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