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 int __f_setown(struct file *filp, struct pid *pid, enum pid_type type,
 102                 int force)
 103 {
 104         int err;
 105
 106         err = security_file_set_fowner(filp);
 107         if (err)
 108                 return err;
 109
 110         f_modown(filp, pid, type, force);
 111         return 0;
 112 }
 113 EXPORT_SYMBOL(__f_setown);
 114
 115 int f_setown(struct file *filp, unsigned long arg, int force)
 116 {
 117         enum pid_type type;
 118         struct pid *pid;
 119         int who = arg;
 120         int result;
 121         type = PIDTYPE_PID;
 122         if (who < 0) {
 123                 type = PIDTYPE_PGID;
 124                 who = -who;
 125         }
 126         rcu_read_lock();
 127         pid = find_vpid(who);
 128         result = __f_setown(filp, pid, type, force);
 129         rcu_read_unlock();
 130         return result;
 131 }
 132 EXPORT_SYMBOL(f_setown);
 133
 134 void f_delown(struct file *filp)
 135 {
 136         f_modown(filp, NULL, PIDTYPE_PID, 1);
 137 }
 138
 139 pid_t f_getown(struct file *filp)
 140 {
 141         pid_t pid;
 142         read_lock(&filp->f_owner.lock);
 143         pid = pid_vnr(filp->f_owner.pid);
 144         if (filp->f_owner.pid_type == PIDTYPE_PGID)
 145                 pid = -pid;
 146         read_unlock(&filp->f_owner.lock);
 147         return pid;
 148 }
 149
 150 static int f_setown_ex(struct file *filp, unsigned long arg)
 151 {
 152         struct f_owner_ex __user *owner_p = (void __user *)arg;
 153         struct f_owner_ex owner;
 154         struct pid *pid;
 155         int type;
 156         int ret;
 157
 158         ret = copy_from_user(&owner, owner_p, sizeof(owner));
 159         if (ret)
 160                 return -EFAULT;
 161
 162         switch (owner.type) {
 163         case F_OWNER_TID:
 164                 type = PIDTYPE_MAX;
 165                 break;
 166
 167         case F_OWNER_PID:
 168                 type = PIDTYPE_PID;
 169                 break;
 170
 171         case F_OWNER_PGRP:
 172                 type = PIDTYPE_PGID;
 173                 break;
 174
 175         default:
 176                 return -EINVAL;
 177         }
 178
 179         rcu_read_lock();
 180         pid = find_vpid(owner.pid);
 181         if (owner.pid && !pid)
 182                 ret = -ESRCH;
 183         else
 184                 ret = __f_setown(filp, pid, type, 1);
 185         rcu_read_unlock();
 186
 187         return ret;
 188 }
 189
 190 static int f_getown_ex(struct file *filp, unsigned long arg)
 191 {
 192         struct f_owner_ex __user *owner_p = (void __user *)arg;
 193         struct f_owner_ex owner;
 194         int ret = 0;
 195
 196         read_lock(&filp->f_owner.lock);
 197         owner.pid = pid_vnr(filp->f_owner.pid);
 198         switch (filp->f_owner.pid_type) {
 199         case PIDTYPE_MAX:
 200                 owner.type = F_OWNER_TID;
 201                 break;
 202
 203         case PIDTYPE_PID:
 204                 owner.type = F_OWNER_PID;
 205                 break;
 206
 207         case PIDTYPE_PGID:
 208                 owner.type = F_OWNER_PGRP;
 209                 break;
 210
 211         default:
 212                 WARN_ON(1);
 213                 ret = -EINVAL;
 214                 break;
 215         }
 216         read_unlock(&filp->f_owner.lock);
 217
 218         if (!ret) {
 219                 ret = copy_to_user(owner_p, &owner, sizeof(owner));
 220                 if (ret)
 221                         ret = -EFAULT;
 222         }
 223         return ret;
 224 }
 225
 226 #ifdef CONFIG_CHECKPOINT_RESTORE
 227 static int f_getowner_uids(struct file *filp, unsigned long arg)
 228 {
 229         struct user_namespace *user_ns = current_user_ns();
 230         uid_t __user *dst = (void __user *)arg;
 231         uid_t src[2];
 232         int err;
