blob: 08b91beed80644a3cd35c95a33bdff120b42a4e1 [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>
Linus Torvalds1da177e2005-04-16 15:20:36 -070018#include <linux/syscalls.h>
19#include <linux/module.h>
20#include <linux/slab.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070021#include <linux/poll.h>
22#include <linux/personality.h> /* for STICKY_TIMEOUTS */
23#include <linux/file.h>
Al Viro9f3acc32008-04-24 07:44:08 -040024#include <linux/fdtable.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070025#include <linux/fs.h>
Dipankar Sarmab8359962005-09-09 13:04:14 -070026#include <linux/rcupdate.h>
Arjan van de Ven8ff3e8e2008-08-31 08:26:40 -070027#include <linux/hrtimer.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070028
29#include <asm/uaccess.h>
30
Arjan van de Ven90d6e242008-09-01 15:55:35 -070031
32/*
33 * Estimate expected accuracy in ns from a timeval.
34 *
35 * After quite a bit of churning around, we've settled on
36 * a simple thing of taking 0.1% of the timeout as the
37 * slack, with a cap of 100 msec.
38 * "nice" tasks get a 0.5% slack instead.
39 *
40 * Consider this comment an open invitation to come up with even
41 * better solutions..
42 */
43
Arjan van de Ven96d2ab42008-09-07 16:08:55 -070044static long __estimate_accuracy(struct timespec *tv)
Arjan van de Ven90d6e242008-09-01 15:55:35 -070045{
Arjan van de Ven96d2ab42008-09-07 16:08:55 -070046 long slack;
Arjan van de Ven90d6e242008-09-01 15:55:35 -070047 int divfactor = 1000;
48
Arjan van de Ven4ce105d2008-09-07 15:31:39 -070049 if (task_nice(current) > 0)
Arjan van de Ven90d6e242008-09-01 15:55:35 -070050 divfactor = divfactor / 5;
51
52 slack = tv->tv_nsec / divfactor;
53 slack += tv->tv_sec * (NSEC_PER_SEC/divfactor);
54
55 if (slack > 100 * NSEC_PER_MSEC)
56 slack = 100 * NSEC_PER_MSEC;
Arjan van de Ven96d2ab42008-09-07 16:08:55 -070057
58 if (slack < 0)
59 slack = 0;
Arjan van de Ven90d6e242008-09-01 15:55:35 -070060 return slack;
61}
62
Arjan van de Ven96d2ab42008-09-07 16:08:55 -070063static long estimate_accuracy(struct timespec *tv)
Arjan van de Ven90d6e242008-09-01 15:55:35 -070064{
65 unsigned long ret;
66 struct timespec now;
67
68 /*
69 * Realtime tasks get a slack of 0 for obvious reasons.
70 */
71
Arjan van de Ven4ce105d2008-09-07 15:31:39 -070072 if (rt_task(current))
Arjan van de Ven90d6e242008-09-01 15:55:35 -070073 return 0;
74
75 ktime_get_ts(&now);
76 now = timespec_sub(*tv, now);
77 ret = __estimate_accuracy(&now);
78 if (ret < current->timer_slack_ns)
79 return current->timer_slack_ns;
80 return ret;
81}
82
83
84
Linus Torvalds1da177e2005-04-16 15:20:36 -070085struct poll_table_page {
86 struct poll_table_page * next;
87 struct poll_table_entry * entry;
88 struct poll_table_entry entries[0];
89};
90
91#define POLL_TABLE_FULL(table) \
92 ((unsigned long)((table)->entry+1) > PAGE_SIZE + (unsigned long)(table))
93
94/*
95 * Ok, Peter made a complicated, but straightforward multiple_wait() function.
96 * I have rewritten this, taking some shortcuts: This code may not be easy to
97 * follow, but it should be free of race-conditions, and it's practical. If you
98 * understand what I'm doing here, then you understand how the linux
99 * sleep/wakeup mechanism works.
100 *
101 * Two very simple procedures, poll_wait() and poll_freewait() make all the
102 * work. poll_wait() is an inline-function defined in <linux/poll.h>,
103 * as all select/poll functions have to call it to add an entry to the
104 * poll table.
