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/syscalls.h>
18 #include <linux/module.h>
19 #include <linux/slab.h>
20 #include <linux/smp_lock.h>
21 #include <linux/poll.h>
22 #include <linux/personality.h> /* for STICKY_TIMEOUTS */
23 #include <linux/file.h>
26 #include <asm/uaccess.h>
28 #define ROUND_UP(x,y) (((x)+(y)-1)/(y))
29 #define DEFAULT_POLLMASK (POLLIN | POLLOUT | POLLRDNORM | POLLWRNORM)
31 struct poll_table_entry
{
34 wait_queue_head_t
* wait_address
;
37 struct poll_table_page
{
38 struct poll_table_page
* next
;
39 struct poll_table_entry
* entry
;
40 struct poll_table_entry entries
[0];
43 #define POLL_TABLE_FULL(table) \
44 ((unsigned long)((table)->entry+1) > PAGE_SIZE + (unsigned long)(table))
47 * Ok, Peter made a complicated, but straightforward multiple_wait() function.
48 * I have rewritten this, taking some shortcuts: This code may not be easy to
49 * follow, but it should be free of race-conditions, and it's practical. If you
50 * understand what I'm doing here, then you understand how the linux
51 * sleep/wakeup mechanism works.
53 * Two very simple procedures, poll_wait() and poll_freewait() make all the
54 * work. poll_wait() is an inline-function defined in <linux/poll.h>,
55 * as all select/poll functions have to call it to add an entry to the
58 static void __pollwait(struct file
*filp
, wait_queue_head_t
*wait_address
,
61 void poll_initwait(struct poll_wqueues
*pwq
)
63 init_poll_funcptr(&pwq
->pt
, __pollwait
);
68 EXPORT_SYMBOL(poll_initwait
);
70 void poll_freewait(struct poll_wqueues
*pwq
)
72 struct poll_table_page
* p
= pwq
->table
;
74 struct poll_table_entry
* entry
;
75 struct poll_table_page
*old
;
80 remove_wait_queue(entry
->wait_address
,&entry
->wait
);
82 } while (entry
> p
->entries
);
85 free_page((unsigned long) old
);
89 EXPORT_SYMBOL(poll_freewait
);
91 static void __pollwait(struct file
*filp
, wait_queue_head_t
*wait_address
,
94 struct poll_wqueues
*p
= container_of(_p
, struct poll_wqueues
, pt
);
95 struct poll_table_page
*table
= p
->table
;
97 if (!table
|| POLL_TABLE_FULL(table
)) {
98 struct poll_table_page
*new_table
;
100 new_table
= (struct poll_table_page
*) __get_free_page(GFP_KERNEL
);
103 __set_current_state(TASK_RUNNING
);
106 new_table
->entry
= new_table
->entries
;
107 new_table
->next
= table
;
108 p
->table
= new_table
;
112 /* Add a new entry */
114 struct poll_table_entry
* entry
= table
->entry
;
115 table
->entry
= entry
+1;
118 entry
->wait_address
= wait_address
;
119 init_waitqueue_entry(&entry
->wait
, current
);
120 add_wait_queue(wait_address
,&entry
->wait
);
124 #define FDS_IN(fds, n) (fds->in + n)
125 #define FDS_OUT(fds, n) (fds->out + n)
126 #define FDS_EX(fds, n) (fds->ex + n)
128 #define BITS(fds, n) (*FDS_IN(fds, n)|*FDS_OUT(fds, n)|*FDS_EX(fds, n))
130 static int max_select_fd(unsigned long n
, fd_set_bits
*fds
)
132 unsigned long *open_fds
;
137 /* handle last in-complete long-word first */
138 set
= ~(~0UL << (n
& (__NFDBITS
-1)));
140 fdt
= files_fdtable(current
->files
);
141 open_fds
= fdt
->open_fds
->fds_bits
+n
;
146 if (!(set
& ~*open_fds
))
157 if (set
& ~*open_fds
)
166 max
+= n
* __NFDBITS
;
172 #define BIT(i) (1UL << ((i)&(__NFDBITS-1)))