 233
 234         read_lock(&filp->f_owner.lock);
 235         src[0] = from_kuid(user_ns, filp->f_owner.uid);
 236         src[1] = from_kuid(user_ns, filp->f_owner.euid);
 237         read_unlock(&filp->f_owner.lock);
 238
 239         err  = put_user(src[0], &dst[0]);
 240         err |= put_user(src[1], &dst[1]);
 241
 242         return err;
 243 }
 244 #else
 245 static int f_getowner_uids(struct file *filp, unsigned long arg)
 246 {
 247         return -EINVAL;
 248 }
 249 #endif
 250
 251 static long do_fcntl(int fd, unsigned int cmd, unsigned long arg,
 252                 struct file *filp)
 253 {
 254         long err = -EINVAL;
 255
 256         switch (cmd) {
 257         case F_DUPFD:
 258                 err = f_dupfd(arg, filp, 0);
 259                 break;
 260         case F_DUPFD_CLOEXEC:
 261                 err = f_dupfd(arg, filp, O_CLOEXEC);
 262                 break;
 263         case F_GETFD:
 264                 err = get_close_on_exec(fd) ? FD_CLOEXEC : 0;
 265                 break;
 266         case F_SETFD:
 267                 err = 0;
 268                 set_close_on_exec(fd, arg & FD_CLOEXEC);
 269                 break;
 270         case F_GETFL:
 271                 err = filp->f_flags;
 272                 break;
 273         case F_SETFL:
 274                 err = setfl(fd, filp, arg);
 275                 break;
 276 #if BITS_PER_LONG != 32
 277         /* 32-bit arches must use fcntl64() */
 278         case F_OFD_GETLK:
 279 #endif
 280         case F_GETLK:
 281                 err = fcntl_getlk(filp, cmd, (struct flock __user *) arg);
 282                 break;
 283 #if BITS_PER_LONG != 32
 284         /* 32-bit arches must use fcntl64() */
 285         case F_OFD_SETLK:
 286         case F_OFD_SETLKW:
 287 #endif
 288                 /* Fallthrough */
 289         case F_SETLK:
 290         case F_SETLKW:
 291                 err = fcntl_setlk(fd, filp, cmd, (struct flock __user *) arg);
 292                 break;
 293         case F_GETOWN:
 294                 /*
 295                  * XXX If f_owner is a process group, the
 296                  * negative return value will get converted
 297                  * into an error.  Oops.  If we keep the
 298                  * current syscall conventions, the only way
 299                  * to fix this will be in libc.
 300                  */
 301                 err = f_getown(filp);
 302                 force_successful_syscall_return();
 303                 break;
 304         case F_SETOWN:
 305                 err = f_setown(filp, arg, 1);
 306                 break;
 307         case F_GETOWN_EX:
 308                 err = f_getown_ex(filp, arg);
 309                 break;
 310         case F_SETOWN_EX:
 311                 err = f_setown_ex(filp, arg);
 312                 break;
 313         case F_GETOWNER_UIDS:
 314                 err = f_getowner_uids(filp, arg);
 315                 break;
 316         case F_GETSIG:
 317                 err = filp->f_owner.signum;
 318                 break;
 319         case F_SETSIG:
 320                 /* arg == 0 restores default behaviour. */
 321                 if (!valid_signal(arg)) {
 322                         break;
 323                 }
 324                 err = 0;
 325                 filp->f_owner.signum = arg;
 326                 break;
 327         case F_GETLEASE:
 328                 err = fcntl_getlease(filp);
 329                 break;
 330         case F_SETLEASE:
 331                 err = fcntl_setlease(fd, filp, arg);
 332                 break;
 333         case F_NOTIFY:
 334                 err = fcntl_dirnotify(fd, filp, arg);
 335                 break;
 336         case F_SETPIPE_SZ:
 337         case F_GETPIPE_SZ:
 338                 err = pipe_fcntl(filp, cmd, arg);
 339                 break;
 340         case F_ADD_SEALS:
 341         case F_GET_SEALS:
