2 * This file contains the procedures for the handling of select and poll
4 * Created for Linux based loosely upon Mathius Lattner's minix
5 * patches by Peter MacDonald. Heavily edited by Linus.
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.
13 * Changed sys_poll()/do_poll() to use PAGE_SIZE chunk-based allocation
14 * of fds to overcome nfds < 16390 descriptors limit (Tigran Aivazian).
17 #include <linux/kernel.h>
18 #include <linux/sched.h>
19 #include <linux/syscalls.h>
20 #include <linux/export.h>
21 #include <linux/slab.h>
22 #include <linux/poll.h>
23 #include <linux/personality.h> /* for STICKY_TIMEOUTS */
24 #include <linux/file.h>
25 #include <linux/fdtable.h>
27 #include <linux/rcupdate.h>
28 #include <linux/hrtimer.h>
29 #include <linux/sched/rt.h>
30 #include <linux/freezer.h>
31 #include <net/busy_poll.h>
32 #include <linux/vmalloc.h>
34 #include <asm/uaccess.h>
38 * Estimate expected accuracy in ns from a timeval.
40 * After quite a bit of churning around, we've settled on
41 * a simple thing of taking 0.1% of the timeout as the
42 * slack, with a cap of 100 msec.
43 * "nice" tasks get a 0.5% slack instead.
45 * Consider this comment an open invitation to come up with even
49 #define MAX_SLACK (100 * NSEC_PER_MSEC)
51 static long __estimate_accuracy(struct timespec *tv)
59 if (task_nice(current) > 0)
60 divfactor = divfactor / 5;
62 if (tv->tv_sec > MAX_SLACK / (NSEC_PER_SEC/divfactor))
65 slack = tv->tv_nsec / divfactor;
66 slack += tv->tv_sec * (NSEC_PER_SEC/divfactor);
68 if (slack > MAX_SLACK)
74 long select_estimate_accuracy(struct timespec *tv)
80 * Realtime tasks get a slack of 0 for obvious reasons.
87 now = timespec_sub(*tv, now);
88 ret = __estimate_accuracy(&now);
89 if (ret < current->timer_slack_ns)
90 return current->timer_slack_ns;
96 struct poll_table_page {
97 struct poll_table_page * next;
98 struct poll_table_entry * entry;
99 struct poll_table_entry entries[0];
102 #define POLL_TABLE_FULL(table) \
103 ((unsigned long)((table)->entry+1) > PAGE_SIZE + (unsigned long)(table))
106 * Ok, Peter made a complicated, but straightforward multiple_wait() function.
107 * I have rewritten this, taking some shortcuts: This code may not be easy to
108 * follow, but it should be free of race-conditions, and it's practical. If you
109 * understand what I'm doing here, then you understand how the linux
110 * sleep/wakeup mechanism works.
112 * Two very simple procedures, poll_wait() and poll_freewait() make all the
113 * work. poll_wait() is an inline-function defined in <linux/poll.h>,
114 * as all select/poll functions have to call it to add an entry to the
117 static void __pollwait(struct file *filp, wait_queue_head_t *wait_address,
120 void poll_initwait(struct poll_wqueues *pwq)
122 init_poll_funcptr(&pwq->pt, __pollwait);
123 pwq->polling_task = current;
127 pwq->inline_index = 0;
129 EXPORT_SYMBOL(poll_initwait);
131 static void free_poll_entry(struct poll_table_entry *entry)
133 remove_wait_queue(entry->wait_address, &entry->wait);
137 void poll_freewait(struct poll_wqueues *pwq)
139 struct poll_table_page * p = pwq->table;
141 for (i = 0; i < pwq->inline_index; i++)
142 free_poll_entry(pwq->inline_entries + i);
144 struct poll_table_entry * entry;
145 struct poll_table_page *old;
150 free_poll_entry(entry);
151 } while (entry > p->entries);
154 free_page((unsigned long) old);
157 EXPORT_SYMBOL(poll_freewait);
159 static struct poll_table_entry *poll_get_entry(struct poll_wqueues *p)
161 struct poll_table_page *table = p->table;
163 if (p->inline_index < N_INLINE_POLL_ENTRIES)
164 return p->inline_entries + p->inline_index++;
166 if (!table || POLL_TABLE_FULL(table)) {
167 struct poll_table_page *new_table;
169 new_table = (struct poll_table_page *) __get_free_page(GFP_KERNEL);
174 new_table->entry = new_table->entries;
175 new_table->next = table;
176 p->table = new_table;
180 return table->entry++;
183 static int __pollwake(wait_queue_t *wait, unsigned mode, int sync, void *key)
185 struct poll_wqueues *pwq = wait->private;
186 DECLARE_WAITQUEUE(dummy_wait, pwq->polling_task);
189 * Although this function is called under waitqueue lock, LOCK
190 * doesn't imply write barrier and the users expect write
191 * barrier semantics on wakeup functions. The following
192 * smp_wmb() is equivalent to smp_wmb() in try_to_wake_up()
193 * and is paired with smp_store_mb() in poll_schedule_timeout.
