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
  25 #include <asm/poll.h>
  26 #include <asm/siginfo.h>
  27 #include <asm/uaccess.h>
  28
  29 #define SETFL_MASK (O_APPEND | O_NONBLOCK | O_NDELAY | O_DIRECT | O_NOATIME)
  30
  31 static int setfl(int fd, struct file * filp, unsigned long arg)
  32 {
  33         struct inode * inode = file_inode(filp);
  34         int error = 0;
  35
  36         /*
  37          * O_APPEND cannot be cleared if the file is marked as append-only
  38          * and the file is open for write.
  39          */
  40         if (((arg ^ filp->f_flags) & O_APPEND) && IS_APPEND(inode))
  41                 return -EPERM;
  42
  43         /* O_NOATIME can only be set by the owner or superuser */
  44         if ((arg & O_NOATIME) && !(filp->f_flags & O_NOATIME))
  45                 if (!inode_owner_or_capable(inode))
  46                         return -EPERM;
  47
  48         /* required for strict SunOS emulation */
  49         if (O_NONBLOCK != O_NDELAY)
  50                if (arg & O_NDELAY)
  51                    arg |= O_NONBLOCK;
  52
  53         if (arg & O_DIRECT) {
  54                 if (!filp->f_mapping || !filp->f_mapping->a_ops ||
  55                         !filp->f_mapping->a_ops->direct_IO)
  56                                 return -EINVAL;
  57         }
  58
  59         if (filp->f_op && filp->f_op->check_flags)
  60                 error = filp->f_op->check_flags(arg);
  61         if (error)
  62                 return error;
  63
  64         /*
  65          * ->fasync() is responsible for setting the FASYNC bit.
  66          */
  67         if (((arg ^ filp->f_flags) & FASYNC) && filp->f_op &&
  68                         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         case F_GETLK:
 277                 err = fcntl_getlk(filp, (struct flock __user *) arg);
 278                 break;
 279         case F_SETLK:
 280         case F_SETLKW:
 281                 err = fcntl_setlk(fd, filp, cmd, (struct flock __user *) arg);
 282                 break;
 283         case F_GETOWN:
 284                 /*
 285                  * XXX If f_owner is a process group, the
 286                  * negative return value will get converted
 287                  * into an error.  Oops.  If we keep the
 288                  * current syscall conventions, the only way
 289                  * to fix this will be in libc.
 290                  */
 291                 err = f_getown(filp);
 292                 force_successful_syscall_return();
 293                 break;
 294         case F_SETOWN:
 295                 err = f_setown(filp, arg, 1);
 296                 break;
 297         case F_GETOWN_EX:
 298                 err = f_getown_ex(filp, arg);
 299                 break;
 300         case F_SETOWN_EX:
 301                 err = f_setown_ex(filp, arg);
 302                 break;
 303         case F_GETOWNER_UIDS:
 304                 err = f_getowner_uids(filp, arg);
 305                 break;
 306         case F_GETSIG:
 307                 err = filp->f_owner.signum;
 308                 break;
 309         case F_SETSIG:
 310                 /* arg == 0 restores default behaviour. */
 311                 if (!valid_signal(arg)) {
 312                         break;
 313                 }
 314                 err = 0;
 315                 filp->f_owner.signum = arg;
 316                 break;
 317         case F_GETLEASE:
 318                 err = fcntl_getlease(filp);
 319                 break;
 320         case F_SETLEASE:
 321                 err = fcntl_setlease(fd, filp, arg);
 322                 break;
 323         case F_NOTIFY:
 324                 err = fcntl_dirnotify(fd, filp, arg);
 325                 break;
 326         case F_SETPIPE_SZ:
 327         case F_GETPIPE_SZ:
 328                 err = pipe_fcntl(filp, cmd, arg);