105 */
Adrian Bunk75c96f82005-05-05 16:16:09 -0700106static void __pollwait(struct file *filp, wait_queue_head_t *wait_address,
107 poll_table *p);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700108
109void poll_initwait(struct poll_wqueues *pwq)
110{
111 init_poll_funcptr(&pwq->pt, __pollwait);
Tejun Heo5f820f62009-01-06 14:40:59 -0800112 pwq->polling_task = current;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700113 pwq->error = 0;
114 pwq->table = NULL;
Andi Kleen70674f92006-03-28 01:56:33 -0800115 pwq->inline_index = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700116}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700117EXPORT_SYMBOL(poll_initwait);
118
Andi Kleen70674f92006-03-28 01:56:33 -0800119static void free_poll_entry(struct poll_table_entry *entry)
120{
WANG Congccf67802007-05-09 07:10:02 +0200121 remove_wait_queue(entry->wait_address, &entry->wait);
Andi Kleen70674f92006-03-28 01:56:33 -0800122 fput(entry->filp);
123}
124
Linus Torvalds1da177e2005-04-16 15:20:36 -0700125void poll_freewait(struct poll_wqueues *pwq)
126{
127 struct poll_table_page * p = pwq->table;
Andi Kleen70674f92006-03-28 01:56:33 -0800128 int i;
129 for (i = 0; i < pwq->inline_index; i++)
130 free_poll_entry(pwq->inline_entries + i);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700131 while (p) {
132 struct poll_table_entry * entry;
133 struct poll_table_page *old;
134
135 entry = p->entry;
136 do {
137 entry--;
Andi Kleen70674f92006-03-28 01:56:33 -0800138 free_poll_entry(entry);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700139 } while (entry > p->entries);
140 old = p;
141 p = p->next;
142 free_page((unsigned long) old);
143 }
144}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700145EXPORT_SYMBOL(poll_freewait);
146
Tejun Heo5f820f62009-01-06 14:40:59 -0800147static struct poll_table_entry *poll_get_entry(struct poll_wqueues *p)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700148{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700149 struct poll_table_page *table = p->table;
150
Andi Kleen70674f92006-03-28 01:56:33 -0800151 if (p->inline_index < N_INLINE_POLL_ENTRIES)
152 return p->inline_entries + p->inline_index++;
153
Linus Torvalds1da177e2005-04-16 15:20:36 -0700154 if (!table || POLL_TABLE_FULL(table)) {
155 struct poll_table_page *new_table;
156
157 new_table = (struct poll_table_page *) __get_free_page(GFP_KERNEL);
158 if (!new_table) {
159 p->error = -ENOMEM;
Andi Kleen70674f92006-03-28 01:56:33 -0800160 return NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700161 }
162 new_table->entry = new_table->entries;
163 new_table->next = table;
164 p->table = new_table;
165 table = new_table;
166 }
167
Andi Kleen70674f92006-03-28 01:56:33 -0800168 return table->entry++;
169}
170
Tejun Heo5f820f62009-01-06 14:40:59 -0800171static int pollwake(wait_queue_t *wait, unsigned mode, int sync, void *key)
172{
173 struct poll_wqueues *pwq = wait->private;
174 DECLARE_WAITQUEUE(dummy_wait, pwq->polling_task);
175
176 /*
177 * Although this function is called under waitqueue lock, LOCK
178 * doesn't imply write barrier and the users expect write
179 * barrier semantics on wakeup functions. The following
180 * smp_wmb() is equivalent to smp_wmb() in try_to_wake_up()
181 * and is paired with set_mb() in poll_schedule_timeout.
182 */
183 smp_wmb();
184 pwq->triggered = 1;
185
186 /*
187 * Perform the default wake up operation using a dummy
188 * waitqueue.
189 *
190 * TODO: This is hacky but there currently is no interface to
191 * pass in @sync. @sync is scheduled to be removed and once
192 * that happens, wake_up_process() can be used directly.
193 */
194 return default_wake_function(&dummy_wait, mode, sync, key);
195}
196
Andi Kleen70674f92006-03-28 01:56:33 -0800197/* Add a new entry */
198static void __pollwait(struct file *filp, wait_queue_head_t *wait_address,
199 poll_table *p)
200{
Tejun Heo5f820f62009-01-06 14:40:59 -0800201 struct poll_wqueues *pwq = container_of(p, struct poll_wqueues, pt);
202 struct poll_table_entry *entry = poll_get_entry(pwq);
Andi Kleen70674f92006-03-28 01:56:33 -0800203 if (!entry)
204 return;
205 get_file(filp);
206 entry->filp = filp;
207 entry->wait_address = wait_address;
Tejun Heo5f820f62009-01-06 14:40:59 -0800208 init_waitqueue_func_entry(&entry->wait, pollwake);
209 entry->wait.private = pwq;
WANG Congccf67802007-05-09 07:10:02 +0200210 add_wait_queue(wait_address, &entry->wait);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700211}
212
Tejun Heo5f820f62009-01-06 14:40:59 -0800213int poll_schedule_timeout(struct poll_wqueues *pwq, int state,
214 ktime_t *expires, unsigned long slack)
215{
216 int rc = -EINTR;
217
218 set_current_state(state);
219 if (!pwq->triggered)
220 rc = schedule_hrtimeout_range(expires, slack, HRTIMER_MODE_ABS);
221 __set_current_state(TASK_RUNNING);
222
223 /*
224 * Prepare for the next iteration.
225 *
226 * The following set_mb() serves two purposes. First, it's
227 * the counterpart rmb of the wmb in pollwake() such that data
228 * written before wake up is always visible after wake up.
229 * Second, the full barrier guarantees that triggered clearing
230 * doesn't pass event check of the next iteration. Note that
231 * this problem doesn't exist for the first iteration as
232 * add_wait_queue() has full barrier semantics.
233 */
234 set_mb(pwq->triggered, 0);
235
236 return rc;
237}
238EXPORT_SYMBOL(poll_schedule_timeout);
239
Thomas Gleixnerb773ad42008-08-31 08:16:57 -0700240/**
241 * poll_select_set_timeout - helper function to setup the timeout value
242 * @to: pointer to timespec variable for the final timeout
243 * @sec: seconds (from user space)
244 * @nsec: nanoseconds (from user space)
245 *
246 * Note, we do not use a timespec for the user space value here, That
247 * way we can use the function for timeval and compat interfaces as well.
248 *
249 * Returns -EINVAL if sec/nsec are not normalized. Otherwise 0.