199 * Perform the default wake up operation using a dummy
202 * TODO: This is hacky but there currently is no interface to
203 * pass in @sync. @sync is scheduled to be removed and once
204 * that happens, wake_up_process() can be used directly.
206 return default_wake_function(&dummy_wait, mode, sync, key);
209 static int pollwake(wait_queue_t *wait, unsigned mode, int sync, void *key)
211 struct poll_table_entry *entry;
213 entry = container_of(wait, struct poll_table_entry, wait);
214 if (key && !((unsigned long)key & entry->key))
216 return __pollwake(wait, mode, sync, key);
219 /* Add a new entry */
220 static void __pollwait(struct file *filp, wait_queue_head_t *wait_address,
223 struct poll_wqueues *pwq = container_of(p, struct poll_wqueues, pt);
224 struct poll_table_entry *entry = poll_get_entry(pwq);
227 entry->filp = get_file(filp);
228 entry->wait_address = wait_address;
229 entry->key = p->_key;
230 init_waitqueue_func_entry(&entry->wait, pollwake);
231 entry->wait.private = pwq;
232 add_wait_queue(wait_address, &entry->wait);
235 int poll_schedule_timeout(struct poll_wqueues *pwq, int state,
236 ktime_t *expires, unsigned long slack)
240 set_current_state(state);
242 rc = schedule_hrtimeout_range(expires, slack, HRTIMER_MODE_ABS);
243 __set_current_state(TASK_RUNNING);
246 * Prepare for the next iteration.
248 * The following smp_store_mb() serves two purposes. First, it's
249 * the counterpart rmb of the wmb in pollwake() such that data
250 * written before wake up is always visible after wake up.
251 * Second, the full barrier guarantees that triggered clearing
252 * doesn't pass event check of the next iteration. Note that
253 * this problem doesn't exist for the first iteration as
254 * add_wait_queue() has full barrier semantics.
256 smp_store_mb(pwq->triggered, 0);
260 EXPORT_SYMBOL(poll_schedule_timeout);
263 * poll_select_set_timeout - helper function to setup the timeout value
264 * @to: pointer to timespec variable for the final timeout
265 * @sec: seconds (from user space)
266 * @nsec: nanoseconds (from user space)
268 * Note, we do not use a timespec for the user space value here, That
269 * way we can use the function for timeval and compat interfaces as well.
271 * Returns -EINVAL if sec/nsec are not normalized. Otherwise 0.
273 int poll_select_set_timeout(struct timespec *to, long sec, long nsec)
275 struct timespec ts = {.tv_sec = sec, .tv_nsec = nsec};
277 if (!timespec_valid(&ts))
280 /* Optimize for the zero timeout value here */
282 to->tv_sec = to->tv_nsec = 0;
285 *to = timespec_add_safe(*to, ts);
290 static int poll_select_copy_remaining(struct timespec *end_time, void __user *p,
291 int timeval, int ret)
299 if (current->personality & STICKY_TIMEOUTS)
302 /* No update for zero timeout */
303 if (!end_time->tv_sec && !end_time->tv_nsec)
307 rts = timespec_sub(*end_time, rts);
309 rts.tv_sec = rts.tv_nsec = 0;
312 if (sizeof(rtv) > sizeof(rtv.tv_sec) + sizeof(rtv.tv_usec))
313 memset(&rtv, 0, sizeof(rtv));
314 rtv.tv_sec = rts.tv_sec;
315 rtv.tv_usec = rts.tv_nsec / NSEC_PER_USEC;
317 if (!copy_to_user(p, &rtv, sizeof(rtv)))
320 } else if (!copy_to_user(p, &rts, sizeof(rts)))
324 * If an application puts its timeval in read-only memory, we
325 * don't want the Linux-specific update to the timeval to
326 * cause a fault after the select has completed
327 * successfully. However, because we're not updating the
328 * timeval, we can't restart the system call.
