fs/fcntl.c

   1 /*
   2  *  linux/fs/fcntl.c
   3  *
   4  *  Copyright (C) 1991, 1992  Linus Torvalds
   5  */
   6
   7 #include <linux/syscalls.h>
   8 #include <linux/init.h>
   9 #include <linux/mm.h>
  10 #include <linux/fs.h>
  11 #include <linux/file.h>
  12 #include <linux/fdtable.h>
  13 #include <linux/capability.h>
  14 #include <linux/dnotify.h>
  15 #include <linux/slab.h>
  16 #include <linux/module.h>
  17 #include <linux/pipe_fs_i.h>
  18 #include <linux/security.h>
  19 #include <linux/ptrace.h>
  20 #include <linux/signal.h>
  21 #include <linux/rcupdate.h>
  22 #include <linux/pid_namespace.h>
  23 #include <linux/user_namespace.h>
  24 #include <linux/shmem_fs.h>
  25
  26 #include <asm/poll.h>
  27 #include <asm/siginfo.h>
  28 #include <asm/uaccess.h>
  29
  30 #define SETFL_MASK (O_APPEND | O_NONBLOCK | O_NDELAY | O_DIRECT | O_NOATIME)
  31
  32 static int setfl(int fd, struct file * filp, unsigned long arg)
  33 {
  34         struct inode * inode = file_inode(filp);
  35         int error = 0;
  36
  37         /*
  38          * O_APPEND cannot be cleared if the file is marked as append-only
  39          * and the file is open for write.
  40          */
  41         if (((arg ^ filp->f_flags) & O_APPEND) && IS_APPEND(inode))
  42                 return -EPERM;
  43
  44         /* O_NOATIME can only be set by the owner or superuser */
  45         if ((arg & O_NOATIME) && !(filp->f_flags & O_NOATIME))
  46                 if (!inode_owner_or_capable(inode))
  47                         return -EPERM;
  48
  49         /* required for strict SunOS emulation */
  50         if (O_NONBLOCK != O_NDELAY)
  51                if (arg & O_NDELAY)
  52                    arg |= O_NONBLOCK;
  53
  54         /* Pipe packetized mode is controlled by O_DIRECT flag */
  55         if (!S_ISFIFO(filp->f_inode->i_mode) && (arg & O_DIRECT)) {
  56                 if (!filp->f_mapping || !filp->f_mapping->a_ops ||
  57                         !filp->f_mapping->a_ops->direct_IO)
  58                                 return -EINVAL;
  59         }
  60
  61         if (filp->f_op->check_flags)
  62                 error = filp->f_op->check_flags(arg);
  63         if (error)
  64                 return error;
  65
  66         /*
  67          * ->fasync() is responsible for setting the FASYNC bit.
  68          */
  69         if (((arg ^ filp->f_flags) & FASYNC) && filp->f_op->fasync) {
  70                 error = filp->f_op->fasync(fd, filp, (arg & FASYNC) != 0);
  71                 if (error < 0)
  72                         goto out;
  73                 if (error > 0)
  74                         error = 0;
  75         }
  76         spin_lock(&filp->f_lock);
  77         filp->f_flags = (arg & SETFL_MASK) | (filp->f_flags & ~SETFL_MASK);
  78         spin_unlock(&filp->f_lock);
  79
  80  out:
  81         return error;
  82 }
  83
  84 static void f_modown(struct file *filp, struct pid *pid, enum pid_type type,
  85                      int force)
  86 {
  87         write_lock_irq(&filp->f_owner.lock);
  88         if (force || !filp->f_owner.pid) {
  89                 put_pid(filp->f_owner.pid);
  90                 filp->f_owner.pid = get_pid(pid);
  91                 filp->f_owner.pid_type = type;
