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Commit | Line | Data |
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1 | /* | |
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/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> | |
24 | #include <linux/fs.h> | |
25 | #include <linux/rcupdate.h> | |
26 | ||
27 | #include <asm/uaccess.h> | |
28 | ||
29 | struct poll_table_page { | |
30 | struct poll_table_page * next; | |
31 | struct poll_table_entry * entry; | |
32 | struct poll_table_entry entries[0]; | |
33 | }; | |
34 | ||
35 | #define POLL_TABLE_FULL(table) \ | |
36 | ((unsigned long)((table)->entry+1) > PAGE_SIZE + (unsigned long)(table)) | |
37 | ||
38 | /* | |
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. | |
44 | * | |
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 | |
48 | * poll table. | |
49 | */ | |
50 | static void __pollwait(struct file *filp, wait_queue_head_t *wait_address, | |
51 | poll_table *p); | |
52 | ||
53 | void poll_initwait(struct poll_wqueues *pwq) | |
54 | { | |
55 | init_poll_funcptr(&pwq->pt, __pollwait); | |
56 | pwq->error = 0; | |
57 | pwq->table = NULL; | |
58 | pwq->inline_index = 0; | |
59 | } | |
60 | ||
61 | EXPORT_SYMBOL(poll_initwait); | |
62 | ||
63 | static void free_poll_entry(struct poll_table_entry *entry) | |
64 | { | |
65 | remove_wait_queue(entry->wait_address, &entry->wait); | |
66 | fput(entry->filp); | |
67 | } | |
68 | ||
69 | void poll_freewait(struct poll_wqueues *pwq) | |
70 | { | |
71 | struct poll_table_page * p = pwq->table; | |
72 | int i; | |
73 | for (i = 0; i < pwq->inline_index; i++) | |
74 | free_poll_entry(pwq->inline_entries + i); | |
75 | while (p) { | |
76 | struct poll_table_entry * entry; | |
77 | struct poll_table_page *old; | |
78 | ||
79 | entry = p->entry; | |
80 | do { | |
81 | entry--; | |
82 | free_poll_entry(entry); | |
83 | } while (entry > p->entries); | |
84 | old = p; | |
85 | p = p->next; | |
86 | free_page((unsigned long) old); | |
87 | } | |
88 | } | |
89 | ||
90 | EXPORT_SYMBOL(poll_freewait); | |
91 | ||
92 | static struct poll_table_entry *poll_get_entry(poll_table *_p) | |
93 | { | |
94 | struct poll_wqueues *p = container_of(_p, struct poll_wqueues, pt); | |
95 | struct poll_table_page *table = p->table; | |
96 | ||
97 | if (p->inline_index < N_INLINE_POLL_ENTRIES) | |
98 | return p->inline_entries + p->inline_index++; | |
99 | ||
100 | if (!table || POLL_TABLE_FULL(table)) { | |
101 | struct poll_table_page *new_table; | |
102 | ||
103 | new_table = (struct poll_table_page *) __get_free_page(GFP_KERNEL); | |
104 | if (!new_table) { | |
105 | p->error = -ENOMEM; | |
106 | __set_current_state(TASK_RUNNING); | |
107 | return NULL; | |
108 | } | |
109 | new_table->entry = new_table->entries; | |
110 | new_table->next = table; | |
111 | p->table = new_table; | |
112 | table = new_table; | |
113 | } | |
114 | ||
115 | return table->entry++; | |
116 | } | |
117 | ||
118 | /* Add a new entry */ | |
119 | static void __pollwait(struct file *filp, wait_queue_head_t *wait_address, | |
120 | poll_table *p) | |
121 | { | |
122 | struct poll_table_entry *entry = poll_get_entry(p); | |
123 | if (!entry) | |
124 | return; | |
125 | get_file(filp); | |
126 | entry->filp = filp; | |
127 | entry->wait_address = wait_address; | |
128 | init_waitqueue_entry(&entry->wait, current); | |