173 #define MEM(i,m) ((m)+(unsigned)(i)/__NFDBITS)
174 #define ISSET(i,m) (((i)&*(m)) != 0)
175 #define SET(i,m) (*(m) |= (i))
177 #define POLLIN_SET (POLLRDNORM | POLLRDBAND | POLLIN | POLLHUP | POLLERR)
178 #define POLLOUT_SET (POLLWRBAND | POLLWRNORM | POLLOUT | POLLERR)
179 #define POLLEX_SET (POLLPRI)
181 int do_select(int n
, fd_set_bits
*fds
, long *timeout
)
183 struct poll_wqueues table
;
186 long __timeout
= *timeout
;
188 spin_lock(¤t
->files
->file_lock
);
189 retval
= max_select_fd(n
, fds
);
190 spin_unlock(¤t
->files
->file_lock
);
196 poll_initwait(&table
);
202 unsigned long *rinp
, *routp
, *rexp
, *inp
, *outp
, *exp
;
204 set_current_state(TASK_INTERRUPTIBLE
);
206 inp
= fds
->in
; outp
= fds
->out
; exp
= fds
->ex
;
207 rinp
= fds
->res_in
; routp
= fds
->res_out
; rexp
= fds
->res_ex
;
209 for (i
= 0; i
< n
; ++rinp
, ++routp
, ++rexp
) {
210 unsigned long in
, out
, ex
, all_bits
, bit
= 1, mask
, j
;
211 unsigned long res_in
= 0, res_out
= 0, res_ex
= 0;
212 struct file_operations
*f_op
= NULL
;
213 struct file
*file
= NULL
;
215 in
= *inp
++; out
= *outp
++; ex
= *exp
++;
216 all_bits
= in
| out
| ex
;
222 for (j
= 0; j
< __NFDBITS
; ++j
, ++i
, bit
<<= 1) {
225 if (!(bit
& all_bits
))
230 mask
= DEFAULT_POLLMASK
;
231 if (f_op
&& f_op
->poll
)
232 mask
= (*f_op
->poll
)(file
, retval
? NULL
: wait
);
234 if ((mask
& POLLIN_SET
) && (in
& bit
)) {
238 if ((mask
& POLLOUT_SET
) && (out
& bit
)) {
242 if ((mask
& POLLEX_SET
) && (ex
& bit
)) {
257 if (retval
|| !__timeout
|| signal_pending(current
))
260 retval
= table
.error
;
263 __timeout
= schedule_timeout(__timeout
);
265 __set_current_state(TASK_RUNNING
);
267 poll_freewait(&table
);
270 * Up-to-date the caller timeout.
272 *timeout
= __timeout
;
276 static void *select_bits_alloc(int size
)
278 return kmalloc(6 * size
, GFP_KERNEL
);
281 static void select_bits_free(void *bits
, int size
)
287 * We can actually return ERESTARTSYS instead of EINTR, but I'd
288 * like to be certain this leads to no problems. So I return
289 * EINTR just for safety.
291 * Update: ERESTARTSYS breaks at least the xview clock binary, so
292 * I'm trying ERESTARTNOHAND which restart only when you want to.
294 #define MAX_SELECT_SECONDS \
295 ((unsigned long) (MAX_SCHEDULE_TIMEOUT / HZ)-1)
298 sys_select(int n
, fd_set __user
*inp
, fd_set __user
*outp
, fd_set __user
*exp
, struct timeval __user
*tvp
)
303 int ret
, size
, max_fdset
;
306 timeout
= MAX_SCHEDULE_TIMEOUT
;
310 if (!access_ok(VERIFY_READ
, tvp
, sizeof(*tvp
))
311 || __get_user(sec
, &tvp
->tv_sec
)
312 || __get_user(usec
, &tvp
->tv_usec
)) {
318 if (sec
< 0 || usec
< 0)
321 if ((unsigned long) sec
< MAX_SELECT_SECONDS
) {
322 timeout
= ROUND_UP(usec
, 1000000/HZ
);
323 timeout
+= sec
* (unsigned long) HZ
;
331 /* max_fdset can increase, so grab it once to avoid race */
332 fdt
= files_fdtable(current
->files
);
333 max_fdset
= fdt
->max_fdset
;
338 * We need 6 bitmaps (in/out/ex for both incoming and outgoing),
339 * since we used fdset we need to allocate memory in units of
344 bits
= select_bits_alloc(size
);
347 fds
.in
= (unsigned long *) bits
;
348 fds
.out
= (unsigned long *) (bits
+ size
);
349 fds
.ex
