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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/fdtable.h> | |
25 | #include <linux/fs.h> | |
26 | #include <linux/rcupdate.h> | |
27 | ||
28 | #include <asm/uaccess.h> | |
29 | ||
30 | struct poll_table_page { | |
31 | struct poll_table_page * next; | |
32 | struct poll_table_entry * entry; | |
33 | struct poll_table_entry entries[0]; | |
34 | }; | |
35 | ||
36 | #define POLL_TABLE_FULL(table) \ | |
37 | ((unsigned long)((table)->entry+1) > PAGE_SIZE + (unsigned long)(table)) | |
38 | ||
39 | /* | |
40 | * Ok, Peter made a complicated, but straightforward multiple_wait() function. | |
41 | * I have rewritten this, taking some shortcuts: This code may not be easy to | |
42 | * follow, but it should be free of race-conditions, and it's practical. If you | |
43 | * understand what I'm doing here, then you understand how the linux | |
44 | * sleep/wakeup mechanism works. | |
45 | * | |
46 | * Two very simple procedures, poll_wait() and poll_freewait() make all the | |
47 | * work. poll_wait() is an inline-function defined in <linux/poll.h>, | |
48 | * as all select/poll functions have to call it to add an entry to the | |
49 | * poll table. | |
50 | */ | |
51 | static void __pollwait(struct file *filp, wait_queue_head_t *wait_address, | |
52 | poll_table *p); | |
53 | ||
54 | void poll_initwait(struct poll_wqueues *pwq) | |
55 | { | |
56 | init_poll_funcptr(&pwq->pt, __pollwait); | |
57 | pwq->error = 0; | |
58 | pwq->table = NULL; | |
59 | pwq->inline_index = 0; | |
60 | } | |
61 | ||
62 | EXPORT_SYMBOL(poll_initwait); | |
63 | ||
64 | static void free_poll_entry(struct poll_table_entry *entry) | |
65 | { | |
66 | remove_wait_queue(entry->wait_address, &entry->wait); | |
67 | fput(entry->filp); | |
68 | } | |
69 | ||
70 | void poll_freewait(struct poll_wqueues *pwq) | |
71 | { | |
72 | struct poll_table_page * p = pwq->table; | |
73 | int i; | |
74 | for (i = 0; i < pwq->inline_index; i++) | |
75 | free_poll_entry(pwq->inline_entries + i); | |
76 | while (p) { | |
77 | struct poll_table_entry * entry; | |
78 | struct poll_table_page *old; | |
79 | ||
80 | entry = p->entry; | |
81 | do { | |
82 | entry--; | |
83 | free_poll_entry(entry); | |
84 | } while (entry > p->entries); | |
85 | old = p; | |
86 | p = p->next; | |
87 | free_page((unsigned long) old); | |
88 | } | |
89 | } | |
90 | ||
91 | EXPORT_SYMBOL(poll_freewait); | |
92 | ||
93 | static struct poll_table_entry *poll_get_entry(poll_table *_p) | |
94 | { | |
95 | struct poll_wqueues *p = container_of(_p, struct poll_wqueues, pt); | |
96 | struct poll_table_page *table = p->table; | |
97 | ||
98 | if (p->inline_index < N_INLINE_POLL_ENTRIES) | |
99 | return p->inline_entries + p->inline_index++; | |
100 | ||
101 | if (!table || POLL_TABLE_FULL(table)) { | |
102 | struct poll_table_page *new_table; | |
103 | ||
104 | new_table = (struct poll_table_page *) __get_free_page(GFP_KERNEL); | |
105 | if (!new_table) { | |
106 | p->error = -ENOMEM; | |
107 | __set_current_state(TASK_RUNNING); | |
108 | return NULL; | |
109 | } | |
110 | new_table->entry = new_table->entries; | |
111 | new_table->next = table; | |
112 | p->table = new_table; | |
113 | table = new_table; | |
114 | } | |
115 | ||
116 | return table->entry++; | |
117 | } | |
118 | ||
119 | /* Add a new entry */ | |