129 | add_wait_queue(wait_address, &entry->wait); | |
130 | } | |
131 | ||
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) | |
135 | ||
136 | #define BITS(fds, n) (*FDS_IN(fds, n)|*FDS_OUT(fds, n)|*FDS_EX(fds, n)) | |
137 | ||
138 | static int max_select_fd(unsigned long n, fd_set_bits *fds) | |
139 | { | |
140 | unsigned long *open_fds; | |
141 | unsigned long set; | |
142 | int max; | |
143 | struct fdtable *fdt; | |
144 | ||
145 | /* handle last in-complete long-word first */ | |
146 | set = ~(~0UL << (n & (__NFDBITS-1))); | |
147 | n /= __NFDBITS; | |
148 | fdt = files_fdtable(current->files); | |
149 | open_fds = fdt->open_fds->fds_bits+n; | |
150 | max = 0; | |
151 | if (set) { | |
152 | set &= BITS(fds, n); | |
153 | if (set) { | |
154 | if (!(set & ~*open_fds)) | |
155 | goto get_max; | |
156 | return -EBADF; | |
157 | } | |
158 | } | |
159 | while (n) { | |
160 | open_fds--; | |
161 | n--; | |
162 | set = BITS(fds, n); | |
163 | if (!set) | |
164 | continue; | |
165 | if (set & ~*open_fds) | |
166 | return -EBADF; | |
167 | if (max) | |
168 | continue; | |
169 | get_max: | |
170 | do { | |
171 | max++; | |
172 | set >>= 1; | |
173 | } while (set); | |
174 | max += n * __NFDBITS; | |
175 | } | |
176 | ||
177 | return max; | |
178 | } | |
179 | ||
180 | #define POLLIN_SET (POLLRDNORM | POLLRDBAND | POLLIN | POLLHUP | POLLERR) | |
181 | #define POLLOUT_SET (POLLWRBAND | POLLWRNORM | POLLOUT | POLLERR) | |
182 | #define POLLEX_SET (POLLPRI) | |
183 | ||
184 | int do_select(int n, fd_set_bits *fds, s64 *timeout) | |
185 | { | |
186 | struct poll_wqueues table; | |
187 | poll_table *wait; | |
188 | int retval, i; | |
189 | ||
190 | rcu_read_lock(); | |
191 | retval = max_select_fd(n, fds); | |
192 | rcu_read_unlock(); | |
193 | ||
194 | if (retval < 0) | |
195 | return retval; | |
196 | n = retval; | |
197 | ||
198 | poll_initwait(&table); | |
199 | wait = &table.pt; | |
200 | if (!*timeout) | |
201 | wait = NULL; | |
202 | retval = 0; | |
203 | for (;;) { | |
204 | unsigned long *rinp, *routp, *rexp, *inp, *outp, *exp; | |
205 | long __timeout; | |
206 | ||
207 | set_current_state(TASK_INTERRUPTIBLE); | |
208 | ||
209 | inp = fds->in; outp = fds->out; exp = fds->ex; | |
210 | rinp = fds->res_in; routp = fds->res_out; rexp = fds->res_ex; | |
211 | ||
212 | for (i = 0; i < n; ++rinp, ++routp, ++rexp) { | |
213 | unsigned long in, out, ex, all_bits, bit = 1, mask, j; | |
214 | unsigned long res_in = 0, res_out = 0, res_ex = 0; | |
215 | const struct file_operations *f_op = NULL; | |
216 | struct file *file = NULL; | |
217 | ||
218 | in = *inp++; out = *outp++; ex = *exp++; | |
219 | all_bits = in | out | ex; | |
220 | if (all_bits == 0) { | |
221 | i += __NFDBITS; | |
222 | continue; | |
223 | } | |
224 | ||
225 | for (j = 0; j < __NFDBITS; ++j, ++i, bit <<= 1) { | |
226 | int fput_needed; | |
227 | if (i >= n) | |
228 | break; | |
229 | if (!(bit & all_bits)) | |
230 | continue; | |
231 | file = fget_light(i, &fput_needed); | |
232 | if (file) { | |
233 | f_op = file->f_op; | |
234 | mask = DEFAULT_POLLMASK; | |
235 | if (f_op && f_op->poll) | |
236 | mask = (*f_op->poll)(file, retval ? NULL : wait); | |
237 | fput_light(file, fput_needed); | |
238 | if ((mask & POLLIN_SET) && (in & bit)) { | |
239 | res_in |= bit; | |
240 | retval++; | |