  92
  93                 if (pid) {
  94                         const struct cred *cred = current_cred();
  95                         filp->f_owner.uid = cred->uid;
  96                         filp->f_owner.euid = cred->euid;
  97                 }
  98         }
  99         write_unlock_irq(&filp->f_owner.lock);
 100 }
 101
 102 void __f_setown(struct file *filp, struct pid *pid, enum pid_type type,
 103                 int force)
 104 {
 105         security_file_set_fowner(filp);
 106         f_modown(filp, pid, type, force);
 107 }
 108 EXPORT_SYMBOL(__f_setown);
 109
 110 void f_setown(struct file *filp, unsigned long arg, int force)
 111 {
 112         enum pid_type type;
 113         struct pid *pid;
 114         int who = arg;
 115         type = PIDTYPE_PID;
 116         if (who < 0) {
 117                 /* avoid overflow below */
 118                 if (who == INT_MIN)
 119                         return;
 120
 121                 type = PIDTYPE_PGID;
 122                 who = -who;
 123         }
 124         rcu_read_lock();
 125         pid = find_vpid(who);
 126         __f_setown(filp, pid, type, force);
 127         rcu_read_unlock();
 128 }
 129 EXPORT_SYMBOL(f_setown);
 130
 131 void f_delown(struct file *filp)
 132 {
 133         f_modown(filp, NULL, PIDTYPE_PID, 1);
 134 }
 135
 136 pid_t f_getown(struct file *filp)
 137 {
 138         pid_t pid;
 139         read_lock(&filp->f_owner.lock);
 140         pid = pid_vnr(filp->f_owner.pid);
 141         if (filp->f_owner.pid_type == PIDTYPE_PGID)
 142                 pid = -pid;
 143         read_unlock(&filp->f_owner.lock);
 144         return pid;
 145 }
 146
 147 static int f_setown_ex(struct file *filp, unsigned long arg)
 148 {
 149         struct f_owner_ex __user *owner_p = (void __user *)arg;
 150         struct f_owner_ex owner;
 151         struct pid *pid;
 152         int type;
 153         int ret;
 154
 155         ret = copy_from_user(&owner, owner_p, sizeof(owner));
 156         if (ret)
 157                 return -EFAULT;
 158
 159         switch (owner.type) {
 160         case F_OWNER_TID:
 161                 type = PIDTYPE_MAX;
 162                 break;
 163
 164         case F_OWNER_PID:
 165                 type = PIDTYPE_PID;
 166                 break;
 167
 168         case F_OWNER_PGRP:
 169                 type = PIDTYPE_PGID;
 170                 break;
 171
 172         default:
 173                 return -EINVAL;
 174         }
 175
 176         rcu_read_lock();
 177         pid = find_vpid(owner.pid);
 178         if (owner.pid && !pid)
 179                 ret = -ESRCH;
 180         else
 181                  __f_setown(filp, pid, type, 1);
 182         rcu_read_unlock();
 183
 184         return ret;
 185 }
 186
 187 static int f_getown_ex(struct file *filp, unsigned long arg)
 188 {
 189         struct f_owner_ex __user *owner_p = (void __user *)arg;
 190         struct f_owner_ex owner;
 191         int ret = 0;
 192
 193         read_lock(&filp->f_owner.lock);
 194         owner.pid = pid_vnr(filp->f_owner.pid);
 195         switch (filp->f_owner.pid_type) {
 196         case PIDTYPE_MAX:
 197                 owner.type = F_OWNER_TID;
 198                 break;
 199