120 | static void __pollwait(struct file *filp, wait_queue_head_t *wait_address, | |
121 | poll_table *p) | |
122 | { | |
123 | struct poll_table_entry *entry = poll_get_entry(p); | |
124 | if (!entry) | |
125 | return; | |
126 | get_file(filp); | |
127 | entry->filp = filp; | |
128 | entry->wait_address = wait_address; | |
129 | init_waitqueue_entry(&entry->wait, current); | |
130 | add_wait_queue(wait_address, &entry->wait); | |
131 | } | |
132 | ||
133 | #define FDS_IN(fds, n) (fds->in + n) | |
134 | #define FDS_OUT(fds, n) (fds->out + n) | |
135 | #define FDS_EX(fds, n) (fds->ex + n) | |
136 | ||
137 | #define BITS(fds, n) (*FDS_IN(fds, n)|*FDS_OUT(fds, n)|*FDS_EX(fds, n)) | |
138 | ||
139 | static int max_select_fd(unsigned long n, fd_set_bits *fds) | |
140 | { | |
141 | unsigned long *open_fds; | |
142 | unsigned long set; | |
143 | int max; | |
144 | struct fdtable *fdt; | |
145 | ||
146 | /* handle last in-complete long-word first */ | |
147 | set = ~(~0UL << (n & (__NFDBITS-1))); | |
148 | n /= __NFDBITS; | |
149 | fdt = files_fdtable(current->files); | |
150 | open_fds = fdt->open_fds->fds_bits+n; | |
151 | max = 0; | |
152 | if (set) { | |
153 | set &= BITS(fds, n); | |
154 | if (set) { | |
155 | if (!(set & ~*open_fds)) | |
156 | goto get_max; | |
157 | return -EBADF; | |
158 | } | |
159 | } | |
160 | while (n) { | |
161 | open_fds--; | |
162 | n--; | |
163 | set = BITS(fds, n); | |
164 | if (!set) | |
165 | continue; | |
166 | if (set & ~*open_fds) | |
167 | return -EBADF; | |
168 | if (max) | |
169 | continue; | |
170 | get_max: | |
171 | do { | |
172 | max++; | |
173 | set >>= 1; | |
174 | } while (set); | |
175 | max += n * __NFDBITS; | |
176 | } | |
177 | ||
178 | return max; | |
179 | } | |
180 | ||
181 | #define POLLIN_SET (POLLRDNORM | POLLRDBAND | POLLIN | POLLHUP | POLLERR) | |
182 | #define POLLOUT_SET (POLLWRBAND | POLLWRNORM | POLLOUT | POLLERR) | |
183 | #define POLLEX_SET (POLLPRI) | |
184 | ||
185 | int do_select(int n, fd_set_bits *fds, s64 *timeout) | |
186 | { | |
187 | struct poll_wqueues table; | |
188 | poll_table *wait; | |
189 | int retval, i; | |
190 | ||
191 | rcu_read_lock(); | |
192 | retval = max_select_fd(n, fds); | |
193 | rcu_read_unlock(); | |
194 | ||
195 | if (retval < 0) | |
196 | return retval; | |
197 | n = retval; | |
198 | ||
199 | poll_initwait(&table); | |
200 | wait = &table.pt; | |
201 | if (!*timeout) | |
202 | wait = NULL; | |
203 | retval = 0; | |
204 | for (;;) { | |
205 | unsigned long *rinp, *routp, *rexp, *inp, *outp, *exp; | |
206 | long __timeout; | |
207 | ||
208 | set_current_state(TASK_INTERRUPTIBLE); | |
209 | ||
210 | inp = fds->in; outp = fds->out; exp = fds->ex; | |
211 | rinp = fds->res_in; routp = fds->res_out; rexp = fds->res_ex; | |
212 | ||
213 | for (i = 0; i < n; ++rinp, ++routp, ++rexp) { | |
214 | unsigned long in, out, ex, all_bits, bit = 1, mask, j; | |
215 | unsigned long res_in = 0, res_out = 0, res_ex = 0; | |
216 | const struct file_operations *f_op = NULL; | |
217 | struct file *file = NULL; | |
218 | ||
219 | in = *inp++; out = *outp++; ex = *exp++; | |
220 | all_bits = in | out | ex; | |
221 | if (all_bits == 0) { | |
222 | i += __NFDBITS; | |
223 | continue; | |
224 | } | |
225 | ||
226 | for (j = 0; j < __NFDBITS; ++j, ++i, bit <<= 1) { | |
227 | int fput_needed; | |
228 | if (i >= n) | |
229 | break; | |
230 | if (!(bit & all_bits)) | |
231 | continue; | |
