blob: 2e56325c73c47933e10be4d695831639c84744a1 [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
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>
24#include <linux/fs.h>
25
26#include <asm/uaccess.h>
27
28#define ROUND_UP(x,y) (((x)+(y)-1)/(y))
29#define DEFAULT_POLLMASK (POLLIN | POLLOUT | POLLRDNORM | POLLWRNORM)
30
31struct poll_table_entry {
32 struct file * filp;
33 wait_queue_t wait;
34 wait_queue_head_t * wait_address;
35};
36
37struct poll_table_page {
38 struct poll_table_page * next;
39 struct poll_table_entry * entry;
40 struct poll_table_entry entries[0];
41};
42
43#define POLL_TABLE_FULL(table) \
44 ((unsigned long)((table)->entry+1) > PAGE_SIZE + (unsigned long)(table))
45
46/*
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.
52 *
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
56 * poll table.
57 */
Adrian Bunk75c96f82005-05-05 16:16:09 -070058static void __pollwait(struct file *filp, wait_queue_head_t *wait_address,
59 poll_table *p);
Linus Torvalds1da177e2005-04-16 15:20:36 -070060
61void poll_initwait(struct poll_wqueues *pwq)
62{
63 init_poll_funcptr(&pwq->pt, __pollwait);
64 pwq->error = 0;
65 pwq->table = NULL;
66}
67
68EXPORT_SYMBOL(poll_initwait);
69
70void poll_freewait(struct poll_wqueues *pwq)
71{
72 struct poll_table_page * p = pwq->table;
73 while (p) {
74 struct poll_table_entry * entry;
75 struct poll_table_page *old;
76
77 entry = p->entry;
78 do {
79 entry--;
80 remove_wait_queue(entry->wait_address,&entry->wait);
81 fput(entry->filp);
82 } while (entry > p->entries);
83 old = p;
84 p = p->next;
85 free_page((unsigned long) old);
86 }
87}
88
89EXPORT_SYMBOL(poll_freewait);
90
Adrian Bunk75c96f82005-05-05 16:16:09 -070091static void __pollwait(struct file *filp, wait_queue_head_t *wait_address,
92 poll_table *_p)
Linus Torvalds1da177e2005-04-16 15:20:36 -070093{
94 struct poll_wqueues *p = container_of(_p, struct poll_wqueues, pt);
95 struct poll_table_page *table = p->table;
96
97 if (!table || POLL_TABLE_FULL(table)) {
98 struct poll_table_page *new_table;
99
100 new_table = (struct poll_table_page *) __get_free_page(GFP_KERNEL);
101 if (!new_table) {
102 p->error = -ENOMEM;
103 __set_current_state(TASK_RUNNING);
104 return;
105 }
106 new_table->entry = new_table->entries;
107 new_table->next = table;
108 p->table = new_table;
109 table = new_table;
110 }
111
112 /* Add a new entry */
113 {
114 struct poll_table_entry * entry = table->entry;
115 table->entry = entry+1;
116 get_file(filp);
117 entry->filp = filp;
118 entry->wait_address = wait_address;
119 init_waitqueue_entry(&entry->wait, current);
120 add_wait_queue(wait_address,&entry->wait);
121 }
122}
123
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)
127
128#define BITS(fds, n) (*FDS_IN(fds, n)|*FDS_OUT(fds, n)|*FDS_EX(fds, n))
129
130static int max_select_fd(unsigned long n, fd_set_bits *fds)
131{
132 unsigned long *open_fds;
133 unsigned long set;
134 int max;
Dipankar Sarmabadf1662005-09-09 13:04:10 -0700135 struct fdtable *fdt;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700136
137 /* handle last in-complete long-word first */
138 set = ~(~0UL << (n & (__NFDBITS-1)));
139 n /= __NFDBITS;
Dipankar Sarmabadf1662005-09-09 13:04:10 -0700140 fdt = files_fdtable(current->files);
141 open_fds = fdt->open_fds->fds_bits+n;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700142 max = 0;
143 if (set) {
144 set &= BITS(fds, n);
145 if (set) {
146 if (!(set & ~*open_fds))
147 goto get_max;
148 return -EBADF;
149 }
150 }
151 while (n) {
152 open_fds--;
153 n--;
154 set = BITS(fds, n);
155 if (!set)
156 continue;
157 if (set & ~*open_fds)
158 return -EBADF;
159 if (max)
160 continue;
161get_max:
162 do {
163 max++;
164 set >>= 1;
165 } while (set);
166 max += n * __NFDBITS;
167 }
168
169 return max;
170}
171
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))
176