250 */
251int poll_select_set_timeout(struct timespec *to, long sec, long nsec)
252{
253 struct timespec ts = {.tv_sec = sec, .tv_nsec = nsec};
254
255 if (!timespec_valid(&ts))
256 return -EINVAL;
257
258 /* Optimize for the zero timeout value here */
259 if (!sec && !nsec) {
260 to->tv_sec = to->tv_nsec = 0;
261 } else {
262 ktime_get_ts(to);
263 *to = timespec_add_safe(*to, ts);
264 }
265 return 0;
266}
267
268static int poll_select_copy_remaining(struct timespec *end_time, void __user *p,
269 int timeval, int ret)
270{
271 struct timespec rts;
272 struct timeval rtv;
273
274 if (!p)
275 return ret;
276
277 if (current->personality & STICKY_TIMEOUTS)
278 goto sticky;
279
280 /* No update for zero timeout */
281 if (!end_time->tv_sec && !end_time->tv_nsec)
282 return ret;
283
284 ktime_get_ts(&rts);
285 rts = timespec_sub(*end_time, rts);
286 if (rts.tv_sec < 0)
287 rts.tv_sec = rts.tv_nsec = 0;
288
289 if (timeval) {
290 rtv.tv_sec = rts.tv_sec;
291 rtv.tv_usec = rts.tv_nsec / NSEC_PER_USEC;
292
293 if (!copy_to_user(p, &rtv, sizeof(rtv)))
294 return ret;
295
296 } else if (!copy_to_user(p, &rts, sizeof(rts)))
297 return ret;
298
299 /*
300 * If an application puts its timeval in read-only memory, we
301 * don't want the Linux-specific update to the timeval to
302 * cause a fault after the select has completed
303 * successfully. However, because we're not updating the
304 * timeval, we can't restart the system call.
305 */
306
307sticky:
308 if (ret == -ERESTARTNOHAND)
309 ret = -EINTR;
310 return ret;
311}
312
Linus Torvalds1da177e2005-04-16 15:20:36 -0700313#define FDS_IN(fds, n) (fds->in + n)
314#define FDS_OUT(fds, n) (fds->out + n)
315#define FDS_EX(fds, n) (fds->ex + n)
316
317#define BITS(fds, n) (*FDS_IN(fds, n)|*FDS_OUT(fds, n)|*FDS_EX(fds, n))
318
319static int max_select_fd(unsigned long n, fd_set_bits *fds)
320{
321 unsigned long *open_fds;
322 unsigned long set;
323 int max;
Dipankar Sarmabadf1662005-09-09 13:04:10 -0700324 struct fdtable *fdt;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700325
326 /* handle last in-complete long-word first */
327 set = ~(~0UL << (n & (__NFDBITS-1)));
328 n /= __NFDBITS;
Dipankar Sarmabadf1662005-09-09 13:04:10 -0700329 fdt = files_fdtable(current->files);
330 open_fds = fdt->open_fds->fds_bits+n;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700331 max = 0;
332 if (set) {
333 set &= BITS(fds, n);
334 if (set) {
335 if (!(set & ~*open_fds))
336 goto get_max;
337 return -EBADF;
338 }
339 }
340 while (n) {
341 open_fds--;
342 n--;
343 set = BITS(fds, n);
344 if (!set)
345 continue;
346 if (set & ~*open_fds)
347 return -EBADF;
348 if (max)
349 continue;
350get_max:
351 do {
352 max++;
353 set >>= 1;
354 } while (set);
355 max += n * __NFDBITS;
356 }
357
358 return max;
359}
360
Linus Torvalds1da177e2005-04-16 15:20:36 -0700361#define POLLIN_SET (POLLRDNORM | POLLRDBAND | POLLIN | POLLHUP | POLLERR)
362#define POLLOUT_SET (POLLWRBAND | POLLWRNORM | POLLOUT | POLLERR)
363#define POLLEX_SET (POLLPRI)
364
Arjan van de Ven8ff3e8e2008-08-31 08:26:40 -0700365int do_select(int n, fd_set_bits *fds, struct timespec *end_time)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700366{
Arjan van de Ven8ff3e8e2008-08-31 08:26:40 -0700367 ktime_t expire, *to = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700368 struct poll_wqueues table;
369 poll_table *wait;
Arjan van de Ven8ff3e8e2008-08-31 08:26:40 -0700370 int retval, i, timed_out = 0;
Arjan van de Ven90d6e242008-09-01 15:55:35 -0700371 unsigned long slack = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700372
Dipankar Sarmab8359962005-09-09 13:04:14 -0700373 rcu_read_lock();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700374 retval = max_select_fd(n, fds);
Dipankar Sarmab8359962005-09-09 13:04:14 -0700375 rcu_read_unlock();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700376
377 if (retval < 0)
378 return retval;
379 n = retval;
380
381 poll_initwait(&table);
382 wait = &table.pt;
Arjan van de Ven8ff3e8e2008-08-31 08:26:40 -0700383 if (end_time && !end_time->tv_sec && !end_time->tv_nsec) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700384 wait = NULL;
Arjan van de Ven8ff3e8e2008-08-31 08:26:40 -0700385 timed_out = 1;
386 }
387
Arjan van de Ven96d2ab42008-09-07 16:08:55 -0700388 if (end_time && !timed_out)
Arjan van de Ven90d6e242008-09-01 15:55:35 -0700389 slack = estimate_accuracy(end_time);
390
Linus Torvalds1da177e2005-04-16 15:20:36 -0700391 retval = 0;
392 for (;;) {
393 unsigned long *rinp, *routp, *rexp, *inp, *outp, *exp;
394
Linus Torvalds1da177e2005-04-16 15:20:36 -0700395 inp = fds->in; outp = fds->out; exp = fds->ex;
396 rinp = fds->res_in; routp = fds->res_out; rexp = fds->res_ex;
397
398 for (i = 0; i < n; ++rinp, ++routp, ++rexp) {
399 unsigned long in, out, ex, all_bits, bit = 1, mask, j;
400 unsigned long res_in = 0, res_out = 0, res_ex = 0;