232 | file = fget_light(i, &fput_needed); | |
233 | if (file) { | |
234 | f_op = file->f_op; | |
235 | mask = DEFAULT_POLLMASK; | |
236 | if (f_op && f_op->poll) | |
237 | mask = (*f_op->poll)(file, retval ? NULL : wait); | |
238 | fput_light(file, fput_needed); | |
239 | if ((mask & POLLIN_SET) && (in & bit)) { | |
240 | res_in |= bit; | |
241 | retval++; | |
242 | } | |
243 | if ((mask & POLLOUT_SET) && (out & bit)) { | |
244 | res_out |= bit; | |
245 | retval++; | |
246 | } | |
247 | if ((mask & POLLEX_SET) && (ex & bit)) { | |
248 | res_ex |= bit; | |
249 | retval++; | |
250 | } | |
251 | } | |
252 | cond_resched(); | |
253 | } | |
254 | if (res_in) | |
255 | *rinp = res_in; | |
256 | if (res_out) | |
257 | *routp = res_out; | |
258 | if (res_ex) | |
259 | *rexp = res_ex; | |
260 | } | |
261 | wait = NULL; | |
262 | if (retval || !*timeout || signal_pending(current)) | |
263 | break; | |
264 | if (table.error) { | |
265 | retval = table.error; | |
266 | break; | |
267 | } | |
268 | ||
269 | if (*timeout < 0) { | |
270 | /* Wait indefinitely */ | |
271 | __timeout = MAX_SCHEDULE_TIMEOUT; | |
272 | } else if (unlikely(*timeout >= (s64)MAX_SCHEDULE_TIMEOUT - 1)) { | |
273 | /* Wait for longer than MAX_SCHEDULE_TIMEOUT. Do it in a loop */ | |
274 | __timeout = MAX_SCHEDULE_TIMEOUT - 1; | |
275 | *timeout -= __timeout; | |
276 | } else { | |
277 | __timeout = *timeout; | |
278 | *timeout = 0; | |
279 | } | |
280 | __timeout = schedule_timeout(__timeout); | |
281 | if (*timeout >= 0) | |
282 | *timeout += __timeout; | |
283 | } | |
284 | __set_current_state(TASK_RUNNING); | |
285 | ||
286 | poll_freewait(&table); | |
287 | ||
288 | return retval; | |
289 | } | |
290 | ||
291 | /* | |
292 | * We can actually return ERESTARTSYS instead of EINTR, but I'd | |
293 | * like to be certain this leads to no problems. So I return | |
294 | * EINTR just for safety. | |
295 | * | |
296 | * Update: ERESTARTSYS breaks at least the xview clock binary, so | |
297 | * I'm trying ERESTARTNOHAND which restart only when you want to. | |
298 | */ | |
299 | #define MAX_SELECT_SECONDS \ | |
300 | ((unsigned long) (MAX_SCHEDULE_TIMEOUT / HZ)-1) | |
301 | ||
302 | int core_sys_select(int n, fd_set __user *inp, fd_set __user *outp, | |
303 | fd_set __user *exp, s64 *timeout) | |
304 | { | |
305 | fd_set_bits fds; | |
306 | void *bits; | |
307 | int ret, max_fds; | |
308 | unsigned int size; | |
309 | struct fdtable *fdt; | |
310 | /* Allocate small arguments on the stack to save memory and be faster */ | |
311 | long stack_fds[SELECT_STACK_ALLOC/sizeof(long)]; | |
312 | ||
313 | ret = -EINVAL; | |
314 | if (n < 0) | |
315 | goto out_nofds; | |
316 | ||
317 | /* max_fds can increase, so grab it once to avoid race */ | |
318 | rcu_read_lock(); | |
319 | fdt = files_fdtable(current->files); | |
320 | max_fds = fdt->max_fds; | |
321 | rcu_read_unlock(); | |
322 | if (n > max_fds) | |
323 | n = max_fds; | |
324 | ||
325 | /* | |
326 | * We need 6 bitmaps (in/out/ex for both incoming and outgoing), | |
327 | * since we used fdset we need to allocate memory in units of | |
328 | * long-words. | |
329 | */ | |
330 | size = FDS_BYTES(n); | |
331 | bits = stack_fds; | |
332 | if (size > sizeof(stack_fds) / 6) { | |
333 | /* Not enough space in on-stack array; must use kmalloc */ | |
334 | ret = -ENOMEM; | |
335 | bits = kmalloc(6 * size, GFP_KERNEL); | |
336 | if (!bits) | |
