&ts, tsp, sizeof(ts)))
656 return -EFAULT;
657
Arjan van de Ven8ff3e8e2008-08-31 08:26:40 -0700658 to = &end_time;
659 if (poll_select_set_timeout(to, ts.tv_sec, ts.tv_nsec))
David Woodhouse9f729492006-01-18 17:44:05 -0800660 return -EINVAL;
David Woodhouse9f729492006-01-18 17:44:05 -0800661 }
662
663 if (sigmask) {
664 /* XXX: Don't preclude handling different sized sigset_t's. */
665 if (sigsetsize != sizeof(sigset_t))
666 return -EINVAL;
667 if (copy_from_user(&ksigmask, sigmask, sizeof(ksigmask)))
668 return -EFAULT;
669
670 sigdelsetmask(&ksigmask, sigmask(SIGKILL)|sigmask(SIGSTOP));
671 sigprocmask(SIG_SETMASK, &ksigmask, &sigsaved);
672 }
673
Bernd Schmidt62568512009-01-13 22:14:48 +0100674 ret = core_sys_select(n, inp, outp, exp, to);
Arjan van de Ven8ff3e8e2008-08-31 08:26:40 -0700675 ret = poll_select_copy_remaining(&end_time, tsp, 0, ret);
David Woodhouse9f729492006-01-18 17:44:05 -0800676
677 if (ret == -ERESTARTNOHAND) {
678 /*
679 * Don't restore the signal mask yet. Let do_signal() deliver
680 * the signal on the way back to userspace, before the signal
681 * mask is restored.
682 */
683 if (sigmask) {
684 memcpy(&current->saved_sigmask, &sigsaved,
685 sizeof(sigsaved));
Roland McGrath4e4c22c2008-04-30 00:53:06 -0700686 set_restore_sigmask();
David Woodhouse9f729492006-01-18 17:44:05 -0800687 }
688 } else if (sigmask)
689 sigprocmask(SIG_SETMASK, &sigsaved, NULL);
690
691 return ret;
692}
693
694/*
695 * Most architectures can't handle 7-argument syscalls. So we provide a
696 * 6-argument version where the sixth argument is a pointer to a structure
697 * which has a pointer to the sigset_t itself followed by a size_t containing
698 * the sigset size.
699 */
Heiko Carstensd4e82042009-01-14 14:14:34 +0100700SYSCALL_DEFINE6(pselect6, int, n, fd_set __user *, inp, fd_set __user *, outp,
701 fd_set __user *, exp, struct timespec __user *, tsp,
702 void __user *, sig)
David Woodhouse9f729492006-01-18 17:44:05 -0800703{
704 size_t sigsetsize = 0;
705 sigset_t __user *up = NULL;
706
707 if (sig) {
708 if (!access_ok(VERIFY_READ, sig, sizeof(void *)+sizeof(size_t))
Al Viroe110ab92006-02-01 05:26:09 -0500709 || __get_user(up, (sigset_t __user * __user *)sig)
David Woodhouse9f729492006-01-18 17:44:05 -0800710 || __get_user(sigsetsize,
Al Viroe110ab92006-02-01 05:26:09 -0500711 (size_t __user *)(sig+sizeof(void *))))
David Woodhouse9f729492006-01-18 17:44:05 -0800712 return -EFAULT;
713 }
714
Heiko Carstensc9da9f22009-01-14 14:13:57 +0100715 return do_pselect(n, inp, outp, exp, tsp, up, sigsetsize);
David Woodhouse9f729492006-01-18 17:44:05 -0800716}
David Woodhouse9f729492006-01-18 17:44:05 -0800717
Christoph Hellwig5d0e5282010-03-10 15:21:13 -0800718#ifdef __ARCH_WANT_SYS_OLD_SELECT
719struct sel_arg_struct {
720 unsigned long n;
721 fd_set __user *inp, *outp, *exp;
722 struct timeval __user *tvp;
723};
724
725SYSCALL_DEFINE1(old_select, struct sel_arg_struct __user *, arg)
726{
727 struct sel_arg_struct a;
728
729 if (copy_from_user(&a, arg, sizeof(a)))
730 return -EFAULT;
731 return sys_select(a.n, a.inp, a.outp, a.exp, a.tvp);
732}
733#endif
734
Linus Torvalds1da177e2005-04-16 15:20:36 -0700735struct poll_list {
736 struct poll_list *next;
737 int len;
738 struct pollfd entries[0];
739};
740
741#define POLLFD_PER_PAGE ((PAGE_SIZE-sizeof(struct poll_list)) / sizeof(struct pollfd))
742
Vadim Lobanov4a4b69f2006-06-23 02:05:16 -0700743/*
744 * Fish for pollable events on the pollfd->fd file descriptor. We're only
745 * interested in events matching the pollfd->events mask, and the result
746 * matching that mask is both recorded in pollfd->revents and returned. The
747 * pwait poll_table will be used by the fd-provided poll handler for waiting,
Hans Verkuil626cf232012-03-23 15:02:27 -0700748 * if pwait->_qproc is non-NULL.