Arjan van de Ven99ac48f2006-03-28 01:56:41 -0800401 const struct file_operations *f_op = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700402 struct file *file = NULL;
403
404 in = *inp++; out = *outp++; ex = *exp++;
405 all_bits = in | out | ex;
406 if (all_bits == 0) {
407 i += __NFDBITS;
408 continue;
409 }
410
411 for (j = 0; j < __NFDBITS; ++j, ++i, bit <<= 1) {
Eric Dumazete4a1f122006-03-28 01:56:34 -0800412 int fput_needed;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700413 if (i >= n)
414 break;
415 if (!(bit & all_bits))
416 continue;
Eric Dumazete4a1f122006-03-28 01:56:34 -0800417 file = fget_light(i, &fput_needed);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700418 if (file) {
419 f_op = file->f_op;
420 mask = DEFAULT_POLLMASK;
421 if (f_op && f_op->poll)
422 mask = (*f_op->poll)(file, retval ? NULL : wait);
Eric Dumazete4a1f122006-03-28 01:56:34 -0800423 fput_light(file, fput_needed);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700424 if ((mask & POLLIN_SET) && (in & bit)) {
425 res_in |= bit;
426 retval++;
427 }
428 if ((mask & POLLOUT_SET) && (out & bit)) {
429 res_out |= bit;
430 retval++;
431 }
432 if ((mask & POLLEX_SET) && (ex & bit)) {
433 res_ex |= bit;
434 retval++;
435 }
436 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700437 }
438 if (res_in)
439 *rinp = res_in;
440 if (res_out)
441 *routp = res_out;
442 if (res_ex)
443 *rexp = res_ex;
Linus Torvalds55d85382008-06-22 12:23:15 -0700444 cond_resched();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700445 }
446 wait = NULL;
Arjan van de Ven8ff3e8e2008-08-31 08:26:40 -0700447 if (retval || timed_out || signal_pending(current))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700448 break;
Pavel Machekf5264482008-04-21 22:15:06 +0000449 if (table.error) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700450 retval = table.error;
451 break;
452 }
David Woodhouse9f729492006-01-18 17:44:05 -0800453
Arjan van de Ven8ff3e8e2008-08-31 08:26:40 -0700454 /*
455 * If this is the first loop and we have a timeout
456 * given, then we convert to ktime_t and set the to
457 * pointer to the expiry value.
458 */
459 if (end_time && !to) {
460 expire = timespec_to_ktime(*end_time);
461 to = &expire;
David Woodhouse9f729492006-01-18 17:44:05 -0800462 }
Arjan van de Ven8ff3e8e2008-08-31 08:26:40 -0700463
Tejun Heo5f820f62009-01-06 14:40:59 -0800464 if (!poll_schedule_timeout(&table, TASK_INTERRUPTIBLE,
465 to, slack))
Arjan van de Ven8ff3e8e2008-08-31 08:26:40 -0700466 timed_out = 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700467 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700468
469 poll_freewait(&table);
470
Linus Torvalds1da177e2005-04-16 15:20:36 -0700471 return retval;
472}
473
Linus Torvalds1da177e2005-04-16 15:20:36 -0700474/*
475 * We can actually return ERESTARTSYS instead of EINTR, but I'd
476 * like to be certain this leads to no problems. So I return
477 * EINTR just for safety.
478 *
479 * Update: ERESTARTSYS breaks at least the xview clock binary, so
480 * I'm trying ERESTARTNOHAND which restart only when you want to.
481 */
482#define MAX_SELECT_SECONDS \
483 ((unsigned long) (MAX_SCHEDULE_TIMEOUT / HZ)-1)
484
Al Viroa2dcb442008-04-23 14:05:15 -0400485int core_sys_select(int n, fd_set __user *inp, fd_set __user *outp,
Arjan van de Ven8ff3e8e2008-08-31 08:26:40 -0700486 fd_set __user *exp, struct timespec *end_time)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700487{
488 fd_set_bits fds;
Andrew Morton29ff2db2006-04-10 22:52:46 -0700489 void *bits;
Vadim Lobanovbbea9f62006-12-10 02:21:12 -0800490 int ret, max_fds;
Mitchell Blank Jrb04eb6a2006-04-10 22:54:08 -0700491 unsigned int size;
Dipankar Sarmabadf1662005-09-09 13:04:10 -0700492 struct fdtable *fdt;
Andi Kleen70674f92006-03-28 01:56:33 -0800493 /* Allocate small arguments on the stack to save memory and be faster */
Jes Sorensen30c14e42006-03-31 11:18:57 -0500494 long stack_fds[SELECT_STACK_ALLOC/sizeof(long)];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700495
Linus Torvalds1da177e2005-04-16 15:20:36 -0700496 ret = -EINVAL;
497 if (n < 0)
498 goto out_nofds;
499
Vadim Lobanovbbea9f62006-12-10 02:21:12 -0800500 /* max_fds can increase, so grab it once to avoid race */
Dipankar Sarmab8359962005-09-09 13:04:14 -0700501 rcu_read_lock();
Dipankar Sarmabadf1662005-09-09 13:04:10 -0700502 fdt = files_fdtable(current->files);
Vadim Lobanovbbea9f62006-12-10 02:21:12 -0800503 max_fds = fdt->max_fds;
Dipankar Sarmab8359962005-09-09 13:04:14 -0700504 rcu_read_unlock();
Vadim Lobanovbbea9f62006-12-10 02:21:12 -0800505 if (n > max_fds)
506 n = max_fds;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700507
508 /*
509 * We need 6 bitmaps (in/out/ex for both incoming and outgoing),
510 * since we used fdset we need to allocate memory in units of
511 * long-words.