337 | goto out_nofds; | |
338 | } | |
339 | fds.in = bits; | |
340 | fds.out = bits + size; | |
341 | fds.ex = bits + 2*size; | |
342 | fds.res_in = bits + 3*size; | |
343 | fds.res_out = bits + 4*size; | |
344 | fds.res_ex = bits + 5*size; | |
345 | ||
346 | if ((ret = get_fd_set(n, inp, fds.in)) || | |
347 | (ret = get_fd_set(n, outp, fds.out)) || | |
348 | (ret = get_fd_set(n, exp, fds.ex))) | |
349 | goto out; | |
350 | zero_fd_set(n, fds.res_in); | |
351 | zero_fd_set(n, fds.res_out); | |
352 | zero_fd_set(n, fds.res_ex); | |
353 | ||
354 | ret = do_select(n, &fds, timeout); | |
355 | ||
356 | if (ret < 0) | |
357 | goto out; | |
358 | if (!ret) { | |
359 | ret = -ERESTARTNOHAND; | |
360 | if (signal_pending(current)) | |
361 | goto out; | |
362 | ret = 0; | |
363 | } | |
364 | ||
365 | if (set_fd_set(n, inp, fds.res_in) || | |
366 | set_fd_set(n, outp, fds.res_out) || | |
367 | set_fd_set(n, exp, fds.res_ex)) | |
368 | ret = -EFAULT; | |
369 | ||
370 | out: | |
371 | if (bits != stack_fds) | |
372 | kfree(bits); | |
373 | out_nofds: | |
374 | return ret; | |
375 | } | |
376 | ||
377 | asmlinkage long sys_select(int n, fd_set __user *inp, fd_set __user *outp, | |
378 | fd_set __user *exp, struct timeval __user *tvp) | |
379 | { | |
380 | s64 timeout = -1; | |
381 | struct timeval tv; | |
382 | int ret; | |
383 | ||
384 | if (tvp) { | |
385 | if (copy_from_user(&tv, tvp, sizeof(tv))) | |
386 | return -EFAULT; | |
387 | ||
388 | if (tv.tv_sec < 0 || tv.tv_usec < 0) | |
389 | return -EINVAL; | |
390 | ||
391 | /* Cast to u64 to make GCC stop complaining */ | |
392 | if ((u64)tv.tv_sec >= (u64)MAX_INT64_SECONDS) | |
393 | timeout = -1; /* infinite */ | |
394 | else { | |
395 | timeout = DIV_ROUND_UP(tv.tv_usec, USEC_PER_SEC/HZ); | |
396 | timeout += tv.tv_sec * HZ; | |
397 | } | |
398 | } | |
399 | ||
400 | ret = core_sys_select(n, inp, outp, exp, &timeout); | |
401 | ||
402 | if (tvp) { | |
403 | struct timeval rtv; | |
404 | ||
405 | if (current->personality & STICKY_TIMEOUTS) | |
406 | goto sticky; | |
407 | rtv.tv_usec = jiffies_to_usecs(do_div((*(u64*)&timeout), HZ)); | |
408 | rtv.tv_sec = timeout; | |
409 | if (timeval_compare(&rtv, &tv) >= 0) | |
410 | rtv = tv; | |
411 | if (copy_to_user(tvp, &rtv, sizeof(rtv))) { | |
412 | sticky: | |
413 | /* | |
414 | * If an application puts its timeval in read-only | |
415 | * memory, we don't want the Linux-specific update to | |
416 | * the timeval to cause a fault after the select has | |
417 | * completed successfully. However, because we're not | |
418 | * updating the timeval, we can't restart the system | |
419 | * call. | |
420 | */ | |
421 | if (ret == -ERESTARTNOHAND) | |
422 | ret = -EINTR; | |
423 | } | |
424 | } | |
425 | ||
426 | return ret; | |
427 | } | |
428 | ||
429 | #ifdef HAVE_SET_RESTORE_SIGMASK | |
430 | asmlinkage long sys_pselect7(int n, fd_set __user *inp, fd_set __user *outp, | |
431 | fd_set __user *exp, struct timespec __user *tsp, | |
432 | const sigset_t __user *sigmask, size_t sigsetsize) | |
433 | { | |
434 | s64 timeout = MAX_SCHEDULE_TIMEOUT; | |
435 | sigset_t ksigmask, sigsaved; | |
436 | struct timespec ts; | |
437 | int ret; | |
438 | ||
439 | if (tsp) { | |
440 | if (copy_from_user(&ts, tsp, sizeof(ts))) | |
441 | return -EFAULT; | |
442 | ||
443 | if (ts.tv_sec < 0 || ts.tv_nsec < 0) | |
444 | return -EINVAL; | |
445 | ||
