]>
git.proxmox.com Git - mirror_ubuntu-artful-kernel.git/blob - fs/select.c
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/syscalls.h>
19 #include <linux/module.h>
20 #include <linux/slab.h>
21 #include <linux/poll.h>
22 #include <linux/personality.h> /* for STICKY_TIMEOUTS */
23 #include <linux/file.h>
25 #include <linux/rcupdate.h>
27 #include <asm/uaccess.h>
29 struct poll_table_page
{
30 struct poll_table_page
* next
;
31 struct poll_table_entry
* entry
;
32 struct poll_table_entry entries
[0];
35 #define POLL_TABLE_FULL(table) \
36 ((unsigned long)((table)->entry+1) > PAGE_SIZE + (unsigned long)(table))
39 * Ok, Peter made a complicated, but straightforward multiple_wait() function.
40 * I have rewritten this, taking some shortcuts: This code may not be easy to
41 * follow, but it should be free of race-conditions, and it's practical. If you
42 * understand what I'm doing here, then you understand how the linux
43 * sleep/wakeup mechanism works.
45 * Two very simple procedures, poll_wait() and poll_freewait() make all the
46 * work. poll_wait() is an inline-function defined in <linux/poll.h>,
47 * as all select/poll functions have to call it to add an entry to the
50 static void __pollwait(struct file
*filp
, wait_queue_head_t
*wait_address
,
53 void poll_initwait(struct poll_wqueues
*pwq
)
55 init_poll_funcptr(&pwq
->pt
, __pollwait
);
58 pwq
->inline_index
= 0;
61 EXPORT_SYMBOL(poll_initwait
);
63 static void free_poll_entry(struct poll_table_entry
*entry
)
65 remove_wait_queue(entry
->wait_address
, &entry
->wait
);
69 void poll_freewait(struct poll_wqueues
*pwq
)
71 struct poll_table_page
* p
= pwq
->table
;
73 for (i
= 0; i
< pwq
->inline_index
; i
++)
74 free_poll_entry(pwq
->inline_entries
+ i
);
76 struct poll_table_entry
* entry
;
77 struct poll_table_page
*old
;
82 free_poll_entry(entry
);
83 } while (entry
> p
->entries
);
86 free_page((unsigned long) old
);
90 EXPORT_SYMBOL(poll_freewait
);
92 static struct poll_table_entry
*poll_get_entry(poll_table
*_p
)
94 struct poll_wqueues
*p
= container_of(_p
, struct poll_wqueues
, pt
);
95 struct poll_table_page
*table
= p
->table
;
97 if (p
->inline_index
< N_INLINE_POLL_ENTRIES
)
98 return p
->inline_entries
+ p
->inline_index
++;
100 if (!table
|| POLL_TABLE_FULL(table
)) {
101 struct poll_table_page
*new_table
;
103 new_table
= (struct poll_table_page
*) __get_free_page(GFP_KERNEL
);
106 __set_current_state(TASK_RUNNING
);
109 new_table
->entry
= new_table
->entries
;
110 new_table
->next
= table
;
111 p
->table
= new_table
;
115 return table
->entry
++;
118 /* Add a new entry */
119 static void __pollwait(struct file
*filp
, wait_queue_head_t
*wait_address
,
122 struct poll_table_entry
*entry
= poll_get_entry(p
);
127 entry
->wait_address
= wait_address
;
128 init_waitqueue_entry(&entry
->wait
, current
);
129 add_wait_queue(wait_address
, &entry
->wait
);
132 #define FDS_IN(fds, n) (fds->in + n)
133 #define FDS_OUT(fds, n) (fds->out + n)
134 #define FDS_EX(fds, n) (fds->ex + n)
136 #define BITS(fds, n) (*FDS_IN(fds, n)|*FDS_OUT(fds, n)|*FDS_EX(fds, n))
138 static int max_select_fd(unsigned long n
, fd_set_bits