 200         case PIDTYPE_PID:
 201                 owner.type = F_OWNER_PID;
 202                 break;
 203
 204         case PIDTYPE_PGID:
 205                 owner.type = F_OWNER_PGRP;
 206                 break;
 207
 208         default:
 209                 WARN_ON(1);
 210                 ret = -EINVAL;
 211                 break;
 212         }
 213         read_unlock(&filp->f_owner.lock);
 214
 215         if (!ret) {
 216                 ret = copy_to_user(owner_p, &owner, sizeof(owner));
 217                 if (ret)
 218                         ret = -EFAULT;
 219         }
 220         return ret;
 221 }
 222
 223 #ifdef CONFIG_CHECKPOINT_RESTORE
 224 static int f_getowner_uids(struct file *filp, unsigned long arg)
 225 {
 226         struct user_namespace *user_ns = current_user_ns();
 227         uid_t __user *dst = (void __user *)arg;
 228         uid_t src[2];
 229         int err;
 230
 231         read_lock(&filp->f_owner.lock);
 232         src[0] = from_kuid(user_ns, filp->f_owner.uid);
 233         src[1] = from_kuid(user_ns, filp->f_owner.euid);
 234         read_unlock(&filp->f_owner.lock);
 235
 236         err  = put_user(src[0], &dst[0]);
 237         err |= put_user(src[1], &dst[1]);
 238
 239         return err;
 240 }
 241 #else
 242 static int f_getowner_uids(struct file *filp, unsigned long arg)
 243 {
 244         return -EINVAL;
 245 }
 246 #endif
 247
 248 static long do_fcntl(int fd, unsigned int cmd, unsigned long arg,
 249                 struct file *filp)
 250 {
 251         long err = -EINVAL;
 252
 253         switch (cmd) {
 254         case F_DUPFD:
 255                 err = f_dupfd(arg, filp, 0);
 256                 break;
 257         case F_DUPFD_CLOEXEC:
 258                 err = f_dupfd(arg, filp, O_CLOEXEC);
 259                 break;
 260         case F_GETFD:
 261                 err = get_close_on_exec(fd) ? FD_CLOEXEC : 0;
 262                 break;
 263         case F_SETFD:
 264                 err = 0;
 265                 set_close_on_exec(fd, arg & FD_CLOEXEC);
 266                 break;
 267         case F_GETFL:
 268                 err = filp->f_flags;
 269                 break;
 270         case F_SETFL:
 271                 err = setfl(fd, filp, arg);
 272                 break;
 273 #if BITS_PER_LONG != 32
 274         /* 32-bit arches must use fcntl64() */
 275         case F_OFD_GETLK:
 276 #endif
 277         case F_GETLK:
 278                 err = fcntl_getlk(filp, cmd, (struct flock __user *) arg);
 279                 break;
 280 #if BITS_PER_LONG != 32
 281         /* 32-bit arches must use fcntl64() */
 282         case F_OFD_SETLK:
 283         case F_OFD_SETLKW:
 284 #endif
 285                 /* Fallthrough */
 286         case F_SETLK:
 287         case F_SETLKW:
 288                 err = fcntl_setlk(fd, filp, cmd, (struct flock __user *) arg);
 289                 break;
 290         case F_GETOWN:
 291                 /*
 292                  * XXX If f_owner is a process group, the
 293                  * negative return value will get converted
 294                  * into an error.  Oops.  If we keep the
 295                  * current syscall conventions, the only way
 296                  * to fix this will be in libc.