 329                 break;
 330         default:
 331                 break;
 332         }
 333         return err;
 334 }
 335
 336 static int check_fcntl_cmd(unsigned cmd)
 337 {
 338         switch (cmd) {
 339         case F_DUPFD:
 340         case F_DUPFD_CLOEXEC:
 341         case F_GETFD:
 342         case F_SETFD:
 343         case F_GETFL:
 344                 return 1;
 345         }
 346         return 0;
 347 }
 348
 349 SYSCALL_DEFINE3(fcntl, unsigned int, fd, unsigned int, cmd, unsigned long, arg)
 350 {
 351         struct fd f = fdget_raw(fd);
 352         long err = -EBADF;
 353
 354         if (!f.file)
 355                 goto out;
 356
 357         if (unlikely(f.file->f_mode & FMODE_PATH)) {
 358                 if (!check_fcntl_cmd(cmd))
 359                         goto out1;
 360         }
 361
 362         err = security_file_fcntl(f.file, cmd, arg);
 363         if (!err)
 364                 err = do_fcntl(fd, cmd, arg, f.file);
 365
 366 out1:
 367         fdput(f);
 368 out:
 369         return err;
 370 }
 371
 372 #if BITS_PER_LONG == 32
 373 SYSCALL_DEFINE3(fcntl64, unsigned int, fd, unsigned int, cmd,
 374                 unsigned long, arg)
 375 {
 376         struct fd f = fdget_raw(fd);
 377         long err = -EBADF;
 378
 379         if (!f.file)
 380                 goto out;
 381
 382         if (unlikely(f.file->f_mode & FMODE_PATH)) {
 383                 if (!check_fcntl_cmd(cmd))
 384                         goto out1;
 385         }
 386
 387         err = security_file_fcntl(f.file, cmd, arg);
 388         if (err)
 389                 goto out1;
 390
 391         switch (cmd) {
 392                 case F_GETLK64:
 393                         err = fcntl_getlk64(f.file, (struct flock64 __user *) arg);
 394                         break;
 395                 case F_SETLK64:
 396                 case F_SETLKW64:
 397                         err = fcntl_setlk64(fd, f.file, cmd,
 398                                         (struct flock64 __user *) arg);
 399                         break;
 400                 default:
 401                         err = do_fcntl(fd, cmd, arg, f.file);
 402                         break;
 403         }
 404 out1:
 405         fdput(f);
 406 out:
 407         return err;
 408 }
 409 #endif
 410
 411 /* Table to convert sigio signal codes into poll band bitmaps */
 412
 413 static const long band_table[NSIGPOLL] = {
 414         POLLIN | POLLRDNORM,                    /* POLL_IN */
 415         POLLOUT | POLLWRNORM | POLLWRBAND,      /* POLL_OUT */
 416         POLLIN | POLLRDNORM | POLLMSG,          /* POLL_MSG */
 417         POLLERR,                                /* POLL_ERR */
 418         POLLPRI | POLLRDBAND,                   /* POLL_PRI */
 419         POLLHUP | POLLERR                       /* POLL_HUP */
 420 };
 421
 422 static inline int sigio_perm(struct task_struct *p,
 423                              struct fown_struct *fown, int sig)
 424 {
 425         const struct cred *cred;
 426         int ret;
 427
 428         rcu_read_lock();
 429         cred = __task_cred(p);
 430         ret = ((uid_eq(fown->euid, GLOBAL_ROOT_UID) ||
 431                 uid_eq(fown->euid, cred->suid) || uid_eq(fown->euid, cred->uid) ||
 432                 uid_eq(fown->uid,  cred->suid) || uid_eq(fown->uid,  cred->uid)) &&
 433                !security_file_send_sigiotask(p, fown, sig));
 434         rcu_read_unlock();
 435         return ret;
 436 }
 437
 438 static void send_sigio_to_task(struct task_struct *p,
 439                                struct fown_struct *fown,
 440                                int fd, int reason, int group)
 441 {
 442         /*
 443          * F_SETSIG can change ->signum lockless in parallel, make
 444          * sure we read it once and use the same value throughout.
