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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/sched.h> | |
19 | #include <linux/syscalls.h> | |
20 | #include <linux/export.h> | |
21 | #include <linux/slab.h> | |
22 | #include <linux/poll.h> | |
23 | #include <linux/personality.h> /* for STICKY_TIMEOUTS */ | |
24 | #include <linux/file.h> | |
25 | #include <linux/fdtable.h> | |
26 | #include <linux/fs.h> | |
27 | #include <linux/rcupdate.h> | |
28 | #include <linux/hrtimer.h> | |
29 | #include <linux/sched/rt.h> | |
30 | #include <linux/freezer.h> | |
31 | #include <net/busy_poll.h> | |
32 | ||
33 | #include <asm/uaccess.h> | |
34 | ||
35 | ||
36 | /* | |
37 | * Estimate expected accuracy in ns from a timeval. | |
38 | * | |
39 | * After quite a bit of churning around, we've settled on | |
40 | * a simple thing of taking 0.1% of the timeout as the | |
41 | * slack, with a cap of 100 msec. | |
42 | * "nice" tasks get a 0.5% slack instead. | |
43 | * | |
44 | * Consider this comment an open invitation to come up with even | |
45 | * better solutions.. | |
46 | */ | |
47 | ||
48 | #define MAX_SLACK (100 * NSEC_PER_MSEC) | |
49 | ||
50 | static long __estimate_accuracy(struct timespec *tv) | |
51 | { | |
52 | long slack; | |
53 | int divfactor = 1000; | |
54 | ||
55 | if (tv->tv_sec < 0) | |
56 | return 0; | |
57 | ||
58 | if (task_nice(current) > 0) | |
59 | divfactor = divfactor / 5; | |
60 | ||
61 | if (tv->tv_sec > MAX_SLACK / (NSEC_PER_SEC/divfactor)) | |
62 | return MAX_SLACK; | |
63 | ||
64 | slack = tv->tv_nsec / divfactor; | |
65 | slack += tv->tv_sec * (NSEC_PER_SEC/divfactor); | |
66 | ||
67 | if (slack > MAX_SLACK) | |
68 | return MAX_SLACK; | |
69 | ||
70 | return slack; | |
71 | } | |
72 | ||
73 | long select_estimate_accuracy(struct timespec *tv) | |
74 | { | |
75 | unsigned long ret; | |
76 | struct timespec now; | |
77 | ||
78 | /* | |
79 | * Realtime tasks get a slack of 0 for obvious reasons. | |
80 | */ | |
81 | ||
82 | if (rt_task(current)) | |
83 | return 0; | |
84 | ||
85 | ktime_get_ts(&now); | |
86 | now = timespec_sub(*tv, now); | |
87 | ret = __estimate_accuracy(&now); | |
88 | if (ret < current->timer_slack_ns) | |
89 | return current->timer_slack_ns; | |
90 | return ret; | |
91 | } | |
92 | ||
93 | ||
94 | ||
95 | struct poll_table_page { | |
96 | struct poll_table_page * next; | |
97 | struct poll_table_entry * entry; | |
98 | struct poll_table_entry entries[0]; | |
99 | }; | |
100 | ||
101 | #define POLL_TABLE_FULL(table) \ | |
102 | ((unsigned long)((table)->entry+1) > PAGE_SIZE + (unsigned long)(table)) | |
103 | ||
104 | /* | |
105 | * Ok, Peter made a complicated, but straightforward multiple_wait() function. | |
106 | * I have rewritten this, taking some shortcuts: This code may not be easy to | |
107 | * follow, but it should be free of race-conditions, and it's practical. If you | |
108 | * understand what I'm doing here, then you understand how the linux | |
109 | * sleep/wakeup mechanism works. | |
110 | * | |
111 | * Two very simple procedures, poll_wait() and poll_freewait() make all the | |
112 | * work. poll_wait() is an inline-function defined in <linux/poll.h>, | |
113 | * as all select/poll functions have to call it to add an entry to the | |
114 | * poll table. | |
115 | */ | |
116 | static void __pollwait(struct file *filp, wait_queue_head_t *wait_address, | |
117 | poll_table *p); | |
118 | ||
119 | void poll_initwait(struct poll_wqueues *pwq) | |
120 | { | |
121 | init_poll_funcptr(&pwq->pt, __pollwait); | |
122 | pwq->polling_task = current; | |
123 | pwq->triggered = 0; | |
124 | pwq->error = 0; | |
125 | pwq->table = NULL; | |
126 | pwq->inline_index = 0; | |
127 | } | |
128 | EXPORT_SYMBOL(poll_initwait); | |
129 | ||
130 | static void free_poll_entry(struct poll_table_entry *entry) | |
131 | { | |
132 | remove_wait_queue(entry->wait_address, &entry->wait); | |
133 | fput(entry->filp); | |
134 | } | |
135 | ||
136 | void poll_freewait(struct poll_wqueues *pwq) | |
137 | { | |
138 | struct poll_table_page * p = pwq->table; | |
139 | int i; | |
140 | for (i = 0; i < pwq->inline_index; i++) | |
141 | free_poll_entry(pwq->inline_entries + i); | |
142 | while (p) { | |
