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