446 | /* Cast to u64 to make GCC stop complaining */ | |
447 | if ((u64)ts.tv_sec >= (u64)MAX_INT64_SECONDS) | |
448 | timeout = -1; /* infinite */ | |
449 | else { | |
450 | timeout = DIV_ROUND_UP(ts.tv_nsec, NSEC_PER_SEC/HZ); | |
451 | timeout += ts.tv_sec * HZ; | |
452 | } | |
453 | } | |
454 | ||
455 | if (sigmask) { | |
456 | /* XXX: Don't preclude handling different sized sigset_t's. */ | |
457 | if (sigsetsize != sizeof(sigset_t)) | |
458 | return -EINVAL; | |
459 | if (copy_from_user(&ksigmask, sigmask, sizeof(ksigmask))) | |
460 | return -EFAULT; | |
461 | ||
462 | sigdelsetmask(&ksigmask, sigmask(SIGKILL)|sigmask(SIGSTOP)); | |
463 | sigprocmask(SIG_SETMASK, &ksigmask, &sigsaved); | |
464 | } | |
465 | ||
466 | ret = core_sys_select(n, inp, outp, exp, &timeout); | |
467 | ||
468 | if (tsp) { | |
469 | struct timespec rts; | |
470 | ||
471 | if (current->personality & STICKY_TIMEOUTS) | |
472 | goto sticky; | |
473 | rts.tv_nsec = jiffies_to_usecs(do_div((*(u64*)&timeout), HZ)) * | |
474 | 1000; | |
475 | rts.tv_sec = timeout; | |
476 | if (timespec_compare(&rts, &ts) >= 0) | |
477 | rts = ts; | |
478 | if (copy_to_user(tsp, &rts, sizeof(rts))) { | |
479 | sticky: | |
480 | /* | |
481 | * If an application puts its timeval in read-only | |
482 | * memory, we don't want the Linux-specific update to | |
483 | * the timeval to cause a fault after the select has | |
484 | * completed successfully. However, because we're not | |
485 | * updating the timeval, we can't restart the system | |
486 | * call. | |
487 | */ | |
488 | if (ret == -ERESTARTNOHAND) | |
489 | ret = -EINTR; | |
490 | } | |
491 | } | |
492 | ||
493 | if (ret == -ERESTARTNOHAND) { | |
494 | /* | |
495 | * Don't restore the signal mask yet. Let do_signal() deliver | |
496 | * the signal on the way back to userspace, before the signal | |
497 | * mask is restored. | |
498 | */ | |
499 | if (sigmask) { | |
500 | memcpy(¤t->saved_sigmask, &sigsaved, | |
501 | sizeof(sigsaved)); | |
502 | set_restore_sigmask(); | |
503 | } | |
504 | } else if (sigmask) | |
505 | sigprocmask(SIG_SETMASK, &sigsaved, NULL); | |
506 | ||
507 | return ret; | |
508 | } | |
509 | ||
510 | /* | |
511 | * Most architectures can't handle 7-argument syscalls. So we provide a | |
512 | * 6-argument version where the sixth argument is a pointer to a structure | |
513 | * which has a pointer to the sigset_t itself followed by a size_t containing | |
514 | * the sigset size. | |
515 | */ | |
516 | asmlinkage long sys_pselect6(int n, fd_set __user *inp, fd_set __user *outp, | |
517 | fd_set __user *exp, struct timespec __user *tsp, void __user *sig) | |
518 | { | |
519 | size_t sigsetsize = 0; | |
520 | sigset_t __user *up = NULL; | |
521 | ||
522 | if (sig) { | |
523 | if (!access_ok(VERIFY_READ, sig, sizeof(void *)+sizeof(size_t)) | |
524 | || __get_user(up, (sigset_t __user * __user *)sig) | |
525 | || __get_user(sigsetsize, | |
526 | (size_t __user *)(sig+sizeof(void *)))) | |
527 | return -EFAULT; | |
528 | } | |
529 | ||
530 | return sys_pselect7(n, inp, outp, exp, tsp, up, sigsetsize); | |
531 | } | |
532 | #endif /* HAVE_SET_RESTORE_SIGMASK */ | |
533 | ||
534 | struct poll_list { | |
535 | struct poll_list *next; | |
536 | int len; | |
537 | struct pollfd entries[0]; | |
538 | }; | |
539 | ||
540 | #define POLLFD_PER_PAGE ((PAGE_SIZE-sizeof(struct poll_list)) / sizeof(struct pollfd)) | |