143 | struct poll_table_entry * entry; | |
144 | struct poll_table_page *old; | |
145 | ||
146 | entry = p->entry; | |
147 | do { | |
148 | entry--; | |
149 | free_poll_entry(entry); | |
150 | } while (entry > p->entries); | |
151 | old = p; | |
152 | p = p->next; | |
153 | free_page((unsigned long) old); | |
154 | } | |
155 | } | |
156 | EXPORT_SYMBOL(poll_freewait); | |
157 | ||
158 | static struct poll_table_entry *poll_get_entry(struct poll_wqueues *p) | |
159 | { | |
160 | struct poll_table_page *table = p->table; | |
161 | ||
162 | if (p->inline_index < N_INLINE_POLL_ENTRIES) | |
163 | return p->inline_entries + p->inline_index++; | |
164 | ||
165 | if (!table || POLL_TABLE_FULL(table)) { | |
166 | struct poll_table_page *new_table; | |
167 | ||
168 | new_table = (struct poll_table_page *) __get_free_page(GFP_KERNEL); | |
169 | if (!new_table) { | |
170 | p->error = -ENOMEM; | |
171 | return NULL; | |
172 | } | |
173 | new_table->entry = new_table->entries; | |
174 | new_table->next = table; | |
175 | p->table = new_table; | |
176 | table = new_table; | |
177 | } | |
178 | ||
179 | return table->entry++; | |
180 | } | |
181 | ||
182 | static int __pollwake(wait_queue_t *wait, unsigned mode, int sync, void *key) | |
183 | { | |
184 | struct poll_wqueues *pwq = wait->private; | |
185 | DECLARE_WAITQUEUE(dummy_wait, pwq->polling_task); | |
186 | ||
187 | /* | |
188 | * Although this function is called under waitqueue lock, LOCK | |
189 | * doesn't imply write barrier and the users expect write | |
190 | * barrier semantics on wakeup functions. The following | |
191 | * smp_wmb() is equivalent to smp_wmb() in try_to_wake_up() | |
192 | * and is paired with set_mb() in poll_schedule_timeout. | |
193 | */ | |
194 | smp_wmb(); | |
195 | pwq->triggered = 1; | |
196 | ||
197 | /* | |
198 | * Perform the default wake up operation using a dummy | |
199 | * waitqueue. | |
200 | * | |
201 | * TODO: This is hacky but there currently is no interface to | |
202 | * pass in @sync. @sync is scheduled to be removed and once | |
203 | * that happens, wake_up_process() can be used directly. | |
204 | */ | |
205 | return default_wake_function(&dummy_wait, mode, sync, key); | |
206 | } | |
207 | ||
208 | static int pollwake(wait_queue_t *wait, unsigned mode, int sync, void *key) | |
209 | { | |
210 | struct poll_table_entry *entry; | |
211 | ||
212 | entry = container_of(wait, struct poll_table_entry, wait); | |
213 | if (key && !((unsigned long)key & entry->key)) | |
214 | return 0; | |
215 | return __pollwake(wait, mode, sync, key); | |
216 | } | |
217 | ||
218 | /* Add a new entry */ | |
219 | static void __pollwait(struct file *filp, wait_queue_head_t *wait_address, | |
220 | poll_table *p) | |
221 | { | |
222 | struct poll_wqueues *pwq = container_of(p, struct poll_wqueues, pt); | |
223 | struct poll_table_entry *entry = poll_get_entry(pwq); | |
224 | if (!entry) | |
225 | return; | |
226 | entry->filp = get_file(filp); | |
227 | entry->wait_address = wait_address; | |
228 | entry->key = p->_key; | |
229 | init_waitqueue_func_entry(&entry->wait, pollwake); | |
230 | entry->wait.private = pwq; | |
231 | add_wait_queue(wait_address, &entry->wait); | |
232 | } | |
233 | ||
234 | int poll_schedule_timeout(struct poll_wqueues *pwq, int state, | |
235 | ktime_t *expires, unsigned long slack) | |
236 | { | |
237 | int rc = -EINTR; | |
238 | ||
239 | set_current_state(state); | |
240 | if (!pwq->triggered) | |
241 | rc = freezable_schedule_hrtimeout_range(expires, slack, | |
242 | HRTIMER_MODE_ABS); | |
243 | __set_current_state(TASK_RUNNING); | |
244 | ||
245 | /* | |
246 | * Prepare for the next iteration. | |
247 | * | |
248 | * The following set_mb() serves two purposes. First, it's | |
249 | * the counterpart rmb of the wmb in pollwake() such that data | |
250 | * written before wake up is always visible after wake up. | |
251 | * Second, the full barrier guarantees that triggered clearing | |
252 | * doesn't pass event check of the next iteration. Note that | |
253 | * this problem doesn't exist for the first iteration as | |
254 | * add_wait_queue() has full barrier semantics. | |
255 | */ | |
256 | set_mb(pwq->triggered, 0); | |
257 | ||
258 | return rc; | |