Vadim Lobanov4a4b69f2006-06-23 02:05:16 -0700749 */
Eliezer Tamir2d48d672013-06-24 10:28:03 +0300750static inline unsigned int do_pollfd(struct pollfd *pollfd, poll_table *pwait,
Eliezer Tamircbf55002013-07-08 16:20:34 +0300751 bool *can_busy_poll,
752 unsigned int busy_flag)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700753{
Vadim Lobanov4a4b69f2006-06-23 02:05:16 -0700754 unsigned int mask;
755 int fd;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700756
Vadim Lobanov4a4b69f2006-06-23 02:05:16 -0700757 mask = 0;
758 fd = pollfd->fd;
759 if (fd >= 0) {
Al Viro2903ff02012-08-28 12:52:22 -0400760 struct fd f = fdget(fd);
Vadim Lobanov4a4b69f2006-06-23 02:05:16 -0700761 mask = POLLNVAL;
Al Viro2903ff02012-08-28 12:52:22 -0400762 if (f.file) {
Vadim Lobanov4a4b69f2006-06-23 02:05:16 -0700763 mask = DEFAULT_POLLMASK;
Al Viro72c2d532013-09-22 16:27:52 -0400764 if (f.file->f_op->poll) {
Hans Verkuil626cf232012-03-23 15:02:27 -0700765 pwait->_key = pollfd->events|POLLERR|POLLHUP;
Eliezer Tamircbf55002013-07-08 16:20:34 +0300766 pwait->_key |= busy_flag;
Al Viro2903ff02012-08-28 12:52:22 -0400767 mask = f.file->f_op->poll(f.file, pwait);
Eliezer Tamircbf55002013-07-08 16:20:34 +0300768 if (mask & busy_flag)
769 *can_busy_poll = true;
Eric Dumazet4938d7e2009-06-16 15:33:36 -0700770 }
Vadim Lobanov4a4b69f2006-06-23 02:05:16 -0700771 /* Mask out unneeded events. */
772 mask &= pollfd->events | POLLERR | POLLHUP;
Al Viro2903ff02012-08-28 12:52:22 -0400773 fdput(f);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700774 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700775 }
Vadim Lobanov4a4b69f2006-06-23 02:05:16 -0700776 pollfd->revents = mask;
777
778 return mask;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700779}
780
Mateusz Guzikccec5ee2016-01-06 06:41:53 +0100781static int do_poll(struct poll_list *list, struct poll_wqueues *wait,
782 struct timespec *end_time)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700783{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700784 poll_table* pt = &wait->pt;
Arjan van de Ven8ff3e8e2008-08-31 08:26:40 -0700785 ktime_t expire, *to = NULL;
786 int timed_out = 0, count = 0;
Arjan van de Ven90d6e242008-09-01 15:55:35 -0700787 unsigned long slack = 0;
Eliezer Tamircbf55002013-07-08 16:20:34 +0300788 unsigned int busy_flag = net_busy_loop_on() ? POLL_BUSY_LOOP : 0;
Eliezer Tamir76b1e9b2013-07-09 13:09:21 +0300789 unsigned long busy_end = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700790
David Woodhouse9f729492006-01-18 17:44:05 -0800791 /* Optimise the no-wait case */
Arjan van de Ven8ff3e8e2008-08-31 08:26:40 -0700792 if (end_time && !end_time->tv_sec && !end_time->tv_nsec) {
Hans Verkuil626cf232012-03-23 15:02:27 -0700793 pt->_qproc = NULL;
Arjan van de Ven8ff3e8e2008-08-31 08:26:40 -0700794 timed_out = 1;
795 }
Oleg Nesterov9bf084f2007-10-16 23:26:18 -0700796
Arjan van de Ven96d2ab42008-09-07 16:08:55 -0700797 if (end_time && !timed_out)
Andrew Morton231f3d32010-10-27 15:34:53 -0700798 slack = select_estimate_accuracy(end_time);
Arjan van de Ven90d6e242008-09-01 15:55:35 -0700799
Linus Torvalds1da177e2005-04-16 15:20:36 -0700800 for (;;) {
801 struct poll_list *walk;
Eliezer Tamircbf55002013-07-08 16:20:34 +0300802 bool can_busy_loop = false;
David Woodhouse9f729492006-01-18 17:44:05 -0800803
Vadim Lobanov4a4b69f2006-06-23 02:05:16 -0700804 for (walk = list; walk != NULL; walk = walk->next) {
805 struct pollfd * pfd, * pfd_end;
806
807 pfd = walk->entries;
808 pfd_end = pfd + walk->len;
809 for (; pfd != pfd_end; pfd++) {
810 /*
811 * Fish for events. If we found one, record it
Hans Verkuil626cf232012-03-23 15:02:27 -0700812 * and kill poll_table->_qproc, so we don't
Vadim Lobanov4a4b69f2006-06-23 02:05:16 -0700813 * needlessly register any other waiters after
814 * this. They'll get immediately deregistered
815 * when we break out and return.