541 | ||
542 | /* | |
543 | * Fish for pollable events on the pollfd->fd file descriptor. We're only | |
544 | * interested in events matching the pollfd->events mask, and the result | |
545 | * matching that mask is both recorded in pollfd->revents and returned. The | |
546 | * pwait poll_table will be used by the fd-provided poll handler for waiting, | |
547 | * if non-NULL. | |
548 | */ | |
549 | static inline unsigned int do_pollfd(struct pollfd *pollfd, poll_table *pwait) | |
550 | { | |
551 | unsigned int mask; | |
552 | int fd; | |
553 | ||
554 | mask = 0; | |
555 | fd = pollfd->fd; | |
556 | if (fd >= 0) { | |
557 | int fput_needed; | |
558 | struct file * file; | |
559 | ||
560 | file = fget_light(fd, &fput_needed); | |
561 | mask = POLLNVAL; | |
562 | if (file != NULL) { | |
563 | mask = DEFAULT_POLLMASK; | |
564 | if (file->f_op && file->f_op->poll) | |
565 | mask = file->f_op->poll(file, pwait); | |
566 | /* Mask out unneeded events. */ | |
567 | mask &= pollfd->events | POLLERR | POLLHUP; | |
568 | fput_light(file, fput_needed); | |
569 | } | |
570 | } | |
571 | pollfd->revents = mask; | |
572 | ||
573 | return mask; | |
574 | } | |
575 | ||
576 | static int do_poll(unsigned int nfds, struct poll_list *list, | |
577 | struct poll_wqueues *wait, s64 *timeout) | |
578 | { | |
579 | int count = 0; | |
580 | poll_table* pt = &wait->pt; | |
581 | ||
582 | /* Optimise the no-wait case */ | |
583 | if (!(*timeout)) | |
584 | pt = NULL; | |
585 | ||
586 | for (;;) { | |
587 | struct poll_list *walk; | |
588 | long __timeout; | |
589 | ||
590 | set_current_state(TASK_INTERRUPTIBLE); | |
591 | for (walk = list; walk != NULL; walk = walk->next) { | |
592 | struct pollfd * pfd, * pfd_end; | |
593 | ||
594 | pfd = walk->entries; | |
595 | pfd_end = pfd + walk->len; | |
596 | for (; pfd != pfd_end; pfd++) { | |
597 | /* | |
598 | * Fish for events. If we found one, record it | |
599 | * and kill the poll_table, so we don't | |
600 | * needlessly register any other waiters after | |
601 | * this. They'll get immediately deregistered | |
602 | * when we break out and return. | |
603 | */ | |
604 | if (do_pollfd(pfd, pt)) { | |
605 | count++; | |
606 | pt = NULL; | |
607 | } | |
608 | } | |
609 | } | |
610 | /* | |
611 | * All waiters have already been registered, so don't provide | |
612 | * a poll_table to them on the next loop iteration. | |
613 | */ | |
614 | pt = NULL; | |
615 | if (!count) { | |
616 | count = wait->error; | |
617 | if (signal_pending(current)) | |
618 | count = -EINTR; | |
619 | } | |
620 | if (count || !*timeout) | |
621 | break; | |
622 | ||
623 | if (*timeout < 0) { | |
624 | /* Wait indefinitely */ | |
625 | __timeout = MAX_SCHEDULE_TIMEOUT; | |
626 | } else if (unlikely(*timeout >= (s64)MAX_SCHEDULE_TIMEOUT-1)) { | |
627 | /* | |
628 | * Wait for longer than MAX_SCHEDULE_TIMEOUT. Do it in | |
629 | * a loop | |
630 | */ | |
631 | __timeout = MAX_SCHEDULE_TIMEOUT - 1; | |
632 | *timeout -= __timeout; | |
633 | } else { | |
634 | __timeout = *timeout; | |
635 | *timeout = 0; | |
636 | } | |
637 | ||
638 | __timeout = schedule_timeout(__timeout); | |
639 | if (*timeout >= 0) | |
640 | *timeout += __timeout; | |
641 | } | |
642 | __set_current_state(TASK_RUNNING); | |
643 | return count; | |
644 | } | |
645 | ||
646 | #define N_STACK_PPS ((sizeof(stack_pps) - sizeof(struct poll_list)) / \ | |