 342                 err = shmem_fcntl(filp, cmd, arg);
 343                 break;
 344         default:
 345                 break;
 346         }
 347         return err;
 348 }
 349
 350 static int check_fcntl_cmd(unsigned cmd)
 351 {
 352         switch (cmd) {
 353         case F_DUPFD:
 354         case F_DUPFD_CLOEXEC:
 355         case F_GETFD:
 356         case F_SETFD:
 357         case F_GETFL:
 358                 return 1;
 359         }
 360         return 0;
 361 }
 362
 363 SYSCALL_DEFINE3(fcntl, unsigned int, fd, unsigned int, cmd, unsigned long, arg)
 364 {
 365         struct fd f = fdget_raw(fd);
 366         long err = -EBADF;
 367
 368         if (!f.file)
 369                 goto out;
 370
 371         if (unlikely(f.file->f_mode & FMODE_PATH)) {
 372                 if (!check_fcntl_cmd(cmd))
 373                         goto out1;
 374         }
 375
 376         err = security_file_fcntl(f.file, cmd, arg);
 377         if (!err)
 378                 err = do_fcntl(fd, cmd, arg, f.file);
 379
 380 out1:
 381         fdput(f);
 382 out:
 383         return err;
 384 }
 385
 386 #if BITS_PER_LONG == 32
 387 SYSCALL_DEFINE3(fcntl64, unsigned int, fd, unsigned int, cmd,
 388                 unsigned long, arg)
 389 {
 390         struct fd f = fdget_raw(fd);
 391         long err = -EBADF;
 392
 393         if (!f.file)
 394                 goto out;
 395
 396         if (unlikely(f.file->f_mode & FMODE_PATH)) {
 397                 if (!check_fcntl_cmd(cmd))
 398                         goto out1;
 399         }
 400
 401         err = security_file_fcntl(f.file, cmd, arg);
 402         if (err)
 403                 goto out1;
 404
 405         switch (cmd) {
 406         case F_GETLK64:
 407         case F_OFD_GETLK:
 408                 err = fcntl_getlk64(f.file, cmd, (struct flock64 __user *) arg);
 409                 break;
 410         case F_SETLK64:
 411         case F_SETLKW64:
 412         case F_OFD_SETLK:
 413         case F_OFD_SETLKW:
 414                 err = fcntl_setlk64(fd, f.file, cmd,
 415                                 (struct flock64 __user *) arg);
 416                 break;
 417         default:
 418                 err = do_fcntl(fd, cmd, arg, f.file);
 419                 break;
 420         }
 421 out1:
 422         fdput(f);
 423 out:
 424         return err;
 425 }
 426 #endif
 427
 428 /* Table to convert sigio signal codes into poll band bitmaps */
 429
 430 static const long band_table[NSIGPOLL] = {
 431         POLLIN | POLLRDNORM,                    /* POLL_IN */
 432         POLLOUT | POLLWRNORM | POLLWRBAND,      /* POLL_OUT */
 433         POLLIN | POLLRDNORM | POLLMSG,          /* POLL_MSG */
 434         POLLERR,                                /* POLL_ERR */
 435         POLLPRI | POLLRDBAND,                   /* POLL_PRI */
 436         POLLHUP | POLLERR                       /* POLL_HUP */
 437 };
 438
 439 static inline int sigio_perm(struct task_struct *p,
 440                              struct fown_struct *fown, int sig)
 441 {
 442         const struct cred *cred;
 443         int ret;
 444
 445         rcu_read_lock();
 446         cred = __task_cred(p);
 447         ret = ((uid_eq(fown->euid, GLOBAL_ROOT_UID) ||
 448                 uid_eq(fown->euid, cred->suid) || uid_eq(fown->euid, cred->uid) ||
 449                 uid_eq(fown->uid,  cred->suid) || uid_eq(fown->uid,  cred->uid)) &&
 450                !security_file_send_sigiotask(p, fown, sig));
 451         rcu_read_unlock();
 452         return ret;
 453 }
 454
 455 static void send_sigio_to_task(struct task_struct *p,
 456                                struct fown_struct *fown,
 457                                int fd, int reason, int group)
 458 {
 459         /*
 460          * F_SETSIG can change ->signum lockless in parallel, make
 461          * sure we read it once and use the same value throughout.