177#define POLLIN_SET (POLLRDNORM | POLLRDBAND | POLLIN | POLLHUP | POLLERR)
178#define POLLOUT_SET (POLLWRBAND | POLLWRNORM | POLLOUT | POLLERR)
179#define POLLEX_SET (POLLPRI)
180
181int do_select(int n, fd_set_bits *fds, long *timeout)
182{
183 struct poll_wqueues table;
184 poll_table *wait;
185 int retval, i;
186 long __timeout = *timeout;
187
188 spin_lock(&current->files->file_lock);
189 retval = max_select_fd(n, fds);
190 spin_unlock(&current->files->file_lock);
191
192 if (retval < 0)
193 return retval;
194 n = retval;
195
196 poll_initwait(&table);
197 wait = &table.pt;
198 if (!__timeout)
199 wait = NULL;
200 retval = 0;
201 for (;;) {
202 unsigned long *rinp, *routp, *rexp, *inp, *outp, *exp;
203
204 set_current_state(TASK_INTERRUPTIBLE);
205
206 inp = fds->in; outp = fds->out; exp = fds->ex;
207 rinp = fds->res_in; routp = fds->res_out; rexp = fds->res_ex;
208
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;
214
215 in = *inp++; out = *outp++; ex = *exp++;
216 all_bits = in | out | ex;
217 if (all_bits == 0) {
218 i += __NFDBITS;
219 continue;
220 }
221
222 for (j = 0; j < __NFDBITS; ++j, ++i, bit <<= 1) {
223 if (i >= n)
224 break;
225 if (!(bit & all_bits))
226 continue;
227 file = fget(i);
228 if (file) {
229 f_op = file->f_op;
230 mask = DEFAULT_POLLMASK;
231 if (f_op && f_op->poll)
232 mask = (*f_op->poll)(file, retval ? NULL : wait);
233 fput(file);
234 if ((mask & POLLIN_SET) && (in & bit)) {
235 res_in |= bit;
236 retval++;
237 }
238 if ((mask & POLLOUT_SET) && (out & bit)) {
239 res_out |= bit;
240 retval++;
241 }
242 if ((mask & POLLEX_SET) && (ex & bit)) {
243 res_ex |= bit;
244 retval++;
245 }
246 }
247 cond_resched();
248 }
249 if (res_in)
250 *rinp = res_in;
251 if (res_out)
252 *routp = res_out;
253 if (res_ex)
254 *rexp = res_ex;
255 }
256 wait = NULL;
257 if (retval || !__timeout || signal_pending(current))
258 break;
259 if(table.error) {
260 retval = table.error;
261 break;
262 }
263 __timeout = schedule_timeout(__timeout);
264 }
265 __set_current_state(TASK_RUNNING);
266
267 poll_freewait(&table);
268
269 /*
270 * Up-to-date the caller timeout.
271 */
272 *timeout = __timeout;
273 return retval;
274}
275
276static void *select_bits_alloc(int size)
277{
278 return kmalloc(6 * size, GFP_KERNEL);
279}
280
281static void select_bits_free(void *bits, int size)
282{
283 kfree(bits);
284}
285
286/*
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.
290 *
291 * Update: ERESTARTSYS breaks at least the xview clock binary, so
292 * I'm trying ERESTARTNOHAND which restart only when you want to.
293 */
294#define MAX_SELECT_SECONDS \
295 ((unsigned long) (MAX_SCHEDULE_TIMEOUT / HZ)-1)
296
297asmlinkage long
298sys_select(int n, fd_set __user *inp, fd_set __user *outp, fd_set __user *exp, struct timeval __user *tvp)
299{
300 fd_set_bits fds;
301 char *bits;
302 long timeout;
303 int ret, size, max_fdset;
Dipankar Sarmabadf1662005-09-09 13:04:10 -0700304 struct fdtable *fdt;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700305
306 timeout = MAX_SCHEDULE_TIMEOUT;
307 if (tvp) {
308 time_t sec, usec;
309
310 if (!access_ok(VERIFY_READ, tvp, sizeof(*tvp))
311 || __get_user(sec, &tvp->tv_sec)
312 || __get_user(usec, &tvp->tv_usec)) {
313 ret = -EFAULT;
314 goto out_nofds;
315 }
316
317 ret = -EINVAL;
318 if (sec < 0 || usec < 0)
319 goto out_nofds;
320
321 if ((unsigned long) sec < MAX_SELECT_SECONDS) {
322 timeout = ROUND_UP(usec, 1000000/HZ);
323 timeout += sec * (unsigned long) HZ;
324 }
325 }
326
327 ret = -EINVAL;
328 if (n < 0)
329 goto out_nofds;
330
331 /* max_fdset can increase, so grab it once to avoid race */
Dipankar Sarmabadf1662005-09-09 13:04:10 -0700332 fdt = files_fdtable(current->files);
333 max_fdset = fdt->max_fdset;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700334 if (n > max_fdset)
335 n = max_fdset;
336
337 /*
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
340 * long-words.