647 | sizeof(struct pollfd)) | |
648 | ||
649 | int do_sys_poll(struct pollfd __user *ufds, unsigned int nfds, s64 *timeout) | |
650 | { | |
651 | struct poll_wqueues table; | |
652 | int err = -EFAULT, fdcount, len, size; | |
653 | /* Allocate small arguments on the stack to save memory and be | |
654 | faster - use long to make sure the buffer is aligned properly | |
655 | on 64 bit archs to avoid unaligned access */ | |
656 | long stack_pps[POLL_STACK_ALLOC/sizeof(long)]; | |
657 | struct poll_list *const head = (struct poll_list *)stack_pps; | |
658 | struct poll_list *walk = head; | |
659 | unsigned long todo = nfds; | |
660 | ||
661 | if (nfds > current->signal->rlim[RLIMIT_NOFILE].rlim_cur) | |
662 | return -EINVAL; | |
663 | ||
664 | len = min_t(unsigned int, nfds, N_STACK_PPS); | |
665 | for (;;) { | |
666 | walk->next = NULL; | |
667 | walk->len = len; | |
668 | if (!len) | |
669 | break; | |
670 | ||
671 | if (copy_from_user(walk->entries, ufds + nfds-todo, | |
672 | sizeof(struct pollfd) * walk->len)) | |
673 | goto out_fds; | |
674 | ||
675 | todo -= walk->len; | |
676 | if (!todo) | |
677 | break; | |
678 | ||
679 | len = min(todo, POLLFD_PER_PAGE); | |
680 | size = sizeof(struct poll_list) + sizeof(struct pollfd) * len; | |
681 | walk = walk->next = kmalloc(size, GFP_KERNEL); | |
682 | if (!walk) { | |
683 | err = -ENOMEM; | |
684 | goto out_fds; | |
685 | } | |
686 | } | |
687 | ||
688 | poll_initwait(&table); | |
689 | fdcount = do_poll(nfds, head, &table, timeout); | |
690 | poll_freewait(&table); | |
691 | ||
692 | for (walk = head; walk; walk = walk->next) { | |
693 | struct pollfd *fds = walk->entries; | |
694 | int j; | |
695 | ||
696 | for (j = 0; j < walk->len; j++, ufds++) | |
697 | if (__put_user(fds[j].revents, &ufds->revents)) | |
698 | goto out_fds; | |
699 | } | |
700 | ||
701 | err = fdcount; | |
702 | out_fds: | |
703 | walk = head->next; | |
704 | while (walk) { | |
705 | struct poll_list *pos = walk; | |
706 | walk = walk->next; | |
707 | kfree(pos); | |
708 | } | |
709 | ||
710 | return err; | |
711 | } | |
712 | ||
713 | static long do_restart_poll(struct restart_block *restart_block) | |
714 | { | |
715 | struct pollfd __user *ufds = (struct pollfd __user*)restart_block->arg0; | |
716 | int nfds = restart_block->arg1; | |
717 | s64 timeout = ((s64)restart_block->arg3<<32) | (s64)restart_block->arg2; | |
718 | int ret; | |
719 | ||
720 | ret = do_sys_poll(ufds, nfds, &timeout); | |
721 | if (ret == -EINTR) { | |
722 | restart_block->fn = do_restart_poll; | |
723 | restart_block->arg2 = timeout & 0xFFFFFFFF; | |
724 | restart_block->arg3 = (u64)timeout >> 32; | |
725 | ret = -ERESTART_RESTARTBLOCK; | |
726 | } | |
727 | return ret; | |
728 | } | |
729 | ||
730 | asmlinkage long sys_poll(struct pollfd __user *ufds, unsigned int nfds, | |
731 | long timeout_msecs) | |
732 | { | |
733 | s64 timeout_jiffies; | |
734 | int ret; | |
735 | ||
736 | if (timeout_msecs > 0) { | |
737 | #if HZ > 1000 | |
738 | /* We can only overflow if HZ > 1000 */ | |
739 | if (timeout_msecs / 1000 > (s64)0x7fffffffffffffffULL / (s64)HZ) | |
740 | timeout_jiffies = -1; | |
741 | else | |
742 | #endif | |
743 | timeout_jiffies = msecs_to_jiffies(timeout_msecs) + 1; | |
744 | } else { | |
745 | /* Infinite (< 0) or no (0) timeout */ | |
746 | timeout_jiffies = timeout_msecs; | |
747 | } | |
748 | ||