 462          */
 463         int signum = ACCESS_ONCE(fown->signum);
 464
 465         if (!sigio_perm(p, fown, signum))
 466                 return;
 467
 468         switch (signum) {
 469                 siginfo_t si;
 470                 default:
 471                         /* Queue a rt signal with the appropriate fd as its
 472                            value.  We use SI_SIGIO as the source, not
 473                            SI_KERNEL, since kernel signals always get
 474                            delivered even if we can't queue.  Failure to
 475                            queue in this case _should_ be reported; we fall
 476                            back to SIGIO in that case. --sct */
 477                         si.si_signo = signum;
 478                         si.si_errno = 0;
 479                         si.si_code  = reason;
 480                         /* Make sure we are called with one of the POLL_*
 481                            reasons, otherwise we could leak kernel stack into
 482                            userspace.  */
 483                         BUG_ON((reason & __SI_MASK) != __SI_POLL);
 484                         if (reason - POLL_IN >= NSIGPOLL)
 485                                 si.si_band  = ~0L;
 486                         else
 487                                 si.si_band = band_table[reason - POLL_IN];
 488                         si.si_fd    = fd;
 489                         if (!do_send_sig_info(signum, &si, p, group))
 490                                 break;
 491                 /* fall-through: fall back on the old plain SIGIO signal */
 492                 case 0:
 493                         do_send_sig_info(SIGIO, SEND_SIG_PRIV, p, group);
 494         }
 495 }
 496
 497 void send_sigio(struct fown_struct *fown, int fd, int band)
 498 {
 499         struct task_struct *p;
 500         enum pid_type type;
 501         struct pid *pid;
 502         int group = 1;
 503
 504         read_lock(&fown->lock);
 505
 506         type = fown->pid_type;
 507         if (type == PIDTYPE_MAX) {
 508                 group = 0;
 509                 type = PIDTYPE_PID;
 510         }
 511
 512         pid = fown->pid;
 513         if (!pid)
 514                 goto out_unlock_fown;
 515
 516         read_lock(&tasklist_lock);
 517         do_each_pid_task(pid, type, p) {
 518                 send_sigio_to_task(p, fown, fd, band, group);
 519         } while_each_pid_task(pid, type, p);
 520         read_unlock(&tasklist_lock);
 521  out_unlock_fown:
 522         read_unlock(&fown->lock);
 523 }
 524
 525 static void send_sigurg_to_task(struct task_struct *p,
 526                                 struct fown_struct *fown, int group)
 527 {
 528         if (sigio_perm(p, fown, SIGURG))
 529                 do_send_sig_info(SIGURG, SEND_SIG_PRIV, p, group);
 530 }
 531
 532 int send_sigurg(struct fown_struct *fown)
 533 {
 534         struct task_struct *p;
 535         enum pid_type type;
 536         struct pid *pid;
 537         int group = 1;
 538         int ret = 0;
 539
 540         read_lock(&fown->lock);
 541
 542         type = fown->pid_type;
 543         if (type == PIDTYPE_MAX) {
 544                 group = 0;
 545                 type = PIDTYPE_PID;
 546         }
 547
 548         pid = fown->pid;
 549         if (!pid)
 550                 goto out_unlock_fown;
 551
 552         ret = 1;
 553
 554         read_lock(&tasklist_lock);
 555         do_each_pid_task(pid, type, p) {
 556                 send_sigurg_to_task(p, fown, group);
 557         } while_each_pid_task(pid, type, p);
 558         read_unlock(&tasklist_lock);
 559  out_unlock_fown:
 560         read_unlock(&fown->lock);
 561         return ret;
 562 }
 563
 564 static DEFINE_SPINLOCK(fasync_lock);
 565 static struct kmem_cache *fasync_cache __read_mostly;
 566
 567 static void fasync_free_rcu(struct rcu_head *head)
 568 {
 569         kmem_cache_free(fasync_cache,
 570                         container_of(head, struct fasync_struct, fa_rcu));
 571 }
 572
 573 /*
 574  * Remove a fasync entry. If successfully removed, return
 575  * positive and clear the FASYNC flag. If no entry exists,
 576  * do nothing and return 0.