*fds
)
140 unsigned long *open_fds
;
145 /* handle last in-complete long-word first */
146 set
= ~(~0UL << (n
& (__NFDBITS
-1)));
148 fdt
= files_fdtable(current
->files
);
149 open_fds
= fdt
->open_fds
->fds_bits
+n
;
154 if (!(set
& ~*open_fds
))
165 if (set
& ~*open_fds
)
174 max
+= n
* __NFDBITS
;
180 #define BIT(i) (1UL << ((i)&(__NFDBITS-1)))
181 #define MEM(i,m) ((m)+(unsigned)(i)/__NFDBITS)
182 #define ISSET(i,m) (((i)&*(m)) != 0)
183 #define SET(i,m) (*(m) |= (i))
185 #define POLLIN_SET (POLLRDNORM | POLLRDBAND | POLLIN | POLLHUP | POLLERR)
186 #define POLLOUT_SET (POLLWRBAND | POLLWRNORM | POLLOUT | POLLERR)
187 #define POLLEX_SET (POLLPRI)
189 int do_select(int n
, fd_set_bits
*fds
, s64
*timeout
)
191 struct poll_wqueues table
;
196 retval
= max_select_fd(n
, fds
);
203 poll_initwait(&table
);
209 unsigned long *rinp
, *routp
, *rexp
, *inp
, *outp
, *exp
;
212 set_current_state(TASK_INTERRUPTIBLE
);
214 inp
= fds
->in
; outp
= fds
->out
; exp
= fds
->ex
;
215 rinp
= fds
->res_in
; routp
= fds
->res_out
; rexp
= fds
->res_ex
;
217 for (i
= 0; i
< n
; ++rinp
, ++routp
, ++rexp
) {
218 unsigned long in
, out
, ex
, all_bits
, bit
= 1, mask
, j
;
219 unsigned long res_in
= 0, res_out
= 0, res_ex
= 0;
220 const struct file_operations
*f_op
= NULL
;
221 struct file
*file
= NULL
;
223 in
= *inp
++; out
= *outp
++; ex
= *exp
++;
224 all_bits
= in
| out
| ex
;
230 for (j
= 0; j
< __NFDBITS
; ++j
, ++i
, bit
<<= 1) {
234 if (!(bit
& all_bits
))
236 file
= fget_light(i
, &fput_needed
);
239 mask
= DEFAULT_POLLMASK
;
240 if (f_op
&& f_op
->poll
)
241 mask
= (*f_op
->poll
)(file
, retval
? NULL
: wait
);
242 fput_light(file
, fput_needed
);
243 if ((mask
& POLLIN_SET
) && (in
& bit
)) {
247 if ((mask
& POLLOUT_SET
) && (out
& bit
)) {
251 if ((mask
& POLLEX_SET
) && (ex
& bit
)) {
266 if (retval
|| !*timeout
|| signal_pending(current
))
269 retval
= table
.error
;
274 /* Wait indefinitely */
275 __timeout
= MAX_SCHEDULE_TIMEOUT
;
276 } else if (unlikely(*timeout
>= (s64
)MAX_SCHEDULE_TIMEOUT
- 1)) {
277 /* Wait for longer than MAX_SCHEDULE_TIMEOUT. Do it in a loop */
278 __timeout
= MAX_SCHEDULE_TIMEOUT
- 1;
279 *timeout
-= __timeout
;
281 __timeout
= *timeout
;
284 __timeout
= schedule_timeout(__timeout
);
286 *timeout
+= __timeout
;
288 __set_current_state(TASK_RUNNING
);
290 poll_freewait(&table
);
296 * We can actually return ERESTARTSYS instead of EINTR, but I'd
297 * like to be certain this leads to no problems. So I return
298 * EINTR just for safety.
300 * Update: ERESTARTSYS breaks at least the xview clock binary, so
301 * I'm trying ERESTARTNOHAND which restart only when you want to.
303 #define MAX_SELECT_SECONDS \
304 ((unsigned long) (MAX_SCHEDULE_TIMEOUT / HZ)-1)
306 static int core_sys_select(int n
, fd_set __user
*inp
, fd_set __user
*outp
,
307 fd_set __user
*exp
, s64
*timeout
)
314 /* Allocate small arguments on the stack to save memory and be faster */
315 long stack_fds
[SELECT_STACK_ALLOC
/sizeof(long)];
321 /* max_fds can increase, so grab it once to avoid race */
323 fdt
= files_fdtable(current
->files
);
324 max_fds
= fdt
->max_fds
;