341 */
342 ret = -ENOMEM;
343 size = FDS_BYTES(n);
344 bits = select_bits_alloc(size);
345 if (!bits)
346 goto out_nofds;
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);
353
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)))
357 goto out;
358 zero_fd_set(n, fds.res_in);
359 zero_fd_set(n, fds.res_out);
360 zero_fd_set(n, fds.res_ex);
361
362 ret = do_select(n, &fds, &timeout);
363
364 if (tvp && !(current->personality & STICKY_TIMEOUTS)) {
365 time_t sec = 0, usec = 0;
366 if (timeout) {
367 sec = timeout / HZ;
368 usec = timeout % HZ;
369 usec *= (1000000/HZ);
370 }
371 put_user(sec, &tvp->tv_sec);
372 put_user(usec, &tvp->tv_usec);
373 }
374
375 if (ret < 0)
376 goto out;
377 if (!ret) {
378 ret = -ERESTARTNOHAND;
379 if (signal_pending(current))
380 goto out;
381 ret = 0;
382 }
383
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))
387 ret = -EFAULT;
388
389out:
390 select_bits_free(bits, size);
391out_nofds:
392 return ret;
393}
394
395struct poll_list {
396 struct poll_list *next;
397 int len;
398 struct pollfd entries[0];
399};
400
401#define POLLFD_PER_PAGE ((PAGE_SIZE-sizeof(struct poll_list)) / sizeof(struct pollfd))
402
403static void do_pollfd(unsigned int num, struct pollfd * fdpage,
404 poll_table ** pwait, int *count)
405{
406 int i;
407
408 for (i = 0; i < num; i++) {
409 int fd;
410 unsigned int mask;
411 struct pollfd *fdp;
412
413 mask = 0;
414 fdp = fdpage+i;
415 fd = fdp->fd;
416 if (fd >= 0) {
417 struct file * file = fget(fd);
418 mask = POLLNVAL;
419 if (file != NULL) {
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;
424 fput(file);
425 }
426 if (mask) {
427 *pwait = NULL;
428 (*count)++;
429 }
430 }
431 fdp->revents = mask;
432 }
433}
434
435static int do_poll(unsigned int nfds, struct poll_list *list,
436 struct poll_wqueues *wait, long timeout)
437{
438 int count = 0;
439 poll_table* pt = &wait->pt;
440
441 if (!timeout)
442 pt = NULL;
443
444 for (;;) {
445 struct poll_list *walk;
446 set_current_state(TASK_INTERRUPTIBLE);
447 walk = list;
448 while(walk != NULL) {
449 do_pollfd( walk->len, walk->entries, &pt, &count);
450 walk = walk->next;
451 }
452 pt = NULL;
453 if (count || !timeout || signal_pending(current))
454 break;
455 count = wait->error;
456 if (count)
457 break;
458 timeout = schedule_timeout(timeout);
459 }
460 __set_current_state(TASK_RUNNING);
461 return count;
462}
463
464asmlinkage long sys_poll(struct pollfd __user * ufds, unsigned int nfds, long timeout)
465{
466 struct poll_wqueues table;
467 int fdcount, err;
468 unsigned int i;
469 struct poll_list *head;
470 struct poll_list *walk;
Dipankar Sarmabadf1662005-09-09 13:04:10 -0700471 struct fdtable *fdt;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700472
473 /* Do a sanity check on nfds ... */
Dipankar Sarmabadf1662005-09-09 13:04:10 -0700474 fdt = files_fdtable(current->files);
475 if (nfds > fdt->max_fdset && nfds > OPEN_MAX)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700476 return -EINVAL;
477
478 if (timeout) {
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;
484 }
485
486 poll_initwait(&table);
487
488 head = NULL;
489 walk = NULL;
490 i = nfds;
491 err = -ENOMEM;
492 while(i!=0) {
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),
497 GFP_KERNEL);
498 if(pp==NULL)
499 goto out_fds;
500 pp->next=NULL;
501 pp->len = (i>POLLFD_PER_PAGE?POLLFD_PER_PAGE:i);
502 if (head == NULL)
503 head = pp;
504 else
505 walk->next = pp;
506
507 walk = pp;
508 if (copy_from_user(pp->entries, ufds + nfds-i,
509 sizeof(struct pollfd)*pp->len)) {
510 err = -EFAULT;
511 goto out_fds;
512 }
513 i -= pp->len;
514 }
515 fdcount = do_poll(nfds, head, &table, timeout);
516
517 /* OK, now copy the revents fields back to user space. */
518 walk = head;
519 err = -EFAULT;
520 while(walk != NULL) {
521 struct pollfd *fds = walk->entries;
522 int j;
523
524 for (j=0; j < walk->len; j++, ufds++) {
525 if(__put_user(fds[j].revents, &ufds->revents))
526 goto out_fds;
527 }
528 walk = walk->next;
529 }
530 err = fdcount;
531 if (!fdcount && signal_pending(current))
532 err = -EINTR;
533out_fds:
534 walk = head;
535 while(walk!=NULL) {
536 struct poll_list *pp = walk->next;
537 kfree(walk);
538 walk = pp;
539 }
540 poll_freewait(&table);
541 return err;
542}