259 | } | |
260 | EXPORT_SYMBOL(poll_schedule_timeout); | |
261 | ||
262 | /** | |
263 | * poll_select_set_timeout - helper function to setup the timeout value | |
264 | * @to: pointer to timespec variable for the final timeout | |
265 | * @sec: seconds (from user space) | |
266 | * @nsec: nanoseconds (from user space) | |
267 | * | |
268 | * Note, we do not use a timespec for the user space value here, That | |
269 | * way we can use the function for timeval and compat interfaces as well. | |
270 | * | |
271 | * Returns -EINVAL if sec/nsec are not normalized. Otherwise 0. | |
272 | */ | |
273 | int poll_select_set_timeout(struct timespec *to, long sec, long nsec) | |
274 | { | |
275 | struct timespec ts = {.tv_sec = sec, .tv_nsec = nsec}; | |
276 | ||
277 | if (!timespec_valid(&ts)) | |
278 | return -EINVAL; | |
279 | ||
280 | /* Optimize for the zero timeout value here */ | |
281 | if (!sec && !nsec) { | |
282 | to->tv_sec = to->tv_nsec = 0; | |
283 | } else { | |
284 | ktime_get_ts(to); | |
285 | *to = timespec_add_safe(*to, ts); | |
286 | } | |
287 | return 0; | |
288 | } | |
289 | ||
290 | static int poll_select_copy_remaining(struct timespec *end_time, void __user *p, | |
291 | int timeval, int ret) | |
292 | { | |
293 | struct timespec rts; | |
294 | struct timeval rtv; | |
295 | ||
296 | if (!p) | |
297 | return ret; | |
298 | ||
299 | if (current->personality & STICKY_TIMEOUTS) | |
300 | goto sticky; | |
301 | ||
302 | /* No update for zero timeout */ | |
303 | if (!end_time->tv_sec && !end_time->tv_nsec) | |
304 | return ret; | |
305 | ||
306 | ktime_get_ts(&rts); | |
307 | rts = timespec_sub(*end_time, rts); | |
308 | if (rts.tv_sec < 0) | |
309 | rts.tv_sec = rts.tv_nsec = 0; | |
310 | ||
311 | if (timeval) { | |
312 | if (sizeof(rtv) > sizeof(rtv.tv_sec) + sizeof(rtv.tv_usec)) | |
313 | memset(&rtv, 0, sizeof(rtv)); | |
314 | rtv.tv_sec = rts.tv_sec; | |
315 | rtv.tv_usec = rts.tv_nsec / NSEC_PER_USEC; | |
316 | ||
317 | if (!copy_to_user(p, &rtv, sizeof(rtv))) | |
318 | return ret; | |
319 | ||
320 | } else if (!copy_to_user(p, &rts, sizeof(rts))) | |
321 | return ret; | |
322 | ||
323 | /* | |
324 | * If an application puts its timeval in read-only memory, we | |
325 | * don't want the Linux-specific update to the timeval to | |
326 | * cause a fault after the select has completed | |
327 | * successfully. However, because we're not updating the | |
328 | * timeval, we can't restart the system call. | |
329 | */ | |
330 | ||
331 | sticky: | |
332 | if (ret == -ERESTARTNOHAND) | |
333 | ret = -EINTR; | |
334 | return ret; | |
335 | } | |
336 | ||
337 | #define FDS_IN(fds, n) (fds->in + n) | |
338 | #define FDS_OUT(fds, n) (fds->out + n) | |
339 | #define FDS_EX(fds, n) (fds->ex + n) | |
340 | ||
341 | #define BITS(fds, n) (*FDS_IN(fds, n)|*FDS_OUT(fds, n)|*FDS_EX(fds, n)) | |
342 | ||
343 | static int max_select_fd(unsigned long n, fd_set_bits *fds) | |
344 | { | |
345 | unsigned long *open_fds; | |
346 | unsigned long set; | |
347 | int max; | |
348 | struct fdtable *fdt; | |
349 | ||
350 | /* handle last in-complete long-word first */ | |
351 | set = ~(~0UL << (n & (BITS_PER_LONG-1))); | |
352 | n /= BITS_PER_LONG; | |
353 | fdt = files_fdtable(current->files); | |
354 | open_fds = fdt->open_fds + n; | |
355 | max = 0; | |
356 | if (set) { | |
357 | set &= BITS(fds, n); | |
358 | if (set) { | |
359 | if (!(set & ~*open_fds)) | |
360 | goto get_max; | |
361 | return -EBADF; | |
362 | } | |
363 | } | |
364 | while (n) { | |
365 | open_fds--; | |
366 | n--; | |
367 | set = BITS(fds, n); | |
368 | if (!set) | |
369 | continue; | |
370 | if (set & ~*open_fds) | |
371 | return -EBADF; | |
372 | if (max) | |
373 | continue; | |
374 | get_max: | |
375 | do { | |
376 | max++; | |
377 | set >>= 1; | |
378 | } while (set); | |
379 | max += n * BITS_PER_LONG; | |
380 | } | |
381 | ||
382 | return max; | |
383 | } | |
384 | ||
385 | #define POLLIN_SET (POLLRDNORM | POLLRDBAND | POLLIN | POLLHUP | POLLERR) | |
386 | #define POLLOUT_SET (POLLWRBAND | POLLWRNORM | POLLOUT | POLLERR) | |
387 | #define POLLEX_SET (POLLPRI) | |
388 | ||
389 | static inline void wait_key_set(poll_table *wait, unsigned long in, | |
390 | unsigned long out, unsigned long bit, | |