332 if (ret == -ERESTARTNOHAND)
337 #define FDS_IN(fds, n) (fds->in + n)
338 #define FDS_OUT(fds, n) (fds->out + n)
339 #define FDS_EX(fds, n) (fds->ex + n)
341 #define BITS(fds, n) (*FDS_IN(fds, n)|*FDS_OUT(fds, n)|*FDS_EX(fds, n))
343 static int max_select_fd(unsigned long n, fd_set_bits *fds)
345 unsigned long *open_fds;
350 /* handle last in-complete long-word first */
351 set = ~(~0UL << (n & (BITS_PER_LONG-1)));
353 fdt = files_fdtable(current->files);
354 open_fds = fdt->open_fds + n;
359 if (!(set & ~*open_fds))
370 if (set & ~*open_fds)
379 max += n * BITS_PER_LONG;
385 #define POLLIN_SET (POLLRDNORM | POLLRDBAND | POLLIN | POLLHUP | POLLERR)
386 #define POLLOUT_SET (POLLWRBAND | POLLWRNORM | POLLOUT | POLLERR)
387 #define POLLEX_SET (POLLPRI)
389 static inline void wait_key_set(poll_table *wait, unsigned long in,
390 unsigned long out, unsigned long bit,
391 unsigned int ll_flag)
393 wait->_key = POLLEX_SET | ll_flag;
395 wait->_key |= POLLIN_SET;
397 wait->_key |= POLLOUT_SET;
400 int do_select(int n, fd_set_bits *fds, struct timespec *end_time)
402 ktime_t expire, *to = NULL;
403 struct poll_wqueues table;
405 int retval, i, timed_out = 0;
406 unsigned long slack = 0;
407 unsigned int busy_flag = net_busy_loop_on() ? POLL_BUSY_LOOP : 0;
408 unsigned long busy_end = 0;
411 retval = max_select_fd(n, fds);
418 poll_initwait(&table);
420 if (end_time && !end_time->tv_sec && !end_time->tv_nsec) {
425 if (end_time && !timed_out)
426 slack = select_estimate_accuracy(end_time);
430 unsigned long *rinp, *routp, *rexp, *inp, *outp, *exp;
431 bool can_busy_loop = false;
433 inp = fds->in; outp = fds->out; exp = fds->ex;
434 rinp = fds->res_in; routp = fds->res_out; rexp = fds->res_ex;
436 for (i = 0; i < n; ++rinp, ++routp, ++rexp) {
437 unsigned long in, out, ex, all_bits, bit = 1, mask, j;
438 unsigned long res_in = 0, res_out = 0, res_ex = 0;
440 in = *inp++; out = *outp++; ex = *exp++;
441 all_bits = in | out | ex;
447 for (j = 0; j < BITS_PER_LONG; ++j, ++i, bit <<= 1) {
451 if (!(bit & all_bits))
455 const struct file_operations *f_op;
457 mask = DEFAULT_POLLMASK;
459 wait_key_set(wait, in, out,
461 mask = (*f_op->poll)(f.file, wait);
464 if ((mask & POLLIN_SET) && (in & bit)) {
469 if ((mask & POLLOUT_SET) && (out & bit)) {
474 if ((mask & POLLEX_SET) && (ex & bit)) {
479 /* got something, stop busy polling */
481 can_busy_loop = false;
485 * only remember a returned
486 * POLL_BUSY_LOOP if we asked for it
488 } else if (busy_flag & mask)
489 can_busy_loop = true;
502 if (retval || timed_out || signal_pending(current))
505 retval = table.error;
509 /* only if found POLL_BUSY_LOOP sockets && not out of time */
510 if (can_busy_loop && !need_resched()) {
512 busy_end = busy_loop_end_time();
515 if (!busy_loop_timeout(busy_end))
521 * If this is the first loop and we have a timeout
522 * given, then we convert to ktime_t and set the to
523 * pointer to the expiry value.
525 if (end_time && !to) {
526 expire = timespec_to_ktime(*end_time);
530 if (!poll_schedule_timeout(&table, TASK_INTERRUPTIBLE,
535 poll_freewait(&table);
541 * We can actually return ERESTARTSYS instead of EINTR, but I'd
542 * like to be certain this leads to no problems. So I return
543 * EINTR just for safety.
545 * Update: ERESTARTSYS breaks at least the xview clock binary, so
546 * I'm trying ERESTARTNOHAND which restart only when you want to.