512 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700513 size = FDS_BYTES(n);
Mitchell Blank Jrb04eb6a2006-04-10 22:54:08 -0700514 bits = stack_fds;
515 if (size > sizeof(stack_fds) / 6) {
516 /* Not enough space in on-stack array; must use kmalloc */
517 ret = -ENOMEM;
Andi Kleen70674f92006-03-28 01:56:33 -0800518 bits = kmalloc(6 * size, GFP_KERNEL);
Mitchell Blank Jrb04eb6a2006-04-10 22:54:08 -0700519 if (!bits)
520 goto out_nofds;
521 }
Andrew Morton29ff2db2006-04-10 22:52:46 -0700522 fds.in = bits;
523 fds.out = bits + size;
524 fds.ex = bits + 2*size;
525 fds.res_in = bits + 3*size;
526 fds.res_out = bits + 4*size;
527 fds.res_ex = bits + 5*size;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700528
529 if ((ret = get_fd_set(n, inp, fds.in)) ||
530 (ret = get_fd_set(n, outp, fds.out)) ||
531 (ret = get_fd_set(n, exp, fds.ex)))
532 goto out;
533 zero_fd_set(n, fds.res_in);
534 zero_fd_set(n, fds.res_out);
535 zero_fd_set(n, fds.res_ex);
536
Arjan van de Ven8ff3e8e2008-08-31 08:26:40 -0700537 ret = do_select(n, &fds, end_time);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700538
539 if (ret < 0)
540 goto out;
541 if (!ret) {
542 ret = -ERESTARTNOHAND;
543 if (signal_pending(current))
544 goto out;
545 ret = 0;
546 }
547
548 if (set_fd_set(n, inp, fds.res_in) ||
549 set_fd_set(n, outp, fds.res_out) ||
550 set_fd_set(n, exp, fds.res_ex))
551 ret = -EFAULT;
552
553out:
Andi Kleen70674f92006-03-28 01:56:33 -0800554 if (bits != stack_fds)
555 kfree(bits);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700556out_nofds:
557 return ret;
558}
559
David Woodhouse9f729492006-01-18 17:44:05 -0800560asmlinkage long sys_select(int n, fd_set __user *inp, fd_set __user *outp,
561 fd_set __user *exp, struct timeval __user *tvp)
562{
Arjan van de Ven8ff3e8e2008-08-31 08:26:40 -0700563 struct timespec end_time, *to = NULL;
David Woodhouse9f729492006-01-18 17:44:05 -0800564 struct timeval tv;
565 int ret;
566
567 if (tvp) {
568 if (copy_from_user(&tv, tvp, sizeof(tv)))
569 return -EFAULT;
570
Arjan van de Ven8ff3e8e2008-08-31 08:26:40 -0700571 to = &end_time;
Arjan van de Ven4d36a9e2008-10-25 12:41:41 -0700572 if (poll_select_set_timeout(to,
573 tv.tv_sec + (tv.tv_usec / USEC_PER_SEC),
574 (tv.tv_usec % USEC_PER_SEC) * NSEC_PER_USEC))
David Woodhouse9f729492006-01-18 17:44:05 -0800575 return -EINVAL;
David Woodhouse9f729492006-01-18 17:44:05 -0800576 }
577
Arjan van de Ven8ff3e8e2008-08-31 08:26:40 -0700578 ret = core_sys_select(n, inp, outp, exp, to);
579 ret = poll_select_copy_remaining(&end_time, tvp, 1, ret);
David Woodhouse9f729492006-01-18 17:44:05 -0800580
581 return ret;
582}
583
Roland McGrathf3de2722008-04-30 00:53:09 -0700584#ifdef HAVE_SET_RESTORE_SIGMASK
David Woodhouse9f729492006-01-18 17:44:05 -0800585asmlinkage long sys_pselect7(int n, fd_set __user *inp, fd_set __user *outp,
586 fd_set __user *exp, struct timespec __user *tsp,
587 const sigset_t __user *sigmask, size_t sigsetsize)
588{
David Woodhouse9f729492006-01-18 17:44:05 -0800589 sigset_t ksigmask, sigsaved;
Arjan van de Ven8ff3e8e2008-08-31 08:26:40 -0700590 struct timespec ts, end_time, *to = NULL;
David Woodhouse9f729492006-01-18 17:44:05 -0800591 int ret;
592
593 if (tsp) {
594 if (copy_from_user(&ts, tsp, sizeof(ts)))
595 return -EFAULT;
596
Arjan van de Ven8ff3e8e2008-08-31 08:26:40 -0700597 to = &end_time;
598 if (poll_select_set_timeout(to, ts.tv_sec, ts.tv_nsec))
David Woodhouse9f729492006-01-18 17:44:05 -0800599 return -EINVAL;
David Woodhouse9f729492006-01-18 17:44:05 -0800600 }
601
602 if (sigmask) {
603 /* XXX: Don't preclude handling different sized sigset_t's. */
604 if (sigsetsize != sizeof(sigset_t))
605 return -EINVAL;
606 if (copy_from_user(&ksigmask, sigmask, sizeof(ksigmask)))
607 return -EFAULT;
608
609 sigdelsetmask(&ksigmask, sigmask(SIGKILL)|sigmask(SIGSTOP));
610 sigprocmask(SIG_SETMASK, &ksigmask, &sigsaved);
611 }
612
Arjan van de Ven8ff3e8e2008-08-31 08:26:40 -0700613 ret = core_sys_select(n, inp, outp, exp, &end_time);
614 ret = poll_select_copy_remaining(&end_time, tsp, 0, ret);
David Woodhouse9f729492006-01-18 17:44:05 -0800615
616 if (ret == -ERESTARTNOHAND) {
617 /*
618 * Don't restore the signal mask yet. Let do_signal() deliver
619 * the signal on the way back to userspace, before the signal
620 * mask is restored.