330 * We need 6 bitmaps (in/out/ex for both incoming and outgoing),
331 * since we used fdset we need to allocate memory in units of
336 if (size
> sizeof(stack_fds
) / 6) {
337 /* Not enough space in on-stack array; must use kmalloc */
339 bits
= kmalloc(6 * size
, GFP_KERNEL
);
344 fds
.out
= bits
+ size
;
345 fds
.ex
= bits
+ 2*size
;
346 fds
.res_in
= bits
+ 3*size
;
347 fds
.res_out
= bits
+ 4*size
;
348 fds
.res_ex
= bits
+ 5*size
;
350 if ((ret
= get_fd_set(n
, inp
, fds
.in
)) ||
351 (ret
= get_fd_set(n
, outp
, fds
.out
)) ||
352 (ret
= get_fd_set(n
, exp
, fds
.ex
)))
354 zero_fd_set(n
, fds
.res_in
);
355 zero_fd_set(n
, fds
.res_out
);
356 zero_fd_set(n
, fds
.res_ex
);
358 ret
= do_select(n
, &fds
, timeout
);
363 ret
= -ERESTARTNOHAND
;
364 if (signal_pending(current
))
369 if (set_fd_set(n
, inp
, fds
.res_in
) ||
370 set_fd_set(n
, outp
, fds
.res_out
) ||
371 set_fd_set(n
, exp
, fds
.res_ex
))
375 if (bits
!= stack_fds
)
381 asmlinkage
long sys_select(int n
, fd_set __user
*inp
, fd_set __user
*outp
,
382 fd_set __user
*exp
, struct timeval __user
*tvp
)
389 if (copy_from_user(&tv
, tvp
, sizeof(tv
)))
392 if (tv
.tv_sec
< 0 || tv
.tv_usec
< 0)
395 /* Cast to u64 to make GCC stop complaining */
396 if ((u64
)tv
.tv_sec
>= (u64
)MAX_INT64_SECONDS
)
397 timeout
= -1; /* infinite */
399 timeout
= DIV_ROUND_UP(tv
.tv_usec
, USEC_PER_SEC
/HZ
);
400 timeout
+= tv
.tv_sec
* HZ
;
404 ret
= core_sys_select(n
, inp
, outp
, exp
, &timeout
);
409 if (current
->personality
& STICKY_TIMEOUTS
)
411 rtv
.tv_usec
= jiffies_to_usecs(do_div((*(u64
*)&timeout
), HZ
));
412 rtv
.tv_sec
= timeout
;
413 if (timeval_compare(&rtv
, &tv
) >= 0)
415 if (copy_to_user(tvp
, &rtv
, sizeof(rtv
))) {
418 * If an application puts its timeval in read-only
419 * memory, we don't want the Linux-specific update to
420 * the timeval to cause a fault after the select has
421 * completed successfully. However, because we're not
422 * updating the timeval, we can't restart the system
425 if (ret
== -ERESTARTNOHAND
)
433 #ifdef TIF_RESTORE_SIGMASK
434 asmlinkage
long sys_pselect7(int n
, fd_set __user
*inp
, fd_set __user
*outp
,
435 fd_set __user
*exp
, struct timespec __user
*tsp
,
436 const sigset_t __user
*sigmask
, size_t sigsetsize
)
438 s64 timeout
= MAX_SCHEDULE_TIMEOUT
;
439 sigset_t ksigmask
, sigsaved
;
444 if (copy_from_user(&ts
, tsp
, sizeof(ts
)))
447 if (ts
.tv_sec
< 0 || ts
.tv_nsec
< 0)
450 /* Cast to u64 to make GCC stop complaining */
451 if ((u64
)ts
.tv_sec
>= (u64
)MAX_INT64_SECONDS
)
452 timeout
= -1; /* infinite */
454 timeout
= DIV_ROUND_UP(ts
.tv_nsec
, NSEC_PER_SEC
/HZ
);
455 timeout
+= ts
.tv_sec
* HZ
;
460 /* XXX: Don't preclude handling different sized sigset_t's. */
461 if (sigsetsize
!= sizeof(sigset_t
))
463 if (copy_from_user(&ksigmask
, sigmask
, sizeof(ksigmask
)))
466 sigdelsetmask(&ksigmask
, sigmask(SIGKILL
)|sigmask(SIGSTOP
));
467 sigprocmask(SIG_SETMASK
, &ksigmask
, &sigsaved
);
470 ret
= core_sys_select(n
, inp
, outp
, exp
, &timeout
);
475 if (current
->personality
& STICKY_TIMEOUTS
)
477 rts
.tv_nsec
= jiffies_to_usecs(do_div((*(u64
*)&timeout
), HZ
)) *
479 rts
.tv_sec
= timeout
;