548 int core_sys_select(int n, fd_set __user *inp, fd_set __user *outp,
549 fd_set __user *exp, struct timespec *end_time)
554 size_t size, alloc_size;
556 /* Allocate small arguments on the stack to save memory and be faster */
557 long stack_fds[SELECT_STACK_ALLOC/sizeof(long)];
563 /* max_fds can increase, so grab it once to avoid race */
565 fdt = files_fdtable(current->files);
566 max_fds = fdt->max_fds;
572 * We need 6 bitmaps (in/out/ex for both incoming and outgoing),
573 * since we used fdset we need to allocate memory in units of
578 if (size > sizeof(stack_fds) / 6) {
579 /* Not enough space in on-stack array; must use kmalloc */
581 if (size > (SIZE_MAX / 6))
584 alloc_size = 6 * size;
585 bits = kmalloc(alloc_size, GFP_KERNEL|__GFP_NOWARN);
586 if (!bits && alloc_size > PAGE_SIZE)
587 bits = vmalloc(alloc_size);
593 fds.out = bits + size;
594 fds.ex = bits + 2*size;
595 fds.res_in = bits + 3*size;
596 fds.res_out = bits + 4*size;
597 fds.res_ex = bits + 5*size;
599 if ((ret = get_fd_set(n, inp, fds.in)) ||
600 (ret = get_fd_set(n, outp, fds.out)) ||
601 (ret = get_fd_set(n, exp, fds.ex)))
603 zero_fd_set(n, fds.res_in);
604 zero_fd_set(n, fds.res_out);
605 zero_fd_set(n, fds.res_ex);
607 ret = do_select(n, &fds, end_time);
612 ret = -ERESTARTNOHAND;
613 if (signal_pending(current))
618 if (set_fd_set(n, inp, fds.res_in) ||
619 set_fd_set(n, outp, fds.res_out) ||
620 set_fd_set(n, exp, fds.res_ex))
624 if (bits != stack_fds)
630 SYSCALL_DEFINE5(select, int, n, fd_set __user *, inp, fd_set __user *, outp,
631 fd_set __user *, exp, struct timeval __user *, tvp)
633 struct timespec end_time, *to = NULL;
638 if (copy_from_user(&tv, tvp, sizeof(tv)))
642 if (poll_select_set_timeout(to,
643 tv.tv_sec + (tv.tv_usec / USEC_PER_SEC),
644 (tv.tv_usec % USEC_PER_SEC) * NSEC_PER_USEC))
648 ret = core_sys_select(n, inp, outp, exp, to);
649 ret = poll_select_copy_remaining(&end_time, tvp, 1, ret);
654 static long do_pselect(int n, fd_set __user *inp, fd_set __user *outp,
655 fd_set __user *exp, struct timespec __user *tsp,
656 const sigset_t __user *sigmask, size_t sigsetsize)
658 sigset_t ksigmask, sigsaved;
659 struct timespec ts, end_time, *to = NULL;
663 if (copy_from_user(&ts, tsp, sizeof(ts)))
667 if (poll_select_set_timeout(to, ts.tv_sec, ts.tv_nsec))
672 /* XXX: Don't preclude handling different sized sigset_t's. */
673 if (sigsetsize != sizeof(sigset_t))
675 if (copy_from_user(&ksigmask, sigmask, sizeof(ksigmask)))
678 sigdelsetmask(&ksigmask, sigmask(SIGKILL)|sigmask(SIGSTOP));
679 sigprocmask(SIG_SETMASK, &ksigmask, &sigsaved);
682 ret = core_sys_select(n, inp, outp, exp, to);
683 ret = poll_select_copy_remaining(&end_time, tsp, 0, ret);
685 if (ret == -ERESTARTNOHAND) {
687 * Don't restore the signal mask yet. Let do_signal() deliver
688 * the signal on the way back to userspace, before the signal
692 memcpy(¤t->saved_sigmask, &sigsaved,
694 set_restore_sigmask();
697 sigprocmask(SIG_SETMASK, &sigsaved, NULL);
703 * Most architectures can't handle 7-argument syscalls. So we provide a
704 * 6-argument version where the sixth argument is a pointer to a structure
705 * which has a pointer to the sigset_t itself followed by a size_t containing
708 SYSCALL_DEFINE6(pselect6, int, n, fd_set __user *, inp, fd_set __user *, outp,