241 | } | |
242 | if ((mask & POLLOUT_SET) && (out & bit)) { | |
243 | res_out |= bit; | |
244 | retval++; | |
245 | } | |
246 | if ((mask & POLLEX_SET) && (ex & bit)) { | |
247 | res_ex |= bit; | |
248 | retval++; | |
249 | } | |
250 | } | |
251 | cond_resched(); | |
252 | } | |
253 | if (res_in) | |
254 | *rinp = res_in; | |
255 | if (res_out) | |
256 | *routp = res_out; | |
257 | if (res_ex) | |
258 | *rexp = res_ex; | |
259 | } | |
260 | wait = NULL; | |
261 | if (retval || !*timeout || signal_pending(current)) | |
262 | break; | |
263 | if (table.error) { | |
264 | retval = table.error; | |
265 | break; | |
266 | } | |
267 | ||
268 | if (*timeout < 0) { | |
269 | /* Wait indefinitely */ | |
270 | __timeout = MAX_SCHEDULE_TIMEOUT; | |
271 | } else if (unlikely(*timeout >= (s64)MAX_SCHEDULE_TIMEOUT - 1)) { | |
272 | /* Wait for longer than MAX_SCHEDULE_TIMEOUT. Do it in a loop */ | |
273 | __timeout = MAX_SCHEDULE_TIMEOUT - 1; | |
274 | *timeout -= __timeout; | |
275 | } else { | |
276 | __timeout = *timeout; | |
277 | *timeout = 0; | |
278 | } | |
279 | __timeout = schedule_timeout(__timeout); | |
280 | if (*timeout >= 0) | |
281 | *timeout += __timeout; | |
282 | } | |
283 | __set_current_state(TASK_RUNNING); | |
284 | ||
285 | poll_freewait(&table); | |
286 | ||
287 | return retval; | |
288 | } | |
289 | ||
290 | /* | |
291 | * We can actually return ERESTARTSYS instead of EINTR, but I'd | |
292 | * like to be certain this leads to no problems. So I return | |
293 | * EINTR just for safety. | |
294 | * | |
295 | * Update: ERESTARTSYS breaks at least the xview clock binary, so | |
296 | * I'm trying ERESTARTNOHAND which restart only when you want to. | |
297 | */ | |
298 | #define MAX_SELECT_SECONDS \ | |
299 | ((unsigned long) (MAX_SCHEDULE_TIMEOUT / HZ)-1) | |
300 | ||
301 | static int core_sys_select(int n, fd_set __user *inp, fd_set __user *outp, | |
302 | fd_set __user *exp, s64 *timeout) | |
303 | { | |
304 | fd_set_bits fds; | |
305 | void *bits; | |
306 | int ret, max_fds; | |
307 | unsigned int size; | |
308 | struct fdtable *fdt; | |
309 | /* Allocate small arguments on the stack to save memory and be faster */ | |
310 | long stack_fds[SELECT_STACK_ALLOC/sizeof(long)]; | |
311 | ||
312 | ret = -EINVAL; | |
313 | if (n < 0) | |
314 | goto out_nofds; | |
315 | ||
316 | /* max_fds can increase, so grab it once to avoid race */ | |
317 | rcu_read_lock(); | |
318 | fdt = files_fdtable(current->files); | |
319 | max_fds = fdt->max_fds; | |
320 | rcu_read_unlock(); | |
321 | if (n > max_fds) | |
322 | n = max_fds; | |
323 | ||
324 | /* | |
325 | * We need 6 bitmaps (in/out/ex for both incoming and outgoing), | |
326 | * since we used fdset we need to allocate memory in units of | |
327 | * long-words. | |
328 | */ | |
329 | size = FDS_BYTES(n); | |
330 | bits = stack_fds; | |
331 | if (size > sizeof(stack_fds) / 6) { | |
332 | /* Not enough space in on-stack array; must use kmalloc */ | |
333 | ret = -ENOMEM; | |
334 | bits = kmalloc(6 * size, GFP_KERNEL); | |
335 | if (!bits) | |
336 | goto out_nofds; | |
337 | } | |
338 | fds.in = bits; | |
339 | fds.out = bits + size; | |
340 | fds.ex = bits + 2*size; | |
341 | fds.res_in = bits + 3*size; | |
342 | fds.res_out = bits + 4*size; | |
343 | fds.res_ex = bits + 5*size; | |
344 | ||