 297                  */
 298                 err = f_getown(filp);
 299                 force_successful_syscall_return();
 300                 break;
 301         case F_SETOWN:
 302                 f_setown(filp, arg, 1);
 303                 err = 0;
 304                 break;
 305         case F_GETOWN_EX:
 306                 err = f_getown_ex(filp, arg);
 307                 break;
 308         case F_SETOWN_EX:
 309                 err = f_setown_ex(filp, arg);
 310                 break;
 311         case F_GETOWNER_UIDS:
 312                 err = f_getowner_uids(filp, arg);
 313                 break;
 314         case F_GETSIG:
 315                 err = filp->f_owner.signum;
 316                 break;
 317         case F_SETSIG:
 318                 /* arg == 0 restores default behaviour. */
 319                 if (!valid_signal(arg)) {
 320                         break;
 321                 }
 322                 err = 0;
 323                 filp->f_owner.signum = arg;
 324                 break;
 325         case F_GETLEASE:
 326                 err = fcntl_getlease(filp);
 327                 break;
 328         case F_SETLEASE:
 329                 err = fcntl_setlease(fd, filp, arg);
 330                 break;
 331         case F_NOTIFY:
 332                 err = fcntl_dirnotify(fd, filp, arg);
 333                 break;
 334         case F_SETPIPE_SZ:
 335         case F_GETPIPE_SZ:
 336                 err = pipe_fcntl(filp, cmd, arg);
 337                 break;
 338         case F_ADD_SEALS:
 339         case F_GET_SEALS:
 340                 err = shmem_fcntl(filp, cmd, arg);
 341                 break;
 342         default:
 343                 break;
 344         }
 345         return err;
 346 }
 347
 348 static int check_fcntl_cmd(unsigned cmd)
 349 {
 350         switch (cmd) {
 351         case F_DUPFD:
 352         case F_DUPFD_CLOEXEC:
 353         case F_GETFD:
 354         case F_SETFD:
 355         case F_GETFL:
 356                 return 1;
 357         }
 358         return 0;
 359 }
 360
 361 SYSCALL_DEFINE3(fcntl, unsigned int, fd, unsigned int, cmd, unsigned long, arg)
 362 {
 363         struct fd f = fdget_raw(fd);
 364         long err = -EBADF;
 365
 366         if (!f.file)
 367                 goto out;
 368
 369         if (unlikely(f.file->f_mode & FMODE_PATH)) {
 370                 if (!check_fcntl_cmd(cmd))
 371                         goto out1;
 372         }
 373
 374         err = security_file_fcntl(f.file, cmd, arg);
 375         if (!err)
 376                 err = do_fcntl(fd, cmd, arg, f.file);
 377
 378 out1:
 379         fdput(f);
 380 out:
 381         return err;
 382 }
 383
 384 #if BITS_PER_LONG == 32
 385 SYSCALL_DEFINE3(fcntl64, unsigned int, fd, unsigned int, cmd,
 386                 unsigned long, arg)
 387 {
 388         struct fd f = fdget_raw(fd);
 389         long err = -EBADF;
 390
 391         if (!f.file)
 392                 goto out;
 393
 394         if (unlikely(f.file->f_mode & FMODE_PATH)) {
 395                 if (!check_fcntl_cmd(cmd))
 396                         goto out1;
 397         }
 398
 399         err = security_file_fcntl(f.file, cmd, arg);
 400         if (err)
 401                 goto out1;
 402
 403         switch (cmd) {
 404         case F_GETLK64:
 405         case F_OFD_GETLK:
 406                 err = fcntl_getlk64(f.file, cmd, (struct flock64 __user *) arg);
 407                 break;
 408         case F_SETLK64:
 409         case F_SETLKW64:
 410         case F_OFD_SETLK:
 411         case F_OFD_SETLKW:
 412                 err = fcntl_setlk64(fd, f.file, cmd,
 413                                 (struct flock64 __user *) arg);
 414                 break;
 415         default:
 416                 err = do_fcntl(fd, cmd, arg, f.file);
 417                 break;
 418         }
 419 out1:
 420         fdput(f);
 421 out:
 422         return err;
 423 }
 424 #endif
 425
 426 /* Table to convert sigio signal codes into poll band bitmaps */
 427
 428 static const long band_table[NSIGPOLL] = {
 429         POLLIN | POLLRDNORM,                    /* POLL_IN */
 430         POLLOUT | POLLWRNORM | POLLWRBAND,      /* POLL_OUT */
 431         POLLIN | POLLRDNORM | POLLMSG,          /* POLL_MSG */
 432         POLLERR,                                /* POLL_ERR */
 433         POLLPRI | POLLRDBAND,                   /* POLL_PRI */
 434         POLLHUP | POLLERR                       /* POLL_HUP */
 435 };
 436
 437 static inline int sigio_perm(struct task_struct *p,
 438                              struct fown_struct *fown, int sig)
 439 {
 440         const struct cred *cred;
 441         int ret;
 442
 443         rcu_read_lock();
 444         cred = __task_cred(p);
 445         ret = ((uid_eq(fown->euid, GLOBAL_ROOT_UID) ||
 446                 uid_eq(fown->euid, cred->suid) || uid_eq(fown->euid, cred->uid) ||
 447                 uid_eq(fown->uid,  cred->suid) || uid_eq(fown->uid,  cred->uid)) &&
 448                !security_file_send_sigiotask(p, fown, sig));
 449         rcu_read_unlock();
 450         return ret;
 451 }
 452
 453 static void send_sigio_to_task(struct task_struct *p,
 454                                struct fown_struct *fown,
 455                                int fd, int reason, int group)
 456 {
 457         /*
 458          * F_SETSIG can change ->signum lockless in parallel, make
 459          * sure we read it once and use the same value throughout.