391 | unsigned int ll_flag) | |
392 | { | |
393 | wait->_key = POLLEX_SET | ll_flag; | |
394 | if (in & bit) | |
395 | wait->_key |= POLLIN_SET; | |
396 | if (out & bit) | |
397 | wait->_key |= POLLOUT_SET; | |
398 | } | |
399 | ||
400 | int do_select(int n, fd_set_bits *fds, struct timespec *end_time) | |
401 | { | |
402 | ktime_t expire, *to = NULL; | |
403 | struct poll_wqueues table; | |
404 | poll_table *wait; | |
405 | int retval, i, timed_out = 0; | |
406 | unsigned long slack = 0; | |
407 | unsigned int busy_flag = net_busy_loop_on() ? POLL_BUSY_LOOP : 0; | |
408 | unsigned long busy_end = 0; | |
409 | ||
410 | rcu_read_lock(); | |
411 | retval = max_select_fd(n, fds); | |
412 | rcu_read_unlock(); | |
413 | ||
414 | if (retval < 0) | |
415 | return retval; | |
416 | n = retval; | |
417 | ||
418 | poll_initwait(&table); | |
419 | wait = &table.pt; | |
420 | if (end_time && !end_time->tv_sec && !end_time->tv_nsec) { | |
421 | wait->_qproc = NULL; | |
422 | timed_out = 1; | |
423 | } | |
424 | ||
425 | if (end_time && !timed_out) | |
426 | slack = select_estimate_accuracy(end_time); | |
427 | ||
428 | retval = 0; | |
429 | for (;;) { | |
430 | unsigned long *rinp, *routp, *rexp, *inp, *outp, *exp; | |
431 | bool can_busy_loop = false; | |
432 | ||
433 | inp = fds->in; outp = fds->out; exp = fds->ex; | |
434 | rinp = fds->res_in; routp = fds->res_out; rexp = fds->res_ex; | |
435 | ||
436 | for (i = 0; i < n; ++rinp, ++routp, ++rexp) { | |
437 | unsigned long in, out, ex, all_bits, bit = 1, mask, j; | |
438 | unsigned long res_in = 0, res_out = 0, res_ex = 0; | |
439 | ||
440 | in = *inp++; out = *outp++; ex = *exp++; | |
441 | all_bits = in | out | ex; | |
442 | if (all_bits == 0) { | |
443 | i += BITS_PER_LONG; | |
444 | continue; | |
445 | } | |
446 | ||
447 | for (j = 0; j < BITS_PER_LONG; ++j, ++i, bit <<= 1) { | |
448 | struct fd f; | |
449 | if (i >= n) | |
450 | break; | |
451 | if (!(bit & all_bits)) | |
452 | continue; | |
453 | f = fdget(i); | |
454 | if (f.file) { | |
455 | const struct file_operations *f_op; | |
456 | f_op = f.file->f_op; | |
457 | mask = DEFAULT_POLLMASK; | |
458 | if (f_op && f_op->poll) { | |
459 | wait_key_set(wait, in, out, | |
460 | bit, busy_flag); | |
461 | mask = (*f_op->poll)(f.file, wait); | |
462 | } | |
463 | fdput(f); | |
464 | if ((mask & POLLIN_SET) && (in & bit)) { | |
465 | res_in |= bit; | |
466 | retval++; | |
467 | wait->_qproc = NULL; | |
468 | } | |
469 | if ((mask & POLLOUT_SET) && (out & bit)) { | |
470 | res_out |= bit; | |
471 | retval++; | |
472 | wait->_qproc = NULL; | |
473 | } | |
474 | if ((mask & POLLEX_SET) && (ex & bit)) { | |
475 | res_ex |= bit; | |
476 | retval++; | |
477 | wait->_qproc = NULL; | |
478 | } | |
479 | /* got something, stop busy polling */ | |
480 | if (retval) { | |
481 | can_busy_loop = false; | |
482 | busy_flag = 0; | |
483 | ||
484 | /* | |
485 | * only remember a returned | |
486 | * POLL_BUSY_LOOP if we asked for it | |
487 | */ | |
488 | } else if (busy_flag & mask) | |
489 | can_busy_loop = true; | |
490 | ||
491 | } | |
492 | } | |
493 | if (res_in) | |
494 | *rinp = res_in; | |
495 | if (res_out) | |
496 | *routp = res_out; | |
497 | if (res_ex) | |
498 | *rexp = res_ex; | |
499 | cond_resched(); | |
500 | } | |
501 | wait->_qproc = NULL; | |
502 | if (retval || timed_out || signal_pending(current)) | |
503 | break; | |
504 | if (table.error) { | |
505 | retval = table.error; | |
506 | break; | |
507 | } | |
508 | ||
509 | /* only if found POLL_BUSY_LOOP sockets && not out of time */ | |
510 | if (can_busy_loop && !need_resched()) { | |
511 | if (!busy_end) { | |
512 | busy_end = busy_loop_end_time(); | |
513 | continue; | |
514 | } | |
515 | if (!busy_loop_timeout(busy_end)) | |
516 | continue; | |
517 | } | |
518 | busy_flag = 0; | |
519 | ||
520 | /* | |
521 | * If this is the first loop and we have a timeout | |
522 | * given, then we convert to ktime_t and set the to | |
523 | * pointer to the expiry value. | |
524 | */ | |
525 | if (end_time && !to) { | |
526 | expire = timespec_to_ktime(*end_time); | |
527 | to = &expire; | |
528 | } | |
529 | ||
530 | if (!poll_schedule_timeout(&table, TASK_INTERRUPTIBLE, | |