345 | if ((ret = get_fd_set(n, inp, fds.in)) || | |
346 | (ret = get_fd_set(n, outp, fds.out)) || | |
347 | (ret = get_fd_set(n, exp, fds.ex))) | |
348 | goto out; | |
349 | zero_fd_set(n, fds.res_in); | |
350 | zero_fd_set(n, fds.res_out); | |
351 | zero_fd_set(n, fds.res_ex); | |
352 | ||
353 | ret = do_select(n, &fds, timeout); | |
354 | ||
355 | if (ret < 0) | |
356 | goto out; | |
357 | if (!ret) { | |
358 | ret = -ERESTARTNOHAND; | |
359 | if (signal_pending(current)) | |
360 | goto out; | |
361 | ret = 0; | |
362 | } | |
363 | ||
364 | if (set_fd_set(n, inp, fds.res_in) || | |
365 | set_fd_set(n, outp, fds.res_out) || | |
366 | set_fd_set(n, exp, fds.res_ex)) | |
367 | ret = -EFAULT; | |
368 | ||
369 | out: | |
370 | if (bits != stack_fds) | |
371 | kfree(bits); | |
372 | out_nofds: | |
373 | return ret; | |
374 | } | |
375 | ||
376 | asmlinkage long sys_select(int n, fd_set __user *inp, fd_set __user *outp, | |
377 | fd_set __user *exp, struct timeval __user *tvp) | |
378 | { | |
379 | s64 timeout = -1; | |
380 | struct timeval tv; | |
381 | int ret; | |
382 | ||
383 | if (tvp) { | |
384 | if (copy_from_user(&tv, tvp, sizeof(tv))) | |
385 | return -EFAULT; | |
386 | ||
387 | if (tv.tv_sec < 0 || tv.tv_usec < 0) | |
388 | return -EINVAL; | |
389 | ||
390 | /* Cast to u64 to make GCC stop complaining */ | |
391 | if ((u64)tv.tv_sec >= (u64)MAX_INT64_SECONDS) | |
392 | timeout = -1; /* infinite */ | |
393 | else { | |
394 | timeout = DIV_ROUND_UP(tv.tv_usec, USEC_PER_SEC/HZ); | |
395 | timeout += tv.tv_sec * HZ; | |
396 | } | |
397 | } | |
398 | ||
399 | ret = core_sys_select(n, inp, outp, exp, &timeout); | |
400 | ||
401 | if (tvp) { | |
402 | struct timeval rtv; | |
403 | ||
404 | if (current->personality & STICKY_TIMEOUTS) | |
405 | goto sticky; | |
406 | rtv.tv_usec = jiffies_to_usecs(do_div((*(u64*)&timeout), HZ)); | |
407 | rtv.tv_sec = timeout; | |
408 | if (timeval_compare(&rtv, &tv) >= 0) | |
409 | rtv = tv; | |
410 | if (copy_to_user(tvp, &rtv, sizeof(rtv))) { | |
411 | sticky: | |
412 | /* | |
413 | * If an application puts its timeval in read-only | |
414 | * memory, we don't want the Linux-specific update to | |
415 | * the timeval to cause a fault after the select has | |
416 | * completed successfully. However, because we're not | |
417 | * updating the timeval, we can't restart the system | |
418 | * call. | |
419 | */ | |
420 | if (ret == -ERESTARTNOHAND) | |
421 | ret = -EINTR; | |
422 | } | |
423 | } | |
424 | ||
425 | return ret; | |
426 | } | |
427 | ||
428 | #ifdef TIF_RESTORE_SIGMASK | |
429 | asmlinkage long sys_pselect7(int n, fd_set __user *inp, fd_set __user *outp, | |
430 | fd_set __user *exp, struct timespec __user *tsp, | |
431 | const sigset_t __user *sigmask, size_t sigsetsize) | |
432 | { | |
433 | s64 timeout = MAX_SCHEDULE_TIMEOUT; | |
434 | sigset_t ksigmask, sigsaved; | |
435 | struct timespec ts; | |
436 | int ret; | |
437 | ||
438 | if (tsp) { | |
439 | if (copy_from_user(&ts, tsp, sizeof(ts))) | |
440 | return -EFAULT; | |
441 | ||
442 | if (ts.tv_sec < 0 || ts.tv_nsec < 0) | |
443 | return -EINVAL; | |
444 | ||
445 | /* Cast to u64 to make GCC stop complaining */ | |
446 | if ((u64)ts.tv_sec >= (u64)MAX_INT64_SECONDS) | |
447 | timeout = -1; /* infinite */ | |
448 | else { | |
449 | timeout = DIV_ROUND_UP(ts.tv_nsec, NSEC_PER_SEC/HZ); | |