816 */
Eliezer Tamircbf55002013-07-08 16:20:34 +0300817 if (do_pollfd(pfd, pt, &can_busy_loop,
818 busy_flag)) {
Vadim Lobanov4a4b69f2006-06-23 02:05:16 -0700819 count++;
Hans Verkuil626cf232012-03-23 15:02:27 -0700820 pt->_qproc = NULL;
Eliezer Tamircbf55002013-07-08 16:20:34 +0300821 /* found something, stop busy polling */
822 busy_flag = 0;
823 can_busy_loop = false;
Vadim Lobanov4a4b69f2006-06-23 02:05:16 -0700824 }
825 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700826 }
Vadim Lobanov4a4b69f2006-06-23 02:05:16 -0700827 /*
828 * All waiters have already been registered, so don't provide
Hans Verkuil626cf232012-03-23 15:02:27 -0700829 * a poll_table->_qproc to them on the next loop iteration.
Vadim Lobanov4a4b69f2006-06-23 02:05:16 -0700830 */
Hans Verkuil626cf232012-03-23 15:02:27 -0700831 pt->_qproc = NULL;
Oleg Nesterov9bf084f2007-10-16 23:26:18 -0700832 if (!count) {
833 count = wait->error;
834 if (signal_pending(current))
835 count = -EINTR;
836 }
Arjan van de Ven8ff3e8e2008-08-31 08:26:40 -0700837 if (count || timed_out)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700838 break;
David Woodhouse9f729492006-01-18 17:44:05 -0800839
Eliezer Tamircbf55002013-07-08 16:20:34 +0300840 /* only if found POLL_BUSY_LOOP sockets && not out of time */
Eliezer Tamir76b1e9b2013-07-09 13:09:21 +0300841 if (can_busy_loop && !need_resched()) {
842 if (!busy_end) {
843 busy_end = busy_loop_end_time();
844 continue;
845 }
846 if (!busy_loop_timeout(busy_end))
847 continue;
848 }
849 busy_flag = 0;
Eliezer Tamir91e2fd332013-06-28 15:59:35 +0300850
Arjan van de Ven8ff3e8e2008-08-31 08:26:40 -0700851 /*
852 * If this is the first loop and we have a timeout
853 * given, then we convert to ktime_t and set the to
854 * pointer to the expiry value.
855 */
856 if (end_time && !to) {
857 expire = timespec_to_ktime(*end_time);
858 to = &expire;
David Woodhouse9f729492006-01-18 17:44:05 -0800859 }
860
Tejun Heo5f820f62009-01-06 14:40:59 -0800861 if (!poll_schedule_timeout(wait, TASK_INTERRUPTIBLE, to, slack))
Arjan van de Ven8ff3e8e2008-08-31 08:26:40 -0700862 timed_out = 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700863 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700864 return count;
865}
866
Andi Kleen70674f92006-03-28 01:56:33 -0800867#define N_STACK_PPS ((sizeof(stack_pps) - sizeof(struct poll_list)) / \
868 sizeof(struct pollfd))
869
Arjan van de Ven8ff3e8e2008-08-31 08:26:40 -0700870int do_sys_poll(struct pollfd __user *ufds, unsigned int nfds,
871 struct timespec *end_time)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700872{
873 struct poll_wqueues table;
Oleg Nesterov252e5722007-10-16 23:26:17 -0700874 int err = -EFAULT, fdcount, len, size;
Jes Sorensen30c14e42006-03-31 11:18:57 -0500875 /* Allocate small arguments on the stack to save memory and be
876 faster - use long to make sure the buffer is aligned properly
877 on 64 bit archs to avoid unaligned access */
878 long stack_pps[POLL_STACK_ALLOC/sizeof(long)];
Oleg Nesterov252e5722007-10-16 23:26:17 -0700879 struct poll_list *const head = (struct poll_list *)stack_pps;
880 struct poll_list *walk = head;
881 unsigned long todo = nfds;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700882
Jiri Slabyd554ed892010-03-05 13:42:42 -0800883 if (nfds > rlimit(RLIMIT_NOFILE))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700884 return -EINVAL;
885