531 | to, slack)) | |
532 | timed_out = 1; | |
533 | } | |
534 | ||
535 | poll_freewait(&table); | |
536 | ||
537 | return retval; | |
538 | } | |
539 | ||
540 | /* | |
541 | * We can actually return ERESTARTSYS instead of EINTR, but I'd | |
542 | * like to be certain this leads to no problems. So I return | |
543 | * EINTR just for safety. | |
544 | * | |
545 | * Update: ERESTARTSYS breaks at least the xview clock binary, so | |
546 | * I'm trying ERESTARTNOHAND which restart only when you want to. | |
547 | */ | |
548 | int core_sys_select(int n, fd_set __user *inp, fd_set __user *outp, | |
549 | fd_set __user *exp, struct timespec *end_time) | |
550 | { | |
551 | fd_set_bits fds; | |
552 | void *bits; | |
553 | int ret, max_fds; | |
554 | unsigned int size; | |
555 | struct fdtable *fdt; | |
556 | /* Allocate small arguments on the stack to save memory and be faster */ | |
557 | long stack_fds[SELECT_STACK_ALLOC/sizeof(long)]; | |
558 | ||
559 | ret = -EINVAL; | |
560 | if (n < 0) | |
561 | goto out_nofds; | |
562 | ||
563 | /* max_fds can increase, so grab it once to avoid race */ | |
564 | rcu_read_lock(); | |
565 | fdt = files_fdtable(current->files); | |
566 | max_fds = fdt->max_fds; | |
567 | rcu_read_unlock(); | |
568 | if (n > max_fds) | |
569 | n = max_fds; | |
570 | ||
571 | /* | |
572 | * We need 6 bitmaps (in/out/ex for both incoming and outgoing), | |
573 | * since we used fdset we need to allocate memory in units of | |
574 | * long-words. | |
575 | */ | |
576 | size = FDS_BYTES(n); | |
577 | bits = stack_fds; | |
578 | if (size > sizeof(stack_fds) / 6) { | |
579 | /* Not enough space in on-stack array; must use kmalloc */ | |
580 | ret = -ENOMEM; | |
581 | bits = kmalloc(6 * size, GFP_KERNEL); | |
582 | if (!bits) | |
583 | goto out_nofds; | |
584 | } | |
585 | fds.in = bits; | |
586 | fds.out = bits + size; | |
587 | fds.ex = bits + 2*size; | |
588 | fds.res_in = bits + 3*size; | |
589 | fds.res_out = bits + 4*size; | |
590 | fds.res_ex = bits + 5*size; | |
591 | ||
592 | if ((ret = get_fd_set(n, inp, fds.in)) || | |
593 | (ret = get_fd_set(n, outp, fds.out)) || | |
594 | (ret = get_fd_set(n, exp, fds.ex))) | |
595 | goto out; | |
596 | zero_fd_set(n, fds.res_in); | |
597 | zero_fd_set(n, fds.res_out); | |
598 | zero_fd_set(n, fds.res_ex); | |
599 | ||
600 | ret = do_select(n, &fds, end_time); | |
601 | ||
602 | if (ret < 0) | |
603 | goto out; | |
604 | if (!ret) { | |
605 | ret = -ERESTARTNOHAND; | |
606 | if (signal_pending(current)) | |
607 | goto out; | |
608 | ret = 0; | |
609 | } | |
610 | ||
611 | if (set_fd_set(n, inp, fds.res_in) || | |
612 | set_fd_set(n, outp, fds.res_out) || | |
613 | set_fd_set(n, exp, fds.res_ex)) | |
614 | ret = -EFAULT; | |
615 | ||
616 | out: | |
617 | if (bits != stack_fds) | |
618 | kfree(bits); | |
619 | out_nofds: | |
620 | return ret; | |
621 | } | |
622 | ||
623 | SYSCALL_DEFINE5(select, int, n, fd_set __user *, inp, fd_set __user *, outp, | |
624 | fd_set __user *, exp, struct timeval __user *, tvp) | |
625 | { | |
626 | struct timespec end_time, *to = NULL; | |
627 | struct timeval tv; | |
628 | int ret; | |
629 | ||
630 | if (tvp) { | |
631 | if (copy_from_user(&tv, tvp, sizeof(tv))) | |
632 | return -EFAULT; | |
633 | ||
634 | to = &end_time; | |
635 | if (poll_select_set_timeout(to, | |
636 | tv.tv_sec + (tv.tv_usec / USEC_PER_SEC), | |
637 | (tv.tv_usec % USEC_PER_SEC) * NSEC_PER_USEC)) | |
638 | return -EINVAL; | |
639 | } | |
640 | ||
641 | ret = core_sys_select(n, inp, outp, exp, to); | |
642 | ret = poll_select_copy_remaining(&end_time, tvp, 1, ret); | |
643 | ||
644 | return ret; | |
645 | } | |
646 | ||
647 | static long do_pselect(int n, fd_set __user *inp, fd_set __user *outp, | |
648 | fd_set __user *exp, struct timespec __user *tsp, | |
649 | const sigset_t __user *sigmask, size_t sigsetsize) | |
650 | { | |
651 | sigset_t ksigmask, sigsaved; | |
652 | struct timespec ts, end_time, *to = NULL; | |
653 | int ret; | |
654 | ||
655 | if (tsp) { | |
656 | if (copy_from_user(&ts, tsp, sizeof(ts))) | |
657 | return -EFAULT; | |
658 | ||
659 | to = &end_time; | |
660 | if (poll_select_set_timeout(to, ts.tv_sec, ts.tv_nsec)) | |
661 | return -EINVAL; | |
662 | } | |
663 | ||