450 | timeout += ts.tv_sec * HZ; | |
451 | } | |
452 | } | |
453 | ||
454 | if (sigmask) { | |
455 | /* XXX: Don't preclude handling different sized sigset_t's. */ | |
456 | if (sigsetsize != sizeof(sigset_t)) | |
457 | return -EINVAL; | |
458 | if (copy_from_user(&ksigmask, sigmask, sizeof(ksigmask))) | |
459 | return -EFAULT; | |
460 | ||
461 | sigdelsetmask(&ksigmask, sigmask(SIGKILL)|sigmask(SIGSTOP)); | |
462 | sigprocmask(SIG_SETMASK, &ksigmask, &sigsaved); | |
463 | } | |
464 | ||
465 | ret = core_sys_select(n, inp, outp, exp, &timeout); | |
466 | ||
467 | if (tsp) { | |
468 | struct timespec rts; | |
469 | ||
470 | if (current->personality & STICKY_TIMEOUTS) | |
471 | goto sticky; | |
472 | rts.tv_nsec = jiffies_to_usecs(do_div((*(u64*)&timeout), HZ)) * | |
473 | 1000; | |
474 | rts.tv_sec = timeout; | |
475 | if (timespec_compare(&rts, &ts) >= 0) | |
476 | rts = ts; | |
477 | if (copy_to_user(tsp, &rts, sizeof(rts))) { | |
478 | sticky: | |
479 | /* | |
480 | * If an application puts its timeval in read-only | |
481 | * memory, we don't want the Linux-specific update to | |
482 | * the timeval to cause a fault after the select has | |
483 | * completed successfully. However, because we're not | |
484 | * updating the timeval, we can't restart the system | |
485 | * call. | |
486 | */ | |
487 | if (ret == -ERESTARTNOHAND) | |
488 | ret = -EINTR; | |
489 | } | |
490 | } | |
491 | ||
492 | if (ret == -ERESTARTNOHAND) { | |
493 | /* | |
494 | * Don't restore the signal mask yet. Let do_signal() deliver | |
495 | * the signal on the way back to userspace, before the signal | |
496 | * mask is restored. | |
497 | */ | |
498 | if (sigmask) { | |
499 | memcpy(¤t->saved_sigmask, &sigsaved, | |
500 | sizeof(sigsaved)); | |
501 | set_thread_flag(TIF_RESTORE_SIGMASK); | |
502 | } | |
503 | } else if (sigmask) | |
504 | sigprocmask(SIG_SETMASK, &sigsaved, NULL); | |
505 | ||
506 | return ret; | |
507 | } | |
508 | ||
509 | /* | |
510 | * Most architectures can't handle 7-argument syscalls. So we provide a | |
511 | * 6-argument version where the sixth argument is a pointer to a structure | |
512 | * which has a pointer to the sigset_t itself followed by a size_t containing | |
513 | * the sigset size. | |
514 | */ | |
515 | asmlinkage long sys_pselect6(int n, fd_set __user *inp, fd_set __user *outp, | |
516 | fd_set __user *exp, struct timespec __user *tsp, void __user *sig) | |
517 | { | |
518 | size_t sigsetsize = 0; | |
519 | sigset_t __user *up = NULL; | |
520 | ||
521 | if (sig) { | |
522 | if (!access_ok(VERIFY_READ, sig, sizeof(void *)+sizeof(size_t)) | |
523 | || __get_user(up, (sigset_t __user * __user *)sig) | |
524 | || __get_user(sigsetsize, | |
525 | (size_t __user *)(sig+sizeof(void *)))) | |
526 | return -EFAULT; | |
527 | } | |
528 | ||
529 | return sys_pselect7(n, inp, outp, exp, tsp, up, sigsetsize); | |
530 | } | |
531 | #endif /* TIF_RESTORE_SIGMASK */ | |
532 | ||
533 | struct poll_list { | |
534 | struct poll_list *next; | |
535 | int len; | |
536 | struct pollfd entries[0]; | |
537 | }; | |
538 | ||
539 | #define POLLFD_PER_PAGE ((PAGE_SIZE-sizeof(struct poll_list)) / sizeof(struct pollfd)) | |
540 | ||
541 | /* | |
542 | * Fish for pollable events on the pollfd->fd file descriptor. We're only | |
543 | * interested in events matching the pollfd->events mask, and the result | |