 460          */
 461         int signum = ACCESS_ONCE(fown->signum);
 462
 463         if (!sigio_perm(p, fown, signum))
 464                 return;
 465
 466         switch (signum) {
 467                 siginfo_t si;
 468                 default:
 469                         /* Queue a rt signal with the appropriate fd as its
 470                            value.  We use SI_SIGIO as the source, not
 471                            SI_KERNEL, since kernel signals always get
 472                            delivered even if we can't queue.  Failure to
 473                            queue in this case _should_ be reported; we fall
 474                            back to SIGIO in that case. --sct */
 475                         si.si_signo = signum;
 476                         si.si_errno = 0;
 477                         si.si_code  = reason;
 478                         /* Make sure we are called with one of the POLL_*
 479                            reasons, otherwise we could leak kernel stack into
 480                            userspace.  */
 481                         BUG_ON((reason & __SI_MASK) != __SI_POLL);
 482                         if (reason - POLL_IN >= NSIGPOLL)
 483                                 si.si_band  = ~0L;
 484                         else
 485                                 si.si_band = band_table[reason - POLL_IN];
 486                         si.si_fd    = fd;
 487                         if (!do_send_sig_info(signum, &si, p, group))
 488                                 break;
 489                 /* fall-through: fall back on the old plain SIGIO signal */
 490                 case 0:
 491                         do_send_sig_info(SIGIO, SEND_SIG_PRIV, p, group);
 492         }
 493 }
 494
 495 void send_sigio(struct fown_struct *fown, int fd, int band)
 496 {
 497         struct task_struct *p;
 498         enum pid_type type;
 499         struct pid *pid;
 500         int group = 1;
 501
 502         read_lock(&fown->lock);
 503
 504         type = fown->pid_type;
 505         if (type == PIDTYPE_MAX) {
 506                 group = 0;
 507                 type = PIDTYPE_PID;
 508         }
 509
 510         pid = fown->pid;
 511         if (!pid)
 512                 goto out_unlock_fown;
 513
 514         read_lock(&tasklist_lock);
 515         do_each_pid_task(pid, type, p) {
 516                 send_sigio_to_task(p, fown, fd, band, group);
 517         } while_each_pid_task(pid, type, p);
 518         read_unlock(&tasklist_lock);
 519  out_unlock_fown:
 520         read_unlock(&fown->lock);
 521 }
 522
 523 static void send_sigurg_to_task(struct task_struct *p,
 524                                 struct fown_struct *fown, int group)
 525 {
 526         if (sigio_perm(p, fown, SIGURG))
 527                 do_send_sig_info(SIGURG, SEND_SIG_PRIV, p, group);
 528 }
 529
 530 int send_sigurg(struct fown_struct *fown)
 531 {
 532         struct task_struct *p;
 533         enum pid_type type;
 534         struct pid *pid;
 535         int group = 1;
 536         int ret = 0;
 537
 538         read_lock(&fown->lock);
 539
 540         type = fown->pid_type;
 541         if (type == PIDTYPE_MAX) {
 542                 group = 0;
 543                 type = PIDTYPE_PID;
 544         }
 545
 546         pid = fown->pid;
 547         if (!pid)
 548                 goto out_unlock_fown;
 549
 550         ret = 1;
 551
 552         read_lock(&tasklist_lock);
 553         do_each_pid_task(pid, type, p) {
 554                 send_sigurg_to_task(p, fown, group);
 555         } while_each_pid_task(pid, type, p);
 556         read_unlock(&tasklist_lock);
 557  out_unlock_fown:
 558         read_unlock(&fown->lock);
 559         return ret;
 560 }
 561
 562 static DEFINE_SPINLOCK(fasync_lock);
 563 static struct kmem_cache *fasync_cache __read_mostly;
 564
 565 static void fasync_free_rcu(struct rcu_head *head)
 566 {
 567         kmem_cache_free(fasync_cache,
 568                         container_of(head, struct fasync_struct, fa_rcu));
 569 }
 570
 571 /*
 572  * Remove a fasync entry. If successfully removed, return
 573  * positive and clear the FASYNC flag. If no entry exists,
 574  * do nothing and return 0.