621 */
622 if (sigmask) {
623 memcpy(&current->saved_sigmask, &sigsaved,
624 sizeof(sigsaved));
Roland McGrath4e4c22c2008-04-30 00:53:06 -0700625 set_restore_sigmask();
David Woodhouse9f729492006-01-18 17:44:05 -0800626 }
627 } else if (sigmask)
628 sigprocmask(SIG_SETMASK, &sigsaved, NULL);
629
630 return ret;
631}
632
633/*
634 * Most architectures can't handle 7-argument syscalls. So we provide a
635 * 6-argument version where the sixth argument is a pointer to a structure
636 * which has a pointer to the sigset_t itself followed by a size_t containing
637 * the sigset size.
638 */
639asmlinkage long sys_pselect6(int n, fd_set __user *inp, fd_set __user *outp,
640 fd_set __user *exp, struct timespec __user *tsp, void __user *sig)
641{
642 size_t sigsetsize = 0;
643 sigset_t __user *up = NULL;
644
645 if (sig) {
646 if (!access_ok(VERIFY_READ, sig, sizeof(void *)+sizeof(size_t))
Al Viroe110ab92006-02-01 05:26:09 -0500647 || __get_user(up, (sigset_t __user * __user *)sig)
David Woodhouse9f729492006-01-18 17:44:05 -0800648 || __get_user(sigsetsize,
Al Viroe110ab92006-02-01 05:26:09 -0500649 (size_t __user *)(sig+sizeof(void *))))
David Woodhouse9f729492006-01-18 17:44:05 -0800650 return -EFAULT;
651 }
652
653 return sys_pselect7(n, inp, outp, exp, tsp, up, sigsetsize);
654}
Roland McGrathf3de2722008-04-30 00:53:09 -0700655#endif /* HAVE_SET_RESTORE_SIGMASK */
David Woodhouse9f729492006-01-18 17:44:05 -0800656
Linus Torvalds1da177e2005-04-16 15:20:36 -0700657struct poll_list {
658 struct poll_list *next;
659 int len;
660 struct pollfd entries[0];
661};
662
663#define POLLFD_PER_PAGE ((PAGE_SIZE-sizeof(struct poll_list)) / sizeof(struct pollfd))
664
Vadim Lobanov4a4b69f2006-06-23 02:05:16 -0700665/*
666 * Fish for pollable events on the pollfd->fd file descriptor. We're only
667 * interested in events matching the pollfd->events mask, and the result
668 * matching that mask is both recorded in pollfd->revents and returned. The
669 * pwait poll_table will be used by the fd-provided poll handler for waiting,
670 * if non-NULL.
671 */
672static inline unsigned int do_pollfd(struct pollfd *pollfd, poll_table *pwait)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700673{
Vadim Lobanov4a4b69f2006-06-23 02:05:16 -0700674 unsigned int mask;
675 int fd;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700676
Vadim Lobanov4a4b69f2006-06-23 02:05:16 -0700677 mask = 0;
678 fd = pollfd->fd;
679 if (fd >= 0) {
680 int fput_needed;
681 struct file * file;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700682
Vadim Lobanov4a4b69f2006-06-23 02:05:16 -0700683 file = fget_light(fd, &fput_needed);
684 mask = POLLNVAL;
685 if (file != NULL) {
686 mask = DEFAULT_POLLMASK;
687 if (file->f_op && file->f_op->poll)
688 mask = file->f_op->poll(file, pwait);
689 /* Mask out unneeded events. */
690 mask &= pollfd->events | POLLERR | POLLHUP;
691 fput_light(file, fput_needed);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700692 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700693 }
Vadim Lobanov4a4b69f2006-06-23 02:05:16 -0700694 pollfd->revents = mask;
695
696 return mask;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700697}
698
699static int do_poll(unsigned int nfds, struct poll_list *list,
Arjan van de Ven8ff3e8e2008-08-31 08:26:40 -0700700 struct poll_wqueues *wait, struct timespec *end_time)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700701{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700702 poll_table* pt = &wait->pt;
Arjan van de Ven8ff3e8e2008-08-31 08:26:40 -0700703 ktime_t expire, *to = NULL;
704 int timed_out = 0, count = 0;
Arjan van de Ven90d6e242008-09-01 15:55:35 -0700705 unsigned long slack = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700706
David Woodhouse9f729492006-01-18 17:44:05 -0800707 /* Optimise the no-wait case */
Arjan van de Ven8ff3e8e2008-08-31 08:26:40 -0700708 if (end_time && !end_time->tv_sec && !end_time->tv_nsec) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700709 pt = NULL;
Arjan van de Ven8ff3e8e2008-08-31 08:26:40 -0700710 timed_out = 1;
711 }
Oleg Nesterov9bf084f2007-10-16 23:26:18 -0700712
Arjan van de Ven96d2ab42008-09-07 16:08:55 -0700713 if (end_time && !timed_out)
Arjan van de Ven90d6e242008-09-01 15:55:35 -0700714 slack = estimate_accuracy(end_time);
715
Linus Torvalds1da177e2005-04-16 15:20:36 -0700716 for (;;) {
717 struct poll_list *walk;
David Woodhouse9f729492006-01-18 17:44:05 -0800718
Vadim Lobanov4a4b69f2006-06-23 02:05:16 -0700719 for (walk = list; walk != NULL; walk = walk->next) {
720 struct pollfd * pfd, * pfd_end;
721
722 pfd = walk->entries;
723 pfd_end = pfd + walk->len;
724 for (; pfd != pfd_end; pfd++) {
725 /*
726 * Fish for events. If we found one, record it
727 * and kill the poll_table, so we don't
728 * needlessly register any other waiters after
729 * this. They'll get immediately deregistered
730 * when we break out and return.