544 | * matching that mask is both recorded in pollfd->revents and returned. The | |
545 | * pwait poll_table will be used by the fd-provided poll handler for waiting, | |
546 | * if non-NULL. | |
547 | */ | |
548 | static inline unsigned int do_pollfd(struct pollfd *pollfd, poll_table *pwait) | |
549 | { | |
550 | unsigned int mask; | |
551 | int fd; | |
552 | ||
553 | mask = 0; | |
554 | fd = pollfd->fd; | |
555 | if (fd >= 0) { | |
556 | int fput_needed; | |
557 | struct file * file; | |
558 | ||
559 | file = fget_light(fd, &fput_needed); | |
560 | mask = POLLNVAL; | |
561 | if (file != NULL) { | |
562 | mask = DEFAULT_POLLMASK; | |
563 | if (file->f_op && file->f_op->poll) | |
564 | mask = file->f_op->poll(file, pwait); | |
565 | /* Mask out unneeded events. */ | |
566 | mask &= pollfd->events | POLLERR | POLLHUP; | |
567 | fput_light(file, fput_needed); | |
568 | } | |
569 | } | |
570 | pollfd->revents = mask; | |
571 | ||
572 | return mask; | |
573 | } | |
574 | ||
575 | static int do_poll(unsigned int nfds, struct poll_list *list, | |
576 | struct poll_wqueues *wait, s64 *timeout) | |
577 | { | |
578 | int count = 0; | |
579 | poll_table* pt = &wait->pt; | |
580 | ||
581 | /* Optimise the no-wait case */ | |
582 | if (!(*timeout)) | |
583 | pt = NULL; | |
584 | ||
585 | for (;;) { | |
586 | struct poll_list *walk; | |
587 | long __timeout; | |
588 | ||
589 | set_current_state(TASK_INTERRUPTIBLE); | |
590 | for (walk = list; walk != NULL; walk = walk->next) { | |
591 | struct pollfd * pfd, * pfd_end; | |
592 | ||
593 | pfd = walk->entries; | |
594 | pfd_end = pfd + walk->len; | |
595 | for (; pfd != pfd_end; pfd++) { | |
596 | /* | |
597 | * Fish for events. If we found one, record it | |
598 | * and kill the poll_table, so we don't | |
599 | * needlessly register any other waiters after | |
600 | * this. They'll get immediately deregistered | |
601 | * when we break out and return. | |
602 | */ | |
603 | if (do_pollfd(pfd, pt)) { | |
604 | count++; | |
605 | pt = NULL; | |
606 | } | |
607 | } | |
608 | } | |
609 | /* | |
610 | * All waiters have already been registered, so don't provide | |
611 | * a poll_table to them on the next loop iteration. | |
612 | */ | |
613 | pt = NULL; | |
614 | if (!count) { | |
615 | count = wait->error; | |
616 | if (signal_pending(current)) | |
617 | count = -EINTR; | |
618 | } | |
619 | if (count || !*timeout) | |
620 | break; | |
621 | ||
622 | if (*timeout < 0) { | |
623 | /* Wait indefinitely */ | |
624 | __timeout = MAX_SCHEDULE_TIMEOUT; | |
625 | } else if (unlikely(*timeout >= (s64)MAX_SCHEDULE_TIMEOUT-1)) { | |
626 | /* | |
627 | * Wait for longer than MAX_SCHEDULE_TIMEOUT. Do it in | |
628 | * a loop | |
629 | */ | |
630 | __timeout = MAX_SCHEDULE_TIMEOUT - 1; | |
631 | *timeout -= __timeout; | |
632 | } else { | |
633 | __timeout = *timeout; | |
634 | *timeout = 0; | |
635 | } | |
636 | ||
637 | __timeout = schedule_timeout(__timeout); | |
638 | if (*timeout >= 0) | |
639 | *timeout += __timeout; | |
640 | } | |
641 | __set_current_state(TASK_RUNNING); | |
642 | return count; | |
643 | } | |
644 | ||
645 | #define N_STACK_PPS ((sizeof(stack_pps) - sizeof(struct poll_list)) / \ | |
646 | sizeof(struct pollfd)) | |
647 | ||
648 | int do_sys_poll(struct pollfd __user *ufds, unsigned int nfds, s64 *timeout) | |