 575  *
 576  * NOTE! It is very important that the FASYNC flag always
 577  * match the state "is the filp on a fasync list".
 578  *
 579  */
 580 int fasync_remove_entry(struct file *filp, struct fasync_struct **fapp)
 581 {
 582         struct fasync_struct *fa, **fp;
 583         int result = 0;
 584
 585         spin_lock(&filp->f_lock);
 586         spin_lock(&fasync_lock);
 587         for (fp = fapp; (fa = *fp) != NULL; fp = &fa->fa_next) {
 588                 if (fa->fa_file != filp)
 589                         continue;
 590
 591                 spin_lock_irq(&fa->fa_lock);
 592                 fa->fa_file = NULL;
 593                 spin_unlock_irq(&fa->fa_lock);
 594
 595                 *fp = fa->fa_next;
 596                 call_rcu(&fa->fa_rcu, fasync_free_rcu);
 597                 filp->f_flags &= ~FASYNC;
 598                 result = 1;
 599                 break;
 600         }
 601         spin_unlock(&fasync_lock);
 602         spin_unlock(&filp->f_lock);
 603         return result;
 604 }
 605
 606 struct fasync_struct *fasync_alloc(void)
 607 {
 608         return kmem_cache_alloc(fasync_cache, GFP_KERNEL);
 609 }
 610
 611 /*
 612  * NOTE! This can be used only for unused fasync entries:
 613  * entries that actually got inserted on the fasync list
 614  * need to be released by rcu - see fasync_remove_entry.
 615  */
 616 void fasync_free(struct fasync_struct *new)
 617 {
 618         kmem_cache_free(fasync_cache, new);
 619 }
 620
 621 /*
 622  * Insert a new entry into the fasync list.  Return the pointer to the
 623  * old one if we didn't use the new one.
 624  *
 625  * NOTE! It is very important that the FASYNC flag always
 626  * match the state "is the filp on a fasync list".
 627  */
 628 struct fasync_struct *fasync_insert_entry(int fd, struct file *filp, struct fasync_struct **fapp, struct fasync_struct *new)
 629 {
 630         struct fasync_struct *fa, **fp;
 631
 632         spin_lock(&filp->f_lock);
 633         spin_lock(&fasync_lock);
 634         for (fp = fapp; (fa = *fp) != NULL; fp = &fa->fa_next) {
 635                 if (fa->fa_file != filp)
 636                         continue;
 637
 638                 spin_lock_irq(&fa->fa_lock);
 639                 fa->fa_fd = fd;
 640                 spin_unlock_irq(&fa->fa_lock);
 641                 goto out;
 642         }
 643
 644         spin_lock_init(&new->fa_lock);
 645         new->magic = FASYNC_MAGIC;
 646         new->fa_file = filp;
 647         new->fa_fd = fd;
 648         new->fa_next = *fapp;
 649         rcu_assign_pointer(*fapp, new);
 650         filp->f_flags |= FASYNC;
 651
 652 out:
 653         spin_unlock(&fasync_lock);
 654         spin_unlock(&filp->f_lock);
 655         return fa;
 656 }
 657
 658 /*
 659  * Add a fasync entry. Return negative on error, positive if
 660  * added, and zero if did nothing but change an existing one.