664 | if (sigmask) { | |
665 | /* XXX: Don't preclude handling different sized sigset_t's. */ | |
666 | if (sigsetsize != sizeof(sigset_t)) | |
667 | return -EINVAL; | |
668 | if (copy_from_user(&ksigmask, sigmask, sizeof(ksigmask))) | |
669 | return -EFAULT; | |
670 | ||
671 | sigdelsetmask(&ksigmask, sigmask(SIGKILL)|sigmask(SIGSTOP)); | |
672 | sigprocmask(SIG_SETMASK, &ksigmask, &sigsaved); | |
673 | } | |
674 | ||
675 | ret = core_sys_select(n, inp, outp, exp, to); | |
676 | ret = poll_select_copy_remaining(&end_time, tsp, 0, ret); | |
677 | ||
678 | if (ret == -ERESTARTNOHAND) { | |
679 | /* | |
680 | * Don't restore the signal mask yet. Let do_signal() deliver | |
681 | * the signal on the way back to userspace, before the signal | |
682 | * mask is restored. | |
683 | */ | |
684 | if (sigmask) { | |
685 | memcpy(¤t->saved_sigmask, &sigsaved, | |
686 | sizeof(sigsaved)); | |
687 | set_restore_sigmask(); | |
688 | } | |
689 | } else if (sigmask) | |
690 | sigprocmask(SIG_SETMASK, &sigsaved, NULL); | |
691 | ||
692 | return ret; | |
693 | } | |
694 | ||
695 | /* | |
696 | * Most architectures can't handle 7-argument syscalls. So we provide a | |
697 | * 6-argument version where the sixth argument is a pointer to a structure | |
698 | * which has a pointer to the sigset_t itself followed by a size_t containing | |
699 | * the sigset size. | |
700 | */ | |
701 | SYSCALL_DEFINE6(pselect6, int, n, fd_set __user *, inp, fd_set __user *, outp, | |
702 | fd_set __user *, exp, struct timespec __user *, tsp, | |
703 | void __user *, sig) | |
704 | { | |
705 | size_t sigsetsize = 0; | |
706 | sigset_t __user *up = NULL; | |
707 | ||
708 | if (sig) { | |
709 | if (!access_ok(VERIFY_READ, sig, sizeof(void *)+sizeof(size_t)) | |
710 | || __get_user(up, (sigset_t __user * __user *)sig) | |
711 | || __get_user(sigsetsize, | |
712 | (size_t __user *)(sig+sizeof(void *)))) | |
713 | return -EFAULT; | |
714 | } | |
715 | ||
716 | return do_pselect(n, inp, outp, exp, tsp, up, sigsetsize); | |
717 | } | |
718 | ||
719 | #ifdef __ARCH_WANT_SYS_OLD_SELECT | |
720 | struct sel_arg_struct { | |
721 | unsigned long n; | |
722 | fd_set __user *inp, *outp, *exp; | |
723 | struct timeval __user *tvp; | |
724 | }; | |
725 | ||
726 | SYSCALL_DEFINE1(old_select, struct sel_arg_struct __user *, arg) | |
727 | { | |
728 | struct sel_arg_struct a; | |
729 | ||
730 | if (copy_from_user(&a, arg, sizeof(a))) | |
731 | return -EFAULT; | |
732 | return sys_select(a.n, a.inp, a.outp, a.exp, a.tvp); | |
733 | } | |
734 | #endif | |
735 | ||
736 | struct poll_list { | |
737 | struct poll_list *next; | |
738 | int len; | |
739 | struct pollfd entries[0]; | |
740 | }; | |
741 | ||
742 | #define POLLFD_PER_PAGE ((PAGE_SIZE-sizeof(struct poll_list)) / sizeof(struct pollfd)) | |
743 | ||
744 | /* | |
745 | * Fish for pollable events on the pollfd->fd file descriptor. We're only | |
746 | * interested in events matching the pollfd->events mask, and the result | |
747 | * matching that mask is both recorded in pollfd->revents and returned. The | |
748 | * pwait poll_table will be used by the fd-provided poll handler for waiting, | |
749 | * if pwait->_qproc is non-NULL. | |
750 | */ | |
751 | static inline unsigned int do_pollfd(struct pollfd *pollfd, poll_table *pwait, | |
752 | bool *can_busy_poll, | |
753 | unsigned int busy_flag) | |
754 | { | |
755 | unsigned int mask; | |
756 | int fd; | |
757 | ||
758 | mask = 0; | |
759 | fd = pollfd->fd; | |
760 | if (fd >= 0) { | |
761 | struct fd f = fdget(fd); | |
762 | mask = POLLNVAL; | |
763 | if (f.file) { | |
764 | mask = DEFAULT_POLLMASK; | |
765 | if (f.file->f_op && f.file->f_op->poll) { | |
766 | pwait->_key = pollfd->events|POLLERR|POLLHUP; | |
767 | pwait->_key |= busy_flag; | |
768 | mask = f.file->f_op->poll(f.file, pwait); | |
769 | if (mask & busy_flag) | |
770 | *can_busy_poll = true; | |
771 | } | |
772 | /* Mask out unneeded events. */ | |
773 | mask &= pollfd->events | POLLERR | POLLHUP; | |
774 | fdput(f); | |
775 | } | |
776 | } | |
777 | pollfd->revents = mask; | |
778 | ||
779 | return mask; | |
780 | } | |
781 | ||
782 | static int do_poll(unsigned int nfds, struct poll_list *list, | |