649 | { | |
650 | struct poll_wqueues table; | |
651 | int err = -EFAULT, fdcount, len, size; | |
652 | /* Allocate small arguments on the stack to save memory and be | |
653 | faster - use long to make sure the buffer is aligned properly | |
654 | on 64 bit archs to avoid unaligned access */ | |
655 | long stack_pps[POLL_STACK_ALLOC/sizeof(long)]; | |
656 | struct poll_list *const head = (struct poll_list *)stack_pps; | |
657 | struct poll_list *walk = head; | |
658 | unsigned long todo = nfds; | |
659 | ||
660 | if (nfds > current->signal->rlim[RLIMIT_NOFILE].rlim_cur) | |
661 | return -EINVAL; | |
662 | ||
663 | len = min_t(unsigned int, nfds, N_STACK_PPS); | |
664 | for (;;) { | |
665 | walk->next = NULL; | |
666 | walk->len = len; | |
667 | if (!len) | |
668 | break; | |
669 | ||
670 | if (copy_from_user(walk->entries, ufds + nfds-todo, | |
671 | sizeof(struct pollfd) * walk->len)) | |
672 | goto out_fds; | |
673 | ||
674 | todo -= walk->len; | |
675 | if (!todo) | |
676 | break; | |
677 | ||
678 | len = min(todo, POLLFD_PER_PAGE); | |
679 | size = sizeof(struct poll_list) + sizeof(struct pollfd) * len; | |
680 | walk = walk->next = kmalloc(size, GFP_KERNEL); | |
681 | if (!walk) { | |
682 | err = -ENOMEM; | |
683 | goto out_fds; | |
684 | } | |
685 | } | |
686 | ||
687 | poll_initwait(&table); | |
688 | fdcount = do_poll(nfds, head, &table, timeout); | |
689 | poll_freewait(&table); | |
690 | ||
691 | for (walk = head; walk; walk = walk->next) { | |
692 | struct pollfd *fds = walk->entries; | |
693 | int j; | |
694 | ||
695 | for (j = 0; j < walk->len; j++, ufds++) | |
696 | if (__put_user(fds[j].revents, &ufds->revents)) | |
697 | goto out_fds; | |
698 | } | |
699 | ||
700 | err = fdcount; | |
701 | out_fds: | |
702 | walk = head->next; | |
703 | while (walk) { | |
704 | struct poll_list *pos = walk; | |
705 | walk = walk->next; | |
706 | kfree(pos); | |
707 | } | |
708 | ||
709 | return err; | |
710 | } | |
711 | ||
712 | static long do_restart_poll(struct restart_block *restart_block) | |
713 | { | |
714 | struct pollfd __user *ufds = (struct pollfd __user*)restart_block->arg0; | |
715 | int nfds = restart_block->arg1; | |
716 | s64 timeout = ((s64)restart_block->arg3<<32) | (s64)restart_block->arg2; | |
717 | int ret; | |
718 | ||
719 | ret = do_sys_poll(ufds, nfds, &timeout); | |
720 | if (ret == -EINTR) { | |
721 | restart_block->fn = do_restart_poll; | |
722 | restart_block->arg2 = timeout & 0xFFFFFFFF; | |
723 | restart_block->arg3 = (u64)timeout >> 32; | |
724 | ret = -ERESTART_RESTARTBLOCK; | |
725 | } | |
726 | return ret; | |
727 | } | |
728 | ||
729 | asmlinkage long sys_poll(struct pollfd __user *ufds, unsigned int nfds, | |
730 | long timeout_msecs) | |
731 | { | |
732 | s64 timeout_jiffies; | |
733 | int ret; | |
734 | ||
735 | if (timeout_msecs > 0) { | |
736 | #if HZ > 1000 | |
737 | /* We can only overflow if HZ > 1000 */ | |
738 | if (timeout_msecs / 1000 > (s64)0x7fffffffffffffffULL / (s64)HZ) | |
739 | timeout_jiffies = -1; | |
740 | else | |
741 | #endif | |
742 | timeout_jiffies = msecs_to_jiffies(timeout_msecs) + 1; | |
743 | } else { | |
744 | /* Infinite (< 0) or no (0) timeout */ | |
745 | timeout_jiffies = timeout_msecs; | |
746 | } | |
747 | ||
748 | ret = do_sys_poll(ufds, nfds, &timeout_jiffies); | |