Oleg Nesterov252e5722007-10-16 23:26:17 -0700886 len = min_t(unsigned int, nfds, N_STACK_PPS);
887 for (;;) {
888 walk->next = NULL;
889 walk->len = len;
890 if (!len)
891 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700892
Oleg Nesterov252e5722007-10-16 23:26:17 -0700893 if (copy_from_user(walk->entries, ufds + nfds-todo,
894 sizeof(struct pollfd) * walk->len))
895 goto out_fds;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700896
Oleg Nesterov252e5722007-10-16 23:26:17 -0700897 todo -= walk->len;
898 if (!todo)
899 break;
900
901 len = min(todo, POLLFD_PER_PAGE);
902 size = sizeof(struct poll_list) + sizeof(struct pollfd) * len;
903 walk = walk->next = kmalloc(size, GFP_KERNEL);
904 if (!walk) {
905 err = -ENOMEM;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700906 goto out_fds;
907 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700908 }
David Woodhouse9f729492006-01-18 17:44:05 -0800909
Oleg Nesterov252e5722007-10-16 23:26:17 -0700910 poll_initwait(&table);
Mateusz Guzikccec5ee2016-01-06 06:41:53 +0100911 fdcount = do_poll(head, &table, end_time);
Oleg Nesterov252e5722007-10-16 23:26:17 -0700912 poll_freewait(&table);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700913
Oleg Nesterov252e5722007-10-16 23:26:17 -0700914 for (walk = head; walk; walk = walk->next) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700915 struct pollfd *fds = walk->entries;
916 int j;
917
Oleg Nesterov252e5722007-10-16 23:26:17 -0700918 for (j = 0; j < walk->len; j++, ufds++)
919 if (__put_user(fds[j].revents, &ufds->revents))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700920 goto out_fds;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700921 }
Oleg Nesterov252e5722007-10-16 23:26:17 -0700922
Linus Torvalds1da177e2005-04-16 15:20:36 -0700923 err = fdcount;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700924out_fds:
Oleg Nesterov252e5722007-10-16 23:26:17 -0700925 walk = head->next;
926 while (walk) {
927 struct poll_list *pos = walk;
928 walk = walk->next;
929 kfree(pos);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700930 }
Oleg Nesterov252e5722007-10-16 23:26:17 -0700931
Linus Torvalds1da177e2005-04-16 15:20:36 -0700932 return err;
933}
David Woodhouse9f729492006-01-18 17:44:05 -0800934
Chris Wright3075d9d2007-10-16 23:27:18 -0700935static long do_restart_poll(struct restart_block *restart_block)
936{
Arjan van de Ven8ff3e8e2008-08-31 08:26:40 -0700937 struct pollfd __user *ufds = restart_block->poll.ufds;
938 int nfds = restart_block->poll.nfds;
939 struct timespec *to = NULL, end_time;
Chris Wright3075d9d2007-10-16 23:27:18 -0700940 int ret;
941
Arjan van de Ven8ff3e8e2008-08-31 08:26:40 -0700942 if (restart_block->poll.has_timeout) {
943 end_time.tv_sec = restart_block->poll.tv_sec;
944 end_time.tv_nsec = restart_block->poll.tv_nsec;
945 to = &end_time;
946 }
947
948 ret = do_sys_poll(ufds, nfds, to);
949
Chris Wright3075d9d2007-10-16 23:27:18 -0700950 if (ret == -EINTR) {
951 restart_block->fn = do_restart_poll;
Chris Wright3075d9d2007-10-16 23:27:18 -0700952 ret = -ERESTART_RESTARTBLOCK;
953 }
954 return ret;
955}
956
Heiko Carstens5a8a82b2009-01-14 14:14:25 +0100957SYSCALL_DEFINE3(poll, struct pollfd __user *, ufds, unsigned int, nfds,
Linus Torvaldsfaf30902012-02-21 17:24:20 -0800958 int, timeout_msecs)
David Woodhouse9f729492006-01-18 17:44:05 -0800959{