709 fd_set __user *, exp, struct timespec __user *, tsp,
712 size_t sigsetsize = 0;
713 sigset_t __user *up = NULL;
716 if (!access_ok(VERIFY_READ, sig, sizeof(void *)+sizeof(size_t))
717 || __get_user(up, (sigset_t __user * __user *)sig)
718 || __get_user(sigsetsize,
719 (size_t __user *)(sig+sizeof(void *))))
723 return do_pselect(n, inp, outp, exp, tsp, up, sigsetsize);
726 #ifdef __ARCH_WANT_SYS_OLD_SELECT
727 struct sel_arg_struct {
729 fd_set __user *inp, *outp, *exp;
730 struct timeval __user *tvp;
733 SYSCALL_DEFINE1(old_select, struct sel_arg_struct __user *, arg)
735 struct sel_arg_struct a;
737 if (copy_from_user(&a, arg, sizeof(a)))
739 return sys_select(a.n, a.inp, a.outp, a.exp, a.tvp);
744 struct poll_list *next;
746 struct pollfd entries[0];
749 #define POLLFD_PER_PAGE ((PAGE_SIZE-sizeof(struct poll_list)) / sizeof(struct pollfd))
752 * Fish for pollable events on the pollfd->fd file descriptor. We're only
753 * interested in events matching the pollfd->events mask, and the result
754 * matching that mask is both recorded in pollfd->revents and returned. The
755 * pwait poll_table will be used by the fd-provided poll handler for waiting,
756 * if pwait->_qproc is non-NULL.
758 static inline unsigned int do_pollfd(struct pollfd *pollfd, poll_table *pwait,
760 unsigned int busy_flag)
768 struct fd f = fdget(fd);
771 mask = DEFAULT_POLLMASK;
772 if (f.file->f_op->poll) {
773 pwait->_key = pollfd->events|POLLERR|POLLHUP;
774 pwait->_key |= busy_flag;
775 mask = f.file->f_op->poll(f.file, pwait);
776 if (mask & busy_flag)
777 *can_busy_poll = true;
779 /* Mask out unneeded events. */
780 mask &= pollfd->events | POLLERR | POLLHUP;
784 pollfd->revents = mask;
789 static int do_poll(unsigned int nfds, struct poll_list *list,
790 struct poll_wqueues *wait, struct timespec *end_time)
792 poll_table* pt = &wait->pt;
793 ktime_t expire, *to = NULL;
794 int timed_out = 0, count = 0;
795 unsigned long slack = 0;
796 unsigned int busy_flag = net_busy_loop_on() ? POLL_BUSY_LOOP : 0;
797 unsigned long busy_end = 0;
799 /* Optimise the no-wait case */
800 if (end_time && !end_time->tv_sec && !end_time->tv_nsec) {
805 if (end_time && !timed_out)
806 slack = select_estimate_accuracy(end_time);
809 struct poll_list *walk;
810 bool can_busy_loop = false;
812 for (walk = list; walk != NULL; walk = walk->next) {
813 struct pollfd * pfd, * pfd_end;
816 pfd_end = pfd + walk->len;
817 for (; pfd != pfd_end; pfd++) {
819 * Fish for events. If we found one, record it
820 * and kill poll_table->_qproc, so we don't
821 * needlessly register any other waiters after
822 * this. They'll get immediately deregistered
823 * when we break out and return.
825 if (do_pollfd(pfd, pt, &can_busy_loop,
829 /* found something, stop busy polling */
831 can_busy_loop = false;
836 * All waiters have already been registered, so don't provide
837 * a poll_table->_qproc to them on the next loop iteration.
842 if (signal_pending(current))
845 if (count || timed_out)
848 /* only if found POLL_BUSY_LOOP sockets && not out of time */
849 if (can_busy_loop && !need_resched()) {
851 busy_end = busy_loop_end_time();
854 if (!busy_loop_timeout(busy_end))
860 * If this is the first loop and we have a timeout
861 * given, then we convert to ktime_t and set the to
862 * pointer to the expiry value.