749 | if (ret == -EINTR) { | |
750 | struct restart_block *restart_block; | |
751 | restart_block = ¤t_thread_info()->restart_block; | |
752 | restart_block->fn = do_restart_poll; | |
753 | restart_block->arg0 = (unsigned long)ufds; | |
754 | restart_block->arg1 = nfds; | |
755 | restart_block->arg2 = timeout_jiffies & 0xFFFFFFFF; | |
756 | restart_block->arg3 = (u64)timeout_jiffies >> 32; | |
757 | ret = -ERESTART_RESTARTBLOCK; | |
758 | } | |
759 | return ret; | |
760 | } | |
761 | ||
762 | #ifdef TIF_RESTORE_SIGMASK | |
763 | asmlinkage long sys_ppoll(struct pollfd __user *ufds, unsigned int nfds, | |
764 | struct timespec __user *tsp, const sigset_t __user *sigmask, | |
765 | size_t sigsetsize) | |
766 | { | |
767 | sigset_t ksigmask, sigsaved; | |
768 | struct timespec ts; | |
769 | s64 timeout = -1; | |
770 | int ret; | |
771 | ||
772 | if (tsp) { | |
773 | if (copy_from_user(&ts, tsp, sizeof(ts))) | |
774 | return -EFAULT; | |
775 | ||
776 | /* Cast to u64 to make GCC stop complaining */ | |
777 | if ((u64)ts.tv_sec >= (u64)MAX_INT64_SECONDS) | |
778 | timeout = -1; /* infinite */ | |
779 | else { | |
780 | timeout = DIV_ROUND_UP(ts.tv_nsec, NSEC_PER_SEC/HZ); | |
781 | timeout += ts.tv_sec * HZ; | |
782 | } | |
783 | } | |
784 | ||
785 | if (sigmask) { | |
786 | /* XXX: Don't preclude handling different sized sigset_t's. */ | |
787 | if (sigsetsize != sizeof(sigset_t)) | |
788 | return -EINVAL; | |
789 | if (copy_from_user(&ksigmask, sigmask, sizeof(ksigmask))) | |
790 | return -EFAULT; | |
791 | ||
792 | sigdelsetmask(&ksigmask, sigmask(SIGKILL)|sigmask(SIGSTOP)); | |
793 | sigprocmask(SIG_SETMASK, &ksigmask, &sigsaved); | |
794 | } | |
795 | ||
796 | ret = do_sys_poll(ufds, nfds, &timeout); | |
797 | ||
798 | /* We can restart this syscall, usually */ | |
799 | if (ret == -EINTR) { | |
800 | /* | |
801 | * Don't restore the signal mask yet. Let do_signal() deliver | |
802 | * the signal on the way back to userspace, before the signal | |
803 | * mask is restored. | |
804 | */ | |
805 | if (sigmask) { | |
806 | memcpy(¤t->saved_sigmask, &sigsaved, | |
807 | sizeof(sigsaved)); | |
808 | set_thread_flag(TIF_RESTORE_SIGMASK); | |
809 | } | |
810 | ret = -ERESTARTNOHAND; | |
811 | } else if (sigmask) | |
812 | sigprocmask(SIG_SETMASK, &sigsaved, NULL); | |
813 | ||
814 | if (tsp && timeout >= 0) { | |
815 | struct timespec rts; | |
816 | ||
817 | if (current->personality & STICKY_TIMEOUTS) | |
818 | goto sticky; | |
819 | /* Yes, we know it's actually an s64, but it's also positive. */ | |
820 | rts.tv_nsec = jiffies_to_usecs(do_div((*(u64*)&timeout), HZ)) * | |
821 | 1000; | |
822 | rts.tv_sec = timeout; | |
823 | if (timespec_compare(&rts, &ts) >= 0) | |
824 | rts = ts; | |
825 | if (copy_to_user(tsp, &rts, sizeof(rts))) { | |
826 | sticky: | |
827 | /* | |
828 | * If an application puts its timeval in read-only | |
829 | * memory, we don't want the Linux-specific update to | |
830 | * the timeval to cause a fault after the select has | |
831 | * completed successfully. However, because we're not | |
832 | * updating the timeval, we can't restart the system | |
833 | * call. | |
834 | */ | |
835 | if (ret == -ERESTARTNOHAND && timeout >= 0) | |
836 | ret = -EINTR; | |
837 | } | |
838 | } | |
839 | ||
840 | return ret; | |
841 | } | |
842 | #endif /* TIF_RESTORE_SIGMASK */ |