Arjan van de Ven8ff3e8e2008-08-31 08:26:40 -0700960 struct timespec end_time, *to = NULL;
Chris Wright3075d9d2007-10-16 23:27:18 -0700961 int ret;
David Woodhouse9f729492006-01-18 17:44:05 -0800962
Arjan van de Ven8ff3e8e2008-08-31 08:26:40 -0700963 if (timeout_msecs >= 0) {
964 to = &end_time;
965 poll_select_set_timeout(to, timeout_msecs / MSEC_PER_SEC,
966 NSEC_PER_MSEC * (timeout_msecs % MSEC_PER_SEC));
David Woodhouse9f729492006-01-18 17:44:05 -0800967 }
968
Arjan van de Ven8ff3e8e2008-08-31 08:26:40 -0700969 ret = do_sys_poll(ufds, nfds, to);
970
Chris Wright3075d9d2007-10-16 23:27:18 -0700971 if (ret == -EINTR) {
972 struct restart_block *restart_block;
Arjan van de Ven8ff3e8e2008-08-31 08:26:40 -0700973
Andy Lutomirskif56141e2015-02-12 15:01:14 -0800974 restart_block = &current->restart_block;
Chris Wright3075d9d2007-10-16 23:27:18 -0700975 restart_block->fn = do_restart_poll;
Arjan van de Ven8ff3e8e2008-08-31 08:26:40 -0700976 restart_block->poll.ufds = ufds;
977 restart_block->poll.nfds = nfds;
978
979 if (timeout_msecs >= 0) {
980 restart_block->poll.tv_sec = end_time.tv_sec;
981 restart_block->poll.tv_nsec = end_time.tv_nsec;
982 restart_block->poll.has_timeout = 1;
983 } else
984 restart_block->poll.has_timeout = 0;
985
Chris Wright3075d9d2007-10-16 23:27:18 -0700986 ret = -ERESTART_RESTARTBLOCK;
987 }
988 return ret;
David Woodhouse9f729492006-01-18 17:44:05 -0800989}
990
Heiko Carstensd4e82042009-01-14 14:14:34 +0100991SYSCALL_DEFINE5(ppoll, struct pollfd __user *, ufds, unsigned int, nfds,
992 struct timespec __user *, tsp, const sigset_t __user *, sigmask,
993 size_t, sigsetsize)
David Woodhouse9f729492006-01-18 17:44:05 -0800994{
995 sigset_t ksigmask, sigsaved;
Arjan van de Ven8ff3e8e2008-08-31 08:26:40 -0700996 struct timespec ts, end_time, *to = NULL;
David Woodhouse9f729492006-01-18 17:44:05 -0800997 int ret;
998
999 if (tsp) {
1000 if (copy_from_user(&ts, tsp, sizeof(ts)))
1001 return -EFAULT;
1002
Arjan van de Ven8ff3e8e2008-08-31 08:26:40 -07001003 to = &end_time;
1004 if (poll_select_set_timeout(to, ts.tv_sec, ts.tv_nsec))
1005 return -EINVAL;
David Woodhouse9f729492006-01-18 17:44:05 -08001006 }
1007
1008 if (sigmask) {
1009 /* XXX: Don't preclude handling different sized sigset_t's. */
1010 if (sigsetsize != sizeof(sigset_t))
1011 return -EINVAL;
1012 if (copy_from_user(&ksigmask, sigmask, sizeof(ksigmask)))
1013 return -EFAULT;
1014
1015 sigdelsetmask(&ksigmask, sigmask(SIGKILL)|sigmask(SIGSTOP));
1016 sigprocmask(SIG_SETMASK, &ksigmask, &sigsaved);
1017 }
1018
Arjan van de Ven8ff3e8e2008-08-31 08:26:40 -07001019 ret = do_sys_poll(ufds, nfds, to);
David Woodhouse9f729492006-01-18 17:44:05 -08001020
1021 /* We can restart this syscall, usually */
1022 if (ret == -EINTR) {
1023 /*
1024 * Don't restore the signal mask yet. Let do_signal() deliver
1025 * the signal on the way back to userspace, before the signal
1026 * mask is restored.
1027 */
1028 if (sigmask) {
1029 memcpy(&current->saved_sigmask, &sigsaved,
1030 sizeof(sigsaved));
Roland McGrath4e4c22c2008-04-30 00:53:06 -07001031 set_restore_sigmask();
David Woodhouse9f729492006-01-18 17:44:05 -08001032 }
1033 ret = -ERESTARTNOHAND;
1034 } else if (sigmask)
1035 sigprocmask(SIG_SETMASK, &sigsaved, NULL);
1036
Arjan van de Ven8ff3e8e2008-08-31 08:26:40 -07001037 ret = poll_select_copy_remaining(&end_time, tsp, 0, ret);
David Woodhouse9f729492006-01-18 17:44:05 -08001038
1039 return ret;
1040}