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