480 if (timespec_compare(&rts
, &ts
) >= 0)
482 if (copy_to_user(tsp
, &rts
, sizeof(rts
))) {
485 * If an application puts its timeval in read-only
486 * memory, we don't want the Linux-specific update to
487 * the timeval to cause a fault after the select has
488 * completed successfully. However, because we're not
489 * updating the timeval, we can't restart the system
492 if (ret
== -ERESTARTNOHAND
)
497 if (ret
== -ERESTARTNOHAND
) {
499 * Don't restore the signal mask yet. Let do_signal() deliver
500 * the signal on the way back to userspace, before the signal
504 memcpy(¤t
->saved_sigmask
, &sigsaved
,
506 set_thread_flag(TIF_RESTORE_SIGMASK
);
509 sigprocmask(SIG_SETMASK
, &sigsaved
, NULL
);
515 * Most architectures can't handle 7-argument syscalls. So we provide a
516 * 6-argument version where the sixth argument is a pointer to a structure
517 * which has a pointer to the sigset_t itself followed by a size_t containing
520 asmlinkage
long sys_pselect6(int n
, fd_set __user
*inp
, fd_set __user
*outp
,
521 fd_set __user
*exp
, struct timespec __user
*tsp
, void __user
*sig
)
523 size_t sigsetsize
= 0;
524 sigset_t __user
*up
= NULL
;
527 if (!access_ok(VERIFY_READ
, sig
, sizeof(void *)+sizeof(size_t))
528 || __get_user(up
, (sigset_t __user
* __user
*)sig
)
529 || __get_user(sigsetsize
,
530 (size_t __user
*)(sig
+sizeof(void *))))
534 return sys_pselect7(n
, inp
, outp
, exp
, tsp
, up
, sigsetsize
);
536 #endif /* TIF_RESTORE_SIGMASK */
539 struct poll_list
*next
;
541 struct pollfd entries
[0];
544 #define POLLFD_PER_PAGE ((PAGE_SIZE-sizeof(struct poll_list)) / sizeof(struct pollfd))
547 * Fish for pollable events on the pollfd->fd file descriptor. We're only
548 * interested in events matching the pollfd->events mask, and the result
549 * matching that mask is both recorded in pollfd->revents and returned. The
550 * pwait poll_table will be used by the fd-provided poll handler for waiting,
553 static inline unsigned int do_pollfd(struct pollfd
*pollfd
, poll_table
*pwait
)
564 file
= fget_light(fd
, &fput_needed
);
567 mask
= DEFAULT_POLLMASK
;
568 if (file
->f_op
&& file
->f_op
->poll
)
569 mask
= file
->f_op
->poll(file
, pwait
);
570 /* Mask out unneeded events. */
571 mask
&= pollfd
->events
| POLLERR
| POLLHUP
;
572 fput_light(file
, fput_needed
);
575 pollfd
->revents
= mask
;
580 static int do_poll(unsigned int nfds
, struct poll_list
*list
,
581 struct poll_wqueues
*wait
, s64
*timeout
)
584 poll_table
* pt
= &wait
->pt
;
586 /* Optimise the no-wait case */
591 struct poll_list
*walk
;
594 set_current_state(TASK_INTERRUPTIBLE
);
595 for (walk
= list
; walk
!= NULL
; walk
= walk
->next
) {
596 struct pollfd
* pfd
, * pfd_end
;
599 pfd_end
= pfd
+ walk
->len
;
600 for (; pfd
!= pfd_end
; pfd
++) {
602 * Fish for events. If we found one, record it
603 * and kill the poll_table, so we don't
604 * needlessly register any other waiters after
605 * this. They'll get immediately deregistered
606 * when we break out and return.
608 if (do_pollfd(pfd
, pt
)) {
615 * All waiters have already been registered, so don't provide
616 * a poll_table to them on the next loop iteration.