731 */
732 if (do_pollfd(pfd, pt)) {
733 count++;
734 pt = NULL;
735 }
736 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700737 }
Vadim Lobanov4a4b69f2006-06-23 02:05:16 -0700738 /*
739 * All waiters have already been registered, so don't provide
740 * a poll_table to them on the next loop iteration.
741 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700742 pt = NULL;
Oleg Nesterov9bf084f2007-10-16 23:26:18 -0700743 if (!count) {
744 count = wait->error;
745 if (signal_pending(current))
746 count = -EINTR;
747 }
Arjan van de Ven8ff3e8e2008-08-31 08:26:40 -0700748 if (count || timed_out)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700749 break;
David Woodhouse9f729492006-01-18 17:44:05 -0800750
Arjan van de Ven8ff3e8e2008-08-31 08:26:40 -0700751 /*
752 * If this is the first loop and we have a timeout
753 * given, then we convert to ktime_t and set the to
754 * pointer to the expiry value.
755 */
756 if (end_time && !to) {
757 expire = timespec_to_ktime(*end_time);
758 to = &expire;
David Woodhouse9f729492006-01-18 17:44:05 -0800759 }
760
Tejun Heo5f820f62009-01-06 14:40:59 -0800761 if (!poll_schedule_timeout(wait, TASK_INTERRUPTIBLE, to, slack))
Arjan van de Ven8ff3e8e2008-08-31 08:26:40 -0700762 timed_out = 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700763 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700764 return count;
765}
766
Andi Kleen70674f92006-03-28 01:56:33 -0800767#define N_STACK_PPS ((sizeof(stack_pps) - sizeof(struct poll_list)) / \
768 sizeof(struct pollfd))
769
Arjan van de Ven8ff3e8e2008-08-31 08:26:40 -0700770int do_sys_poll(struct pollfd __user *ufds, unsigned int nfds,
771 struct timespec *end_time)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700772{
773 struct poll_wqueues table;
Oleg Nesterov252e5722007-10-16 23:26:17 -0700774 int err = -EFAULT, fdcount, len, size;
Jes Sorensen30c14e42006-03-31 11:18:57 -0500775 /* Allocate small arguments on the stack to save memory and be
776 faster - use long to make sure the buffer is aligned properly
777 on 64 bit archs to avoid unaligned access */
778 long stack_pps[POLL_STACK_ALLOC/sizeof(long)];
Oleg Nesterov252e5722007-10-16 23:26:17 -0700779 struct poll_list *const head = (struct poll_list *)stack_pps;
780 struct poll_list *walk = head;
781 unsigned long todo = nfds;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700782
Chris Snook4e6fd332006-09-29 02:01:33 -0700783 if (nfds > current->signal->rlim[RLIMIT_NOFILE].rlim_cur)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700784 return -EINVAL;
785
Oleg Nesterov252e5722007-10-16 23:26:17 -0700786 len = min_t(unsigned int, nfds, N_STACK_PPS);
787 for (;;) {
788 walk->next = NULL;
789 walk->len = len;
790 if (!len)
791 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700792
Oleg Nesterov252e5722007-10-16 23:26:17 -0700793 if (copy_from_user(walk->entries, ufds + nfds-todo,
794 sizeof(struct pollfd) * walk->len))
795 goto out_fds;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700796
Oleg Nesterov252e5722007-10-16 23:26:17 -0700797 todo -= walk->len;
798 if (!todo)
799 break;
800
801 len = min(todo, POLLFD_PER_PAGE);
802 size = sizeof(struct poll_list) + sizeof(struct pollfd) * len;
803 walk = walk->next = kmalloc(size, GFP_KERNEL);
804 if (!walk) {
805 err = -ENOMEM;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700806 goto out_fds;
807 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700808 }
David Woodhouse9f729492006-01-18 17:44:05 -0800809
Oleg Nesterov252e5722007-10-16 23:26:17 -0700810 poll_initwait(&table);
Arjan van de Ven8ff3e8e2008-08-31 08:26:40 -0700811 fdcount = do_poll(nfds, head, &table, end_time);
Oleg Nesterov252e5722007-10-16 23:26:17 -0700812 poll_freewait(&table);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700813
Oleg Nesterov252e5722007-10-16 23:26:17 -0700814 for (walk = head; walk; walk = walk->next) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700815 struct pollfd *fds = walk->entries;
816 int j;
817
Oleg Nesterov252e5722007-10-16 23:26:17 -0700818 for (j = 0; j < walk->len; j++, ufds++)
819 if (__put_user(fds[j].revents, &ufds->revents))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700820 goto out_fds;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700821 }
Oleg Nesterov252e5722007-10-16 23:26:17 -0700822
Linus Torvalds1da177e2005-04-16 15:20:36 -0700823 err = fdcount;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700824out_fds:
Oleg Nesterov252e5722007-10-16 23:26:17 -0700825 walk = head->next;
826 while (walk) {
827 struct poll_list *pos = walk;
828 walk = walk->next;
829 kfree(pos);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700830 }