 577  *
 578  * NOTE! It is very important that the FASYNC flag always
 579  * match the state "is the filp on a fasync list".
 580  *
 581  */
 582 int fasync_remove_entry(struct file *filp, struct fasync_struct **fapp)
 583 {
 584         struct fasync_struct *fa, **fp;
 585         int result = 0;
 586
 587         spin_lock(&filp->f_lock);
 588         spin_lock(&fasync_lock);
 589         for (fp = fapp; (fa = *fp) != NULL; fp = &fa->fa_next) {
 590                 if (fa->fa_file != filp)
 591                         continue;
 592
 593                 spin_lock_irq(&fa->fa_lock);
 594                 fa->fa_file = NULL;
 595                 spin_unlock_irq(&fa->fa_lock);
 596
 597                 *fp = fa->fa_next;
 598                 call_rcu(&fa->fa_rcu, fasync_free_rcu);
 599                 filp->f_flags &= ~FASYNC;
 600                 result = 1;
 601                 break;
 602         }
 603         spin_unlock(&fasync_lock);
 604         spin_unlock(&filp->f_lock);
 605         return result;
 606 }
 607
 608 struct fasync_struct *fasync_alloc(void)
 609 {
 610         return kmem_cache_alloc(fasync_cache, GFP_KERNEL);
 611 }
 612
 613 /*
 614  * NOTE! This can be used only for unused fasync entries:
 615  * entries that actually got inserted on the fasync list
 616  * need to be released by rcu - see fasync_remove_entry.
 617  */
 618 void fasync_free(struct fasync_struct *new)
 619 {
 620         kmem_cache_free(fasync_cache, new);
 621 }
 622
 623 /*
 624  * Insert a new entry into the fasync list.  Return the pointer to the
 625  * old one if we didn't use the new one.
 626  *
 627  * NOTE! It is very important that the FASYNC flag always
 628  * match the state "is the filp on a fasync list".
 629  */
 630 struct fasync_struct *fasync_insert_entry(int fd, struct file *filp, struct fasync_struct **fapp, struct fasync_struct *new)
 631 {
 632         struct fasync_struct *fa, **fp;
 633
 634         spin_lock(&filp->f_lock);
 635         spin_lock(&fasync_lock);
 636         for (fp = fapp; (fa = *fp) != NULL; fp = &fa->fa_next) {
 637                 if (fa->fa_file != filp)
 638                         continue;
 639
 640                 spin_lock_irq(&fa->fa_lock);
 641                 fa->fa_fd = fd;
 642                 spin_unlock_irq(&fa->fa_lock);
 643                 goto out;
 644         }
 645
 646         spin_lock_init(&new->fa_lock);
 647         new->magic = FASYNC_MAGIC;
 648         new->fa_file = filp;
 649         new->fa_fd = fd;
 650         new->fa_next = *fapp;
 651         rcu_assign_pointer(*fapp, new);
 652         filp->f_flags |= FASYNC;
 653
 654 out:
 655         spin_unlock(&fasync_lock);
 656         spin_unlock(&filp->f_lock);
 657         return fa;
 658 }
 659
 660 /*
 661  * Add a fasync entry. Return negative on error, positive if
 662  * added, and zero if did nothing but change an existing one.
