Merge branch 'next' of git://git.monstr.eu/linux-2.6-microblaze
[platform/adaptation/renesas_rcar/renesas_kernel.git] / fs / select.c
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/ll_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(&current->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 = &current_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(&current->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 }