 661  */
 662 static int fasync_add_entry(int fd, struct file *filp, struct fasync_struct **fapp)
 663 {
 664         struct fasync_struct *new;
 665
 666         new = fasync_alloc();
 667         if (!new)
 668                 return -ENOMEM;
 669
 670         /*
 671          * fasync_insert_entry() returns the old (update) entry if
 672          * it existed.
 673          *
 674          * So free the (unused) new entry and return 0 to let the
 675          * caller know that we didn't add any new fasync entries.
 676          */
 677         if (fasync_insert_entry(fd, filp, fapp, new)) {
 678                 fasync_free(new);
 679                 return 0;
 680         }
 681
 682         return 1;
 683 }
 684
 685 /*
 686  * fasync_helper() is used by almost all character device drivers
 687  * to set up the fasync queue, and for regular files by the file
 688  * lease code. It returns negative on error, 0 if it did no changes
 689  * and positive if it added/deleted the entry.
 690  */
 691 int fasync_helper(int fd, struct file * filp, int on, struct fasync_struct **fapp)
 692 {
 693         if (!on)
 694                 return fasync_remove_entry(filp, fapp);
 695         return fasync_add_entry(fd, filp, fapp);
 696 }
 697
 698 EXPORT_SYMBOL(fasync_helper);
 699
 700 /*
 701  * rcu_read_lock() is held
 702  */
 703 static void kill_fasync_rcu(struct fasync_struct *fa, int sig, int band)
 704 {
 705         while (fa) {
 706                 struct fown_struct *fown;
 707                 unsigned long flags;
 708
 709                 if (fa->magic != FASYNC_MAGIC) {
 710                         printk(KERN_ERR "kill_fasync: bad magic number in "
 711                                "fasync_struct!\n");
 712                         return;
 713                 }
 714                 spin_lock_irqsave(&fa->fa_lock, flags);
 715                 if (fa->fa_file) {
 716                         fown = &fa->fa_file->f_owner;
 717                         /* Don't send SIGURG to processes which have not set a
 718                            queued signum: SIGURG has its own default signalling
 719                            mechanism. */
 720                         if (!(sig == SIGURG && fown->signum == 0))
 721                                 send_sigio(fown, fa->fa_fd, band);
 722                 }
 723                 spin_unlock_irqrestore(&fa->fa_lock, flags);
 724                 fa = rcu_dereference(fa->fa_next);
 725         }
 726 }
 727
 728 void kill_fasync(struct fasync_struct **fp, int sig, int band)
 729 {
 730         /* First a quick test without locking: usually
 731          * the list is empty.
 732          */
 733         if (*fp) {
 734                 rcu_read_lock();
 735                 kill_fasync_rcu(rcu_dereference(*fp), sig, band);
 736                 rcu_read_unlock();
 737         }
 738 }
 739 EXPORT_SYMBOL(kill_fasync);
 740
 741 static int __init fcntl_init(void)
 742 {
 743         /*
 744          * Please add new bits here to ensure allocation uniqueness.
 745          * Exceptions: O_NONBLOCK is a two bit define on parisc; O_NDELAY
 746          * is defined as O_NONBLOCK on some platforms and not on others.
 747          */
 748         BUILD_BUG_ON(21 - 1 /* for O_RDONLY being 0 */ !=
 749                 HWEIGHT32(
 750                         (VALID_OPEN_FLAGS & ~(O_NONBLOCK | O_NDELAY)) |
 751                         __FMODE_EXEC | __FMODE_NONOTIFY));
 752
 753         fasync_cache = kmem_cache_create("fasync_cache",
 754                 sizeof(struct fasync_struct), 0, SLAB_PANIC, NULL);
 755         return 0;
 756 }
 757
 758 module_init(fcntl_init)