Oleg Nesterov252e5722007-10-16 23:26:17 -0700831
Linus Torvalds1da177e2005-04-16 15:20:36 -0700832 return err;
833}
David Woodhouse9f729492006-01-18 17:44:05 -0800834
Chris Wright3075d9d2007-10-16 23:27:18 -0700835static long do_restart_poll(struct restart_block *restart_block)
836{
Arjan van de Ven8ff3e8e2008-08-31 08:26:40 -0700837 struct pollfd __user *ufds = restart_block->poll.ufds;
838 int nfds = restart_block->poll.nfds;
839 struct timespec *to = NULL, end_time;
Chris Wright3075d9d2007-10-16 23:27:18 -0700840 int ret;
841
Arjan van de Ven8ff3e8e2008-08-31 08:26:40 -0700842 if (restart_block->poll.has_timeout) {
843 end_time.tv_sec = restart_block->poll.tv_sec;
844 end_time.tv_nsec = restart_block->poll.tv_nsec;
845 to = &end_time;
846 }
847
848 ret = do_sys_poll(ufds, nfds, to);
849
Chris Wright3075d9d2007-10-16 23:27:18 -0700850 if (ret == -EINTR) {
851 restart_block->fn = do_restart_poll;
Chris Wright3075d9d2007-10-16 23:27:18 -0700852 ret = -ERESTART_RESTARTBLOCK;
853 }
854 return ret;
855}
856
David Woodhouse9f729492006-01-18 17:44:05 -0800857asmlinkage long sys_poll(struct pollfd __user *ufds, unsigned int nfds,
858 long timeout_msecs)
859{
Arjan van de Ven8ff3e8e2008-08-31 08:26:40 -0700860 struct timespec end_time, *to = NULL;
Chris Wright3075d9d2007-10-16 23:27:18 -0700861 int ret;
David Woodhouse9f729492006-01-18 17:44:05 -0800862
Arjan van de Ven8ff3e8e2008-08-31 08:26:40 -0700863 if (timeout_msecs >= 0) {
864 to = &end_time;
865 poll_select_set_timeout(to, timeout_msecs / MSEC_PER_SEC,
866 NSEC_PER_MSEC * (timeout_msecs % MSEC_PER_SEC));
David Woodhouse9f729492006-01-18 17:44:05 -0800867 }
868
Arjan van de Ven8ff3e8e2008-08-31 08:26:40 -0700869 ret = do_sys_poll(ufds, nfds, to);
870
Chris Wright3075d9d2007-10-16 23:27:18 -0700871 if (ret == -EINTR) {
872 struct restart_block *restart_block;
Arjan van de Ven8ff3e8e2008-08-31 08:26:40 -0700873
Chris Wright3075d9d2007-10-16 23:27:18 -0700874 restart_block = &current_thread_info()->restart_block;
875 restart_block->fn = do_restart_poll;
Arjan van de Ven8ff3e8e2008-08-31 08:26:40 -0700876 restart_block->poll.ufds = ufds;
877 restart_block->poll.nfds = nfds;
878
879 if (timeout_msecs >= 0) {
880 restart_block->poll.tv_sec = end_time.tv_sec;
881 restart_block->poll.tv_nsec = end_time.tv_nsec;
882 restart_block->poll.has_timeout = 1;
883 } else
884 restart_block->poll.has_timeout = 0;
885
Chris Wright3075d9d2007-10-16 23:27:18 -0700886 ret = -ERESTART_RESTARTBLOCK;
887 }
888 return ret;
David Woodhouse9f729492006-01-18 17:44:05 -0800889}
890
Roland McGrathf3de2722008-04-30 00:53:09 -0700891#ifdef HAVE_SET_RESTORE_SIGMASK
David Woodhouse9f729492006-01-18 17:44:05 -0800892asmlinkage long sys_ppoll(struct pollfd __user *ufds, unsigned int nfds,
893 struct timespec __user *tsp, const sigset_t __user *sigmask,
894 size_t sigsetsize)
895{
896 sigset_t ksigmask, sigsaved;
Arjan van de Ven8ff3e8e2008-08-31 08:26:40 -0700897 struct timespec ts, end_time, *to = NULL;
David Woodhouse9f729492006-01-18 17:44:05 -0800898 int ret;
899
900 if (tsp) {
901 if (copy_from_user(&ts, tsp, sizeof(ts)))
902 return -EFAULT;
903
Arjan van de Ven8ff3e8e2008-08-31 08:26:40 -0700904 to = &end_time;
905 if (poll_select_set_timeout(to, ts.tv_sec, ts.tv_nsec))
906 return -EINVAL;
David Woodhouse9f729492006-01-18 17:44:05 -0800907 }
908
909 if (sigmask) {
910 /* XXX: Don't preclude handling different sized sigset_t's. */
911 if (sigsetsize != sizeof(sigset_t))
912 return -EINVAL;
913 if (copy_from_user(&ksigmask, sigmask, sizeof(ksigmask)))
914 return -EFAULT;
915
916 sigdelsetmask(&ksigmask, sigmask(SIGKILL)|sigmask(SIGSTOP));
917 sigprocmask(SIG_SETMASK, &ksigmask, &sigsaved);
918 }
919
Arjan van de Ven8ff3e8e2008-08-31 08:26:40 -0700920 ret = do_sys_poll(ufds, nfds, to);
David Woodhouse9f729492006-01-18 17:44:05 -0800921
922 /* We can restart this syscall, usually */
923 if (ret == -EINTR) {
924 /*
925 * Don't restore the signal mask yet. Let do_signal() deliver
926 * the signal on the way back to userspace, before the signal
927 * mask is restored.
928 */
929 if (sigmask) {
930 memcpy(&current->saved_sigmask, &sigsaved,
931 sizeof(sigsaved));
Roland McGrath4e4c22c2008-04-30 00:53:06 -0700932 set_restore_sigmask();
David Woodhouse9f729492006-01-18 17:44:05 -0800933 }
934 ret = -ERESTARTNOHAND;
935 } else if (sigmask)
936 sigprocmask(SIG_SETMASK, &sigsaved, NULL);
937
Arjan van de Ven8ff3e8e2008-08-31 08:26:40 -0700938 ret = poll_select_copy_remaining(&end_time, tsp, 0, ret);
David Woodhouse9f729492006-01-18 17:44:05 -0800939
940 return ret;
941}
Roland McGrathf3de2722008-04-30 00:53:09 -0700942#endif /* HAVE_SET_RESTORE_SIGMASK */