783 | struct poll_wqueues *wait, struct timespec *end_time) | |
784 | { | |
785 | poll_table* pt = &wait->pt; | |
786 | ktime_t expire, *to = NULL; | |
787 | int timed_out = 0, count = 0; | |
788 | unsigned long slack = 0; | |
789 | unsigned int busy_flag = net_busy_loop_on() ? POLL_BUSY_LOOP : 0; | |
790 | unsigned long busy_end = 0; | |
791 | ||
792 | /* Optimise the no-wait case */ | |
793 | if (end_time && !end_time->tv_sec && !end_time->tv_nsec) { | |
794 | pt->_qproc = NULL; | |
795 | timed_out = 1; | |
796 | } | |
797 | ||
798 | if (end_time && !timed_out) | |
799 | slack = select_estimate_accuracy(end_time); | |
800 | ||
801 | for (;;) { | |
802 | struct poll_list *walk; | |
803 | bool can_busy_loop = false; | |
804 | ||
805 | for (walk = list; walk != NULL; walk = walk->next) { | |
806 | struct pollfd * pfd, * pfd_end; | |
807 | ||
808 | pfd = walk->entries; | |
809 | pfd_end = pfd + walk->len; | |
810 | for (; pfd != pfd_end; pfd++) { | |
811 | /* | |
812 | * Fish for events. If we found one, record it | |
813 | * and kill poll_table->_qproc, so we don't | |
814 | * needlessly register any other waiters after | |
815 | * this. They'll get immediately deregistered | |
816 | * when we break out and return. | |
817 | */ | |
818 | if (do_pollfd(pfd, pt, &can_busy_loop, | |
819 | busy_flag)) { | |
820 | count++; | |
821 | pt->_qproc = NULL; | |
822 | /* found something, stop busy polling */ | |
823 | busy_flag = 0; | |
824 | can_busy_loop = false; | |
825 | } | |
826 | } | |
827 | } | |
828 | /* | |
829 | * All waiters have already been registered, so don't provide | |
830 | * a poll_table->_qproc to them on the next loop iteration. | |
831 | */ | |
832 | pt->_qproc = NULL; | |
833 | if (!count) { | |
834 | count = wait->error; | |
835 | if (signal_pending(current)) | |
836 | count = -EINTR; | |
837 | } | |
838 | if (count || timed_out) | |
839 | break; | |
840 | ||
841 | /* only if found POLL_BUSY_LOOP sockets && not out of time */ | |
842 | if (can_busy_loop && !need_resched()) { | |
843 | if (!busy_end) { | |
844 | busy_end = busy_loop_end_time(); | |
845 | continue; | |
846 | } | |
847 | if (!busy_loop_timeout(busy_end)) | |
848 | continue; | |
849 | } | |
850 | busy_flag = 0; | |
851 | ||
852 | /* | |
853 | * If this is the first loop and we have a timeout | |
854 | * given, then we convert to ktime_t and set the to | |
855 | * pointer to the expiry value. | |
856 | */ | |
857 | if (end_time && !to) { | |
858 | expire = timespec_to_ktime(*end_time); | |
859 | to = &expire; | |
860 | } | |
861 | ||
862 | if (!poll_schedule_timeout(wait, TASK_INTERRUPTIBLE, to, slack)) | |
863 | timed_out = 1; | |
864 | } | |
865 | return count; | |
866 | } | |
867 | ||
868 | #define N_STACK_PPS ((sizeof(stack_pps) - sizeof(struct poll_list)) / \ | |
869 | sizeof(struct pollfd)) | |
870 | ||
871 | int do_sys_poll(struct pollfd __user *ufds, unsigned int nfds, | |
872 | struct timespec *end_time) | |
873 | { | |
874 | struct poll_wqueues table; | |
875 | int err = -EFAULT, fdcount, len, size; | |
876 | /* Allocate small arguments on the stack to save memory and be | |
877 | faster - use long to make sure the buffer is aligned properly | |
878 | on 64 bit archs to avoid unaligned access */ | |
879 | long stack_pps[POLL_STACK_ALLOC/sizeof(long)]; | |
880 | struct poll_list *const head = (struct poll_list *)stack_pps; | |
881 | struct poll_list *walk = head; | |
882 | unsigned long todo = nfds; | |
883 | ||
884 | if (nfds > rlimit(RLIMIT_NOFILE)) | |
885 | return -EINVAL; | |
886 | ||
887 | len = min_t(unsigned int, nfds, N_STACK_PPS); | |
888 | for (;;) { | |
889 | walk->next = NULL; | |
890 | walk->len = len; | |
891 | if (!len) | |
892 | break; | |
893 | ||
894 | if (copy_from_user(walk->entries, ufds + nfds-todo, | |
895 | sizeof(struct pollfd) * walk->len)) | |
896 | goto out_fds; | |
897 | ||
898 | todo -= walk->len; | |
899 | if (!todo) | |
900 | break; | |
901 | ||
902 | len = min(todo, POLLFD_PER_PAGE); | |
903 | size = sizeof(struct poll_list) + sizeof(struct pollfd) * len; | |
904 | walk = walk->next = kmalloc(size, GFP_KERNEL); | |
905 | if (!walk) { | |
906 | err = -ENOMEM; | |
907 | goto out_fds; | |
908 | } | |
909 | } | |
910 | ||
911 | poll_initwait(&table); | |