749 | ret = do_sys_poll(ufds, nfds, &timeout_jiffies); | |
750 | if (ret == -EINTR) { | |
751 | struct restart_block *restart_block; | |
752 | restart_block = ¤t_thread_info()->restart_block; | |
753 | restart_block->fn = do_restart_poll; | |
754 | restart_block->arg0 = (unsigned long)ufds; | |
755 | restart_block->arg1 = nfds; | |
756 | restart_block->arg2 = timeout_jiffies & 0xFFFFFFFF; | |
757 | restart_block->arg3 = (u64)timeout_jiffies >> 32; | |
758 | ret = -ERESTART_RESTARTBLOCK; | |
759 | } | |
760 | return ret; | |
761 | } | |
762 | ||
763 | #ifdef HAVE_SET_RESTORE_SIGMASK | |
764 | asmlinkage long sys_ppoll(struct pollfd __user *ufds, unsigned int nfds, | |
765 | struct timespec __user *tsp, const sigset_t __user *sigmask, | |
766 | size_t sigsetsize) | |
767 | { | |
768 | sigset_t ksigmask, sigsaved; | |
769 | struct timespec ts; | |
770 | s64 timeout = -1; | |
771 | int ret; | |
772 | ||
773 | if (tsp) { | |
774 | if (copy_from_user(&ts, tsp, sizeof(ts))) | |
775 | return -EFAULT; | |
776 | ||
777 | /* Cast to u64 to make GCC stop complaining */ | |
778 | if ((u64)ts.tv_sec >= (u64)MAX_INT64_SECONDS) | |
779 | timeout = -1; /* infinite */ | |
780 | else { | |
781 | timeout = DIV_ROUND_UP(ts.tv_nsec, NSEC_PER_SEC/HZ); | |
782 | timeout += ts.tv_sec * HZ; | |
783 | } | |
784 | } | |
785 | ||
786 | if (sigmask) { | |
787 | /* XXX: Don't preclude handling different sized sigset_t's. */ | |
788 | if (sigsetsize != sizeof(sigset_t)) | |
789 | return -EINVAL; | |
790 | if (copy_from_user(&ksigmask, sigmask, sizeof(ksigmask))) | |
791 | return -EFAULT; | |
792 | ||
793 | sigdelsetmask(&ksigmask, sigmask(SIGKILL)|sigmask(SIGSTOP)); | |
794 | sigprocmask(SIG_SETMASK, &ksigmask, &sigsaved); | |
795 | } | |
796 | ||
797 | ret = do_sys_poll(ufds, nfds, &timeout); | |
798 | ||
799 | /* We can restart this syscall, usually */ | |
800 | if (ret == -EINTR) { | |
801 | /* | |
802 | * Don't restore the signal mask yet. Let do_signal() deliver | |
803 | * the signal on the way back to userspace, before the signal | |
804 | * mask is restored. | |
805 | */ | |
806 | if (sigmask) { | |
807 | memcpy(¤t->saved_sigmask, &sigsaved, | |
808 | sizeof(sigsaved)); | |
809 | set_restore_sigmask(); | |
810 | } | |
811 | ret = -ERESTARTNOHAND; | |
812 | } else if (sigmask) | |
813 | sigprocmask(SIG_SETMASK, &sigsaved, NULL); | |
814 | ||
815 | if (tsp && timeout >= 0) { | |
816 | struct timespec rts; | |
817 | ||
818 | if (current->personality & STICKY_TIMEOUTS) | |
819 | goto sticky; | |
820 | /* Yes, we know it's actually an s64, but it's also positive. */ | |
821 | rts.tv_nsec = jiffies_to_usecs(do_div((*(u64*)&timeout), HZ)) * | |
822 | 1000; | |
823 | rts.tv_sec = timeout; | |
824 | if (timespec_compare(&rts, &ts) >= 0) | |
825 | rts = ts; | |
826 | if (copy_to_user(tsp, &rts, sizeof(rts))) { | |
827 | sticky: | |
828 | /* | |
829 | * If an application puts its timeval in read-only | |
830 | * memory, we don't want the Linux-specific update to | |
831 | * the timeval to cause a fault after the select has | |
832 | * completed successfully. However, because we're not | |
833 | * updating the timeval, we can't restart the system | |
834 | * call. | |
835 | */ | |
836 | if (ret == -ERESTARTNOHAND && timeout >= 0) | |
837 | ret = -EINTR; | |
838 | } | |
839 | } | |
840 | ||
841 | return ret; | |
842 | } | |
843 | #endif /* HAVE_SET_RESTORE_SIGMASK */ |