 445          */
 446         int signum = ACCESS_ONCE(fown->signum);
 447
 448         if (!sigio_perm(p, fown, signum))
 449                 return;
 450
 451         switch (signum) {
 452                 siginfo_t si;
 453                 default:
 454                         /* Queue a rt signal with the appropriate fd as its
 455                            value.  We use SI_SIGIO as the source, not
 456                            SI_KERNEL, since kernel signals always get
 457                            delivered even if we can't queue.  Failure to
 458                            queue in this case _should_ be reported; we fall
 459                            back to SIGIO in that case. --sct */
 460                         si.si_signo = signum;
 461                         si.si_errno = 0;
 462                         si.si_code  = reason;
 463                         /* Make sure we are called with one of the POLL_*
 464                            reasons, otherwise we could leak kernel stack into
 465                            userspace.  */
 466                         BUG_ON((reason & __SI_MASK) != __SI_POLL);
 467                         if (reason - POLL_IN >= NSIGPOLL)
 468                                 si.si_band  = ~0L;
 469                         else
 470                                 si.si_band = band_table[reason - POLL_IN];
 471                         si.si_fd    = fd;
 472                         if (!do_send_sig_info(signum, &si, p, group))
 473                                 break;
 474                 /* fall-through: fall back on the old plain SIGIO signal */
 475                 case 0:
 476                         do_send_sig_info(SIGIO, SEND_SIG_PRIV, p, group);
 477         }
 478 }
 479
 480 void send_sigio(struct fown_struct *fown, int fd, int band)
 481 {
 482         struct task_struct *p;
 483         enum pid_type type;
 484         struct pid *pid;
 485         int group = 1;
 486
 487         read_lock(&fown->lock);
 488
 489         type = fown->pid_type;
 490         if (type == PIDTYPE_MAX) {
 491                 group = 0;
 492                 type = PIDTYPE_PID;
 493         }
 494
 495         pid = fown->pid;
 496         if (!pid)
 497                 goto out_unlock_fown;
 498
 499         read_lock(&tasklist_lock);
 500         do_each_pid_task(pid, type, p) {
 501                 send_sigio_to_task(p, fown, fd, band, group);
 502         } while_each_pid_task(pid, type, p);
 503         read_unlock(&tasklist_lock);
 504  out_unlock_fown:
 505         read_unlock(&fown->lock);
 506 }
 507
 508 static void send_sigurg_to_task(struct task_struct *p,
 509                                 struct fown_struct *fown, int group)
 510 {
 511         if (sigio_perm(p, fown, SIGURG))
 512                 do_send_sig_info(SIGURG, SEND_SIG_PRIV, p, group);
 513 }
 514
 515 int send_sigurg(struct fown_struct *fown)
 516 {
 517         struct task_struct *p;
 518         enum pid_type type;
 519         struct pid *pid;
 520         int group = 1;
 521         int ret = 0;
 522
 523         read_lock(&fown->lock);
 524
 525         type = fown->pid_type;
 526         if (type == PIDTYPE_MAX) {
 527                 group = 0;
 528                 type = PIDTYPE_PID;
 529         }
 530
 531         pid = fown->pid;
 532         if (!pid)
 533                 goto out_unlock_fown;
 534
 535         ret = 1;
 536
 537         read_lock(&tasklist_lock);
 538         do_each_pid_task(pid, type, p) {
 539                 send_sigurg_to_task(p, fown, group);
 540         } while_each_pid_task(pid, type, p);
 541         read_unlock(&tasklist_lock);
 542  out_unlock_fown:
 543         read_unlock(&fown->lock);
 544         return ret;
 545 }
 546
 547 static DEFINE_SPINLOCK(fasync_lock);
 548 static struct kmem_cache *fasync_cache __read_mostly;
 549
 550 static void fasync_free_rcu(struct rcu_head *head)
 551 {
 552         kmem_cache_free(fasync_cache,
 553                         container_of(head, struct fasync_struct, fa_rcu));
 554 }
 555
 556 /*
 557  * Remove a fasync entry. If successfully removed, return
 558  * positive and clear the FASYNC flag. If no entry exists,
 559  * do nothing and return 0.
 560  *
 561  * NOTE! It is very important that the FASYNC flag always
 562  * match the state "is the filp on a fasync list".