912 | fdcount = do_poll(nfds, head, &table, end_time); | |
913 | poll_freewait(&table); | |
914 | ||
915 | for (walk = head; walk; walk = walk->next) { | |
916 | struct pollfd *fds = walk->entries; | |
917 | int j; | |
918 | ||
919 | for (j = 0; j < walk->len; j++, ufds++) | |
920 | if (__put_user(fds[j].revents, &ufds->revents)) | |
921 | goto out_fds; | |
922 | } | |
923 | ||
924 | err = fdcount; | |
925 | out_fds: | |
926 | walk = head->next; | |
927 | while (walk) { | |
928 | struct poll_list *pos = walk; | |
929 | walk = walk->next; | |
930 | kfree(pos); | |
931 | } | |
932 | ||
933 | return err; | |
934 | } | |
935 | ||
936 | static long do_restart_poll(struct restart_block *restart_block) | |
937 | { | |
938 | struct pollfd __user *ufds = restart_block->poll.ufds; | |
939 | int nfds = restart_block->poll.nfds; | |
940 | struct timespec *to = NULL, end_time; | |
941 | int ret; | |
942 | ||
943 | if (restart_block->poll.has_timeout) { | |
944 | end_time.tv_sec = restart_block->poll.tv_sec; | |
945 | end_time.tv_nsec = restart_block->poll.tv_nsec; | |
946 | to = &end_time; | |
947 | } | |
948 | ||
949 | ret = do_sys_poll(ufds, nfds, to); | |
950 | ||
951 | if (ret == -EINTR) { | |
952 | restart_block->fn = do_restart_poll; | |
953 | ret = -ERESTART_RESTARTBLOCK; | |
954 | } | |
955 | return ret; | |
956 | } | |
957 | ||
958 | SYSCALL_DEFINE3(poll, struct pollfd __user *, ufds, unsigned int, nfds, | |
959 | int, timeout_msecs) | |
960 | { | |
961 | struct timespec end_time, *to = NULL; | |
962 | int ret; | |
963 | ||
964 | if (timeout_msecs >= 0) { | |
965 | to = &end_time; | |
966 | poll_select_set_timeout(to, timeout_msecs / MSEC_PER_SEC, | |
967 | NSEC_PER_MSEC * (timeout_msecs % MSEC_PER_SEC)); | |
968 | } | |
969 | ||
970 | ret = do_sys_poll(ufds, nfds, to); | |
971 | ||
972 | if (ret == -EINTR) { | |
973 | struct restart_block *restart_block; | |
974 | ||
975 | restart_block = ¤t_thread_info()->restart_block; | |
976 | restart_block->fn = do_restart_poll; | |
977 | restart_block->poll.ufds = ufds; | |
978 | restart_block->poll.nfds = nfds; | |
979 | ||
980 | if (timeout_msecs >= 0) { | |
981 | restart_block->poll.tv_sec = end_time.tv_sec; | |
982 | restart_block->poll.tv_nsec = end_time.tv_nsec; | |
983 | restart_block->poll.has_timeout = 1; | |
984 | } else | |
985 | restart_block->poll.has_timeout = 0; | |
986 | ||
987 | ret = -ERESTART_RESTARTBLOCK; | |
988 | } | |
989 | return ret; | |
990 | } | |
991 | ||
992 | SYSCALL_DEFINE5(ppoll, struct pollfd __user *, ufds, unsigned int, nfds, | |
993 | struct timespec __user *, tsp, const sigset_t __user *, sigmask, | |
994 | size_t, sigsetsize) | |
995 | { | |
996 | sigset_t ksigmask, sigsaved; | |
997 | struct timespec ts, end_time, *to = NULL; | |
998 | int ret; | |
999 | ||
1000 | if (tsp) { | |
1001 | if (copy_from_user(&ts, tsp, sizeof(ts))) | |
1002 | return -EFAULT; | |
1003 | ||
1004 | to = &end_time; | |
1005 | if (poll_select_set_timeout(to, ts.tv_sec, ts.tv_nsec)) | |
1006 | return -EINVAL; | |
1007 | } | |
1008 | ||
1009 | if (sigmask) { | |
1010 | /* XXX: Don't preclude handling different sized sigset_t's. */ | |
1011 | if (sigsetsize != sizeof(sigset_t)) | |
1012 | return -EINVAL; | |
1013 | if (copy_from_user(&ksigmask, sigmask, sizeof(ksigmask))) | |
1014 | return -EFAULT; | |
1015 | ||
1016 | sigdelsetmask(&ksigmask, sigmask(SIGKILL)|sigmask(SIGSTOP)); | |
1017 | sigprocmask(SIG_SETMASK, &ksigmask, &sigsaved); | |
1018 | } | |
1019 | ||
1020 | ret = do_sys_poll(ufds, nfds, to); | |
1021 | ||
1022 | /* We can restart this syscall, usually */ | |
1023 | if (ret == -EINTR) { | |
1024 | /* | |
1025 | * Don't restore the signal mask yet. Let do_signal() deliver | |
1026 | * the signal on the way back to userspace, before the signal | |
1027 | * mask is restored. | |
1028 | */ | |
1029 | if (sigmask) { | |
1030 | memcpy(¤t->saved_sigmask, &sigsaved, | |
1031 | sizeof(sigsaved)); | |
1032 | set_restore_sigmask(); | |
1033 | } | |
1034 | ret = -ERESTARTNOHAND; | |
1035 | } else if (sigmask) | |
1036 | sigprocmask(SIG_SETMASK, &sigsaved, NULL); | |
1037 | ||
1038 | ret = poll_select_copy_remaining(&end_time, tsp, 0, ret); | |
1039 | ||
1040 | return ret; | |
1041 | } |