= (unsigned long *) (bits
+ 2*size
);
350 fds
.res_in
= (unsigned long *) (bits
+ 3*size
);
351 fds
.res_out
= (unsigned long *) (bits
+ 4*size
);
352 fds
.res_ex
= (unsigned long *) (bits
+ 5*size
);
354 if ((ret
= get_fd_set(n
, inp
, fds
.in
)) ||
355 (ret
= get_fd_set(n
, outp
, fds
.out
)) ||
356 (ret
= get_fd_set(n
, exp
, fds
.ex
)))
358 zero_fd_set(n
, fds
.res_in
);
359 zero_fd_set(n
, fds
.res_out
);
360 zero_fd_set(n
, fds
.res_ex
);
362 ret
= do_select(n
, &fds
, &timeout
);
364 if (tvp
&& !(current
->personality
& STICKY_TIMEOUTS
)) {
365 time_t sec
= 0, usec
= 0;
369 usec
*= (1000000/HZ
);
371 put_user(sec
, &tvp
->tv_sec
);
372 put_user(usec
, &tvp
->tv_usec
);
378 ret
= -ERESTARTNOHAND
;
379 if (signal_pending(current
))
384 if (set_fd_set(n
, inp
, fds
.res_in
) ||
385 set_fd_set(n
, outp
, fds
.res_out
) ||
386 set_fd_set(n
, exp
, fds
.res_ex
))
390 select_bits_free(bits
, size
);
396 struct poll_list
*next
;
398 struct pollfd entries
[0];
401 #define POLLFD_PER_PAGE ((PAGE_SIZE-sizeof(struct poll_list)) / sizeof(struct pollfd))
403 static void do_pollfd(unsigned int num
, struct pollfd
* fdpage
,
404 poll_table
** pwait
, int *count
)
408 for (i
= 0; i
< num
; i
++) {
417 struct file
* file
= fget(fd
);
420 mask
= DEFAULT_POLLMASK
;
421 if (file
->f_op
&& file
->f_op
->poll
)
422 mask
= file
->f_op
->poll(file
, *pwait
);
423 mask
&= fdp
->events
| POLLERR
| POLLHUP
;
435 static int do_poll(unsigned int nfds
, struct poll_list
*list
,
436 struct poll_wqueues
*wait
, long timeout
)
439 poll_table
* pt
= &wait
->pt
;
445 struct poll_list
*walk
;
446 set_current_state(TASK_INTERRUPTIBLE
);
448 while(walk
!= NULL
) {
449 do_pollfd( walk
->len
, walk
->entries
, &pt
, &count
);
453 if (count
|| !timeout
|| signal_pending(current
))
458 timeout
= schedule_timeout(timeout
);
460 __set_current_state(TASK_RUNNING
);
464 asmlinkage
long sys_poll(struct pollfd __user
* ufds
, unsigned int nfds
, long timeout
)
466 struct poll_wqueues table
;
469 struct poll_list
*head
;
470 struct poll_list
*walk
;
473 /* Do a sanity check on nfds ... */
474 fdt
= files_fdtable(current
->files
);
475 if (nfds
> fdt
->max_fdset
&& nfds
> OPEN_MAX
)
479 /* Careful about overflow in the intermediate values */
480 if ((unsigned long) timeout
< MAX_SCHEDULE_TIMEOUT
/ HZ
)
481 timeout
= (unsigned long)(timeout
*HZ
+999)/1000+1;
482 else /* Negative or overflow */
483 timeout
= MAX_SCHEDULE_TIMEOUT
;
486 poll_initwait(&table
);
493 struct poll_list
*pp
;
494 pp
= kmalloc(sizeof(struct poll_list
)+
495 sizeof(struct pollfd
)*
496 (i
>POLLFD_PER_PAGE
?POLLFD_PER_PAGE
:i
),
501 pp
->len
= (i
>POLLFD_PER_PAGE
?POLLFD_PER_PAGE
:i
);
508 if (copy_from_user(pp
->entries
, ufds
+ nfds
-i
,
509 sizeof(struct pollfd
)*pp
->len
)) {
515 fdcount
= do_poll(nfds
, head
, &table
, timeout
);
517 /* OK, now copy the revents fields back to user space. */
520 while(walk
!= NULL
) {
521 struct pollfd
*fds
= walk
->entries
;
524 for (j
=0; j
< walk
->len
; j
++, ufds
++) {
525 if(__put_user(fds
[j
].revents
, &ufds
->revents
))
531 if (!fdcount
&& signal_pending(current
))
536 struct poll_list
*pp
= walk
->next
;
540 poll_freewait(&table
);
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