619 if (count
|| !*timeout
|| signal_pending(current
))
626 /* Wait indefinitely */
627 __timeout
= MAX_SCHEDULE_TIMEOUT
;
628 } else if (unlikely(*timeout
>= (s64
)MAX_SCHEDULE_TIMEOUT
-1)) {
630 * Wait for longer than MAX_SCHEDULE_TIMEOUT. Do it in
633 __timeout
= MAX_SCHEDULE_TIMEOUT
- 1;
634 *timeout
-= __timeout
;
636 __timeout
= *timeout
;
640 __timeout
= schedule_timeout(__timeout
);
642 *timeout
+= __timeout
;
644 __set_current_state(TASK_RUNNING
);
648 #define N_STACK_PPS ((sizeof(stack_pps) - sizeof(struct poll_list)) / \
649 sizeof(struct pollfd))
651 int do_sys_poll(struct pollfd __user
*ufds
, unsigned int nfds
, s64
*timeout
)
653 struct poll_wqueues table
;
656 struct poll_list
*head
;
657 struct poll_list
*walk
;
658 /* Allocate small arguments on the stack to save memory and be
659 faster - use long to make sure the buffer is aligned properly
660 on 64 bit archs to avoid unaligned access */
661 long stack_pps
[POLL_STACK_ALLOC
/sizeof(long)];
662 struct poll_list
*stack_pp
= NULL
;
664 /* Do a sanity check on nfds ... */
665 if (nfds
> current
->signal
->rlim
[RLIMIT_NOFILE
].rlim_cur
)
668 poll_initwait(&table
);
675 struct poll_list
*pp
;
677 if (stack_pp
== NULL
)
680 num
= POLLFD_PER_PAGE
;
683 size
= sizeof(struct poll_list
) + sizeof(struct pollfd
)*num
;
685 stack_pp
= pp
= (struct poll_list
*)stack_pps
;
687 pp
= kmalloc(size
, GFP_KERNEL
);
699 if (copy_from_user(pp
->entries
, ufds
+ nfds
-i
,
700 sizeof(struct pollfd
)*num
)) {
707 fdcount
= do_poll(nfds
, head
, &table
, timeout
);
709 /* OK, now copy the revents fields back to user space. */
712 while(walk
!= NULL
) {
713 struct pollfd
*fds
= walk
->entries
;
716 for (j
=0; j
< walk
->len
; j
++, ufds
++) {
717 if(__put_user(fds
[j
].revents
, &ufds
->revents
))
723 if (!fdcount
&& signal_pending(current
))
728 struct poll_list
*pp
= walk
->next
;
729 if (walk
!= stack_pp
)
733 poll_freewait(&table
);
737 asmlinkage
long sys_poll(struct pollfd __user
*ufds
, unsigned int nfds
,
742 if (timeout_msecs
> 0) {
744 /* We can only overflow if HZ > 1000 */
745 if (timeout_msecs
/ 1000 > (s64
)0x7fffffffffffffffULL
/ (s64
)HZ
)
746 timeout_jiffies
= -1;
749 timeout_jiffies
= msecs_to_jiffies(timeout_msecs
);
751 /* Infinite (< 0) or no (0) timeout */
752 timeout_jiffies
= timeout_msecs
;
755 return do_sys_poll(ufds
, nfds
, &timeout_jiffies
);
758 #ifdef TIF_RESTORE_SIGMASK
759 asmlinkage
long sys_ppoll(struct pollfd __user
*ufds
, unsigned int nfds
,
760 struct timespec __user
*tsp
, const sigset_t __user
*sigmask
,
763 sigset_t ksigmask
, sigsaved
;
769 if (copy_from_user(&ts
, tsp
, sizeof(ts
)))
772 /* Cast to u64 to make GCC stop complaining */
773 if ((u64
)ts
.tv_sec
>= (u64
)MAX_INT64_SECONDS
)
774 timeout
= -1; /* infinite */
776 timeout
= DIV_ROUND_UP(ts
.tv_nsec
, NSEC_PER_SEC
/HZ
);
777 timeout
+= ts
.tv_sec
* HZ
;
782 /* XXX: Don't preclude handling different sized sigset_t's. */
783 if (sigsetsize
!= sizeof(sigset_t
))
785 if (copy_from_user(&ksigmask
, sigmask
, sizeof(ksigmask
)))
788 sigdelsetmask(&ksigmask
, sigmask(SIGKILL
)|sigmask(SIGSTOP
));
789 sigprocmask(SIG_SETMASK
, &ksigmask
, &sigsaved
);
792 ret
= do_sys_poll(ufds
, nfds
, &timeout
);
794 /* We can restart this syscall, usually */
797 * Don't restore the signal mask yet. Let do_signal() deliver
798 * the signal on the way back to userspace, before the signal
802 memcpy(¤t
->saved_sigmask
, &sigsaved
,
804 set_thread_flag(TIF_RESTORE_SIGMASK
);
806 ret
= -ERESTARTNOHAND
;
808 sigprocmask(SIG_SETMASK
, &sigsaved
, NULL
);
810 if (tsp
&& timeout
>= 0) {
813 if (current
->personality
& STICKY_TIMEOUTS
)
815 /* Yes, we know it's actually an s64, but it's also positive. */
816 rts
.tv_nsec
= jiffies_to_usecs(do_div((*(u64
*)&timeout
), HZ
)) *
818 rts
.tv_sec
= timeout
;
819 if (timespec_compare(&rts
, &ts
) >= 0)
821 if (copy_to_user(tsp
, &rts
, sizeof(rts
))) {
824 * If an application puts its timeval in read-only
825 * memory, we don't want the Linux-specific update to
826 * the timeval to cause a fault after the select has
827 * completed successfully. However, because we're not
828 * updating the timeval, we can't restart the system
831 if (ret
== -ERESTARTNOHAND
&& timeout
>= 0)
838 #endif /* TIF_RESTORE_SIGMASK */