 663  */
 664 static int fasync_add_entry(int fd, struct file *filp, struct fasync_struct **fapp)
 665 {
 666         struct fasync_struct *new;
 667
 668         new = fasync_alloc();
 669         if (!new)
 670                 return -ENOMEM;
 671
 672         /*
 673          * fasync_insert_entry() returns the old (update) entry if
 674          * it existed.
 675          *
 676          * So free the (unused) new entry and return 0 to let the
 677          * caller know that we didn't add any new fasync entries.
 678          */
 679         if (fasync_insert_entry(fd, filp, fapp, new)) {
 680                 fasync_free(new);
 681                 return 0;
 682         }
 683
 684         return 1;
 685 }
 686
 687 /*
 688  * fasync_helper() is used by almost all character device drivers
 689  * to set up the fasync queue, and for regular files by the file
 690  * lease code. It returns negative on error, 0 if it did no changes
 691  * and positive if it added/deleted the entry.
 692  */
 693 int fasync_helper(int fd, struct file * filp, int on, struct fasync_struct **fapp)
 694 {
 695         if (!on)
 696                 return fasync_remove_entry(filp, fapp);
 697         return fasync_add_entry(fd, filp, fapp);
 698 }
 699
 700 EXPORT_SYMBOL(fasync_helper);
 701
 702 /*
 703  * rcu_read_lock() is held
 704  */
 705 static void kill_fasync_rcu(struct fasync_struct *fa, int sig, int band)
 706 {
 707         while (fa) {
 708                 struct fown_struct *fown;
 709                 unsigned long flags;
 710
 711                 if (fa->magic != FASYNC_MAGIC) {
 712                         printk(KERN_ERR "kill_fasync: bad magic number in "
 713                                "fasync_struct!\n");
 714                         return;
 715                 }
 716                 spin_lock_irqsave(&fa->fa_lock, flags);
 717                 if (fa->fa_file) {
 718                         fown = &fa->fa_file->f_owner;
 719                         /* Don't send SIGURG to processes which have not set a
 720                            queued signum: SIGURG has its own default signalling
 721                            mechanism. */
 722                         if (!(sig == SIGURG && fown->signum == 0))
 723                                 send_sigio(fown, fa->fa_fd, band);
 724                 }
 725                 spin_unlock_irqrestore(&fa->fa_lock, flags);
 726                 fa = rcu_dereference(fa->fa_next);
 727         }
 728 }
 729
 730 void kill_fasync(struct fasync_struct **fp, int sig, int band)
 731 {
 732         /* First a quick test without locking: usually
 733          * the list is empty.
 734          */
 735         if (*fp) {
 736                 rcu_read_lock();
 737                 kill_fasync_rcu(rcu_dereference(*fp), sig, band);
 738                 rcu_read_unlock();
 739         }
 740 }
 741 EXPORT_SYMBOL(kill_fasync);
 742
 743 static int __init fcntl_init(void)
 744 {
 745         /*
 746          * Please add new bits here to ensure allocation uniqueness.
 747          * Exceptions: O_NONBLOCK is a two bit define on parisc; O_NDELAY
 748          * is defined as O_NONBLOCK on some platforms and not on others.
 749          */
 750         BUILD_BUG_ON(20 - 1 /* for O_RDONLY being 0 */ != HWEIGHT32(
 751                 O_RDONLY        | O_WRONLY      | O_RDWR        |
 752                 O_CREAT         | O_EXCL        | O_NOCTTY      |
 753                 O_TRUNC         | O_APPEND      | /* O_NONBLOCK | */
 754                 __O_SYNC        | O_DSYNC       | FASYNC        |
 755                 O_DIRECT        | O_LARGEFILE   | O_DIRECTORY   |
 756                 O_NOFOLLOW      | O_NOATIME     | O_CLOEXEC     |
 757                 __FMODE_EXEC    | O_PATH        | __O_TMPFILE
 758                 ));
 759
 760         fasync_cache = kmem_cache_create("fasync_cache",
 761                 sizeof(struct fasync_struct), 0, SLAB_PANIC, NULL);
 762         return 0;
 763 }
 764
 765 module_init(fcntl_init)