864 if (end_time && !to) {
865 expire = timespec_to_ktime(*end_time);
869 if (!poll_schedule_timeout(wait, TASK_INTERRUPTIBLE, to, slack))
875 #define N_STACK_PPS ((sizeof(stack_pps) - sizeof(struct poll_list)) / \
876 sizeof(struct pollfd))
878 int do_sys_poll(struct pollfd __user *ufds, unsigned int nfds,
879 struct timespec *end_time)
881 struct poll_wqueues table;
882 int err = -EFAULT, fdcount, len, size;
883 /* Allocate small arguments on the stack to save memory and be
884 faster - use long to make sure the buffer is aligned properly
885 on 64 bit archs to avoid unaligned access */
886 long stack_pps[POLL_STACK_ALLOC/sizeof(long)];
887 struct poll_list *const head = (struct poll_list *)stack_pps;
888 struct poll_list *walk = head;
889 unsigned long todo = nfds;
891 if (nfds > rlimit(RLIMIT_NOFILE))
894 len = min_t(unsigned int, nfds, N_STACK_PPS);
901 if (copy_from_user(walk->entries, ufds + nfds-todo,
902 sizeof(struct pollfd) * walk->len))
909 len = min(todo, POLLFD_PER_PAGE);
910 size = sizeof(struct poll_list) + sizeof(struct pollfd) * len;
911 walk = walk->next = kmalloc(size, GFP_KERNEL);
918 poll_initwait(&table);
919 fdcount = do_poll(nfds, head, &table, end_time);
920 poll_freewait(&table);
922 for (walk = head; walk; walk = walk->next) {
923 struct pollfd *fds = walk->entries;
926 for (j = 0; j < walk->len; j++, ufds++)
927 if (__put_user(fds[j].revents, &ufds->revents))
935 struct poll_list *pos = walk;
943 static long do_restart_poll(struct restart_block *restart_block)
945 struct pollfd __user *ufds = restart_block->poll.ufds;
946 int nfds = restart_block->poll.nfds;
947 struct timespec *to = NULL, end_time;
950 if (restart_block->poll.has_timeout) {
951 end_time.tv_sec = restart_block->poll.tv_sec;
952 end_time.tv_nsec = restart_block->poll.tv_nsec;
956 ret = do_sys_poll(ufds, nfds, to);
959 restart_block->fn = do_restart_poll;
960 ret = -ERESTART_RESTARTBLOCK;
965 SYSCALL_DEFINE3(poll, struct pollfd __user *, ufds, unsigned int, nfds,
968 struct timespec end_time, *to = NULL;
971 if (timeout_msecs >= 0) {
973 poll_select_set_timeout(to, timeout_msecs / MSEC_PER_SEC,
974 NSEC_PER_MSEC * (timeout_msecs % MSEC_PER_SEC));
977 ret = do_sys_poll(ufds, nfds, to);
980 struct restart_block *restart_block;
982 restart_block = ¤t->restart_block;
983 restart_block->fn = do_restart_poll;
984 restart_block->poll.ufds = ufds;
985 restart_block->poll.nfds = nfds;
987 if (timeout_msecs >= 0) {
988 restart_block->poll.tv_sec = end_time.tv_sec;
989 restart_block->poll.tv_nsec = end_time.tv_nsec;
990 restart_block->poll.has_timeout = 1;
992 restart_block->poll.has_timeout = 0;
994 ret = -ERESTART_RESTARTBLOCK;
999 SYSCALL_DEFINE5(ppoll, struct pollfd __user *, ufds, unsigned int, nfds,
1000 struct timespec __user *, tsp, const sigset_t __user *, sigmask,
1003 sigset_t ksigmask, sigsaved;
1004 struct timespec ts, end_time, *to = NULL;
1008 if (copy_from_user(&ts, tsp, sizeof(ts)))
1012 if (poll_select_set_timeout(to, ts.tv_sec, ts.tv_nsec))
1017 /* XXX: Don't preclude handling different sized sigset_t's. */
1018 if (sigsetsize != sizeof(sigset_t))
1020 if (copy_from_user(&ksigmask, sigmask, sizeof(ksigmask)))
1023 sigdelsetmask(&ksigmask, sigmask(SIGKILL)|sigmask(SIGSTOP));
1024 sigprocmask(SIG_SETMASK, &ksigmask, &sigsaved);
1027 ret = do_sys_poll(ufds, nfds, to);
1029 /* We can restart this syscall, usually */
1030 if (ret == -EINTR) {
1032 * Don't restore the signal mask yet. Let do_signal() deliver
1033 * the signal on the way back to userspace, before the signal
1037 memcpy(¤t->saved_sigmask, &sigsaved,
1039 set_restore_sigmask();
1041 ret = -ERESTARTNOHAND;
1043 sigprocmask(SIG_SETMASK, &sigsaved, NULL);
1045 ret = poll_select_copy_remaining(&end_time, tsp, 0, ret);