 563  *
 564  */
 565 int fasync_remove_entry(struct file *filp, struct fasync_struct **fapp)
 566 {
 567         struct fasync_struct *fa, **fp;
 568         int result = 0;
 569
 570         spin_lock(&filp->f_lock);
 571         spin_lock(&fasync_lock);
 572         for (fp = fapp; (fa = *fp) != NULL; fp = &fa->fa_next) {
 573                 if (fa->fa_file != filp)
 574                         continue;
 575
 576                 spin_lock_irq(&fa->fa_lock);
 577                 fa->fa_file = NULL;
 578                 spin_unlock_irq(&fa->fa_lock);
 579
 580                 *fp = fa->fa_next;
 581                 call_rcu(&fa->fa_rcu, fasync_free_rcu);
 582                 filp->f_flags &= ~FASYNC;
 583                 result = 1;
 584                 break;
 585         }
 586         spin_unlock(&fasync_lock);
 587         spin_unlock(&filp->f_lock);
 588         return result;
 589 }
 590
 591 struct fasync_struct *fasync_alloc(void)
 592 {
 593         return kmem_cache_alloc(fasync_cache, GFP_KERNEL);
 594 }
 595
 596 /*
 597  * NOTE! This can be used only for unused fasync entries:
 598  * entries that actually got inserted on the fasync list
 599  * need to be released by rcu - see fasync_remove_entry.
 600  */
 601 void fasync_free(struct fasync_struct *new)
 602 {
 603         kmem_cache_free(fasync_cache, new);
 604 }
 605
 606 /*
 607  * Insert a new entry into the fasync list.  Return the pointer to the
 608  * old one if we didn't use the new one.
 609  *
 610  * NOTE! It is very important that the FASYNC flag always
 611  * match the state "is the filp on a fasync list".
 612  */
 613 struct fasync_struct *fasync_insert_entry(int fd, struct file *filp, struct fasync_struct **fapp, struct fasync_struct *new)
 614 {
 615         struct fasync_struct *fa, **fp;
 616
 617         spin_lock(&filp->f_lock);
 618         spin_lock(&fasync_lock);
 619         for (fp = fapp; (fa = *fp) != NULL; fp = &fa->fa_next) {
 620                 if (fa->fa_file != filp)
 621                         continue;
 622
 623                 spin_lock_irq(&fa->fa_lock);
 624                 fa->fa_fd = fd;
 625                 spin_unlock_irq(&fa->fa_lock);
 626                 goto out;
 627         }
 628
 629         spin_lock_init(&new->fa_lock);
 630         new->magic = FASYNC_MAGIC;
 631         new->fa_file = filp;
 632         new->fa_fd = fd;
 633         new->fa_next = *fapp;
 634         rcu_assign_pointer(*fapp, new);
 635         filp->f_flags |= FASYNC;
 636
 637 out:
 638         spin_unlock(&fasync_lock);
 639         spin_unlock(&filp->f_lock);
 640         return fa;
 641 }
 642
 643 /*
 644  * Add a fasync entry. Return negative on error, positive if
 645  * added, and zero if did nothing but change an existing one.
 646  */
 647 static int fasync_add_entry(int fd, struct file *filp, struct fasync_struct **fapp)
 648 {
 649         struct fasync_struct *new;
 650
 651         new = fasync_alloc();
 652         if (!new)
 653                 return -ENOMEM;
 654
 655         /*
 656          * fasync_insert_entry() returns the old (update) entry if
 657          * it existed.
 658          *
 659          * So free the (unused) new entry and return 0 to let the
 660          * caller know that we didn't add any new fasync entries.
 661          */
 662         if (fasync_insert_entry(fd, filp, fapp, new)) {
 663                 fasync_free(new);
 664                 return 0;
 665         }
 666
 667         return 1;
 668 }
 669
 670 /*
 671  * fasync_helper() is used by almost all character device drivers
 672  * to set up the fasync queue, and for regular files by the file
 673  * lease code. It returns negative on error, 0 if it did no changes
 674  * and positive if it added/deleted the entry.
 675  */
 676 int fasync_helper(int fd, struct file * filp, int on, struct fasync_struct **fapp)
 677 {
 678         if (!on)
 679                 return fasync_remove_entry(filp, fapp);
 680         return fasync_add_entry(fd, filp, fapp);
 681 }
 682
 683 EXPORT_SYMBOL(fasync_helper);
 684
 685 /*
 686  * rcu_read_lock() is held
 687  */
 688 static void kill_fasync_rcu(struct fasync_struct *fa, int sig, int band)
 689 {
 690         while (fa) {
 691                 struct fown_struct *fown;
 692                 unsigned long flags;
 693
 694                 if (fa->magic != FASYNC_MAGIC) {
 695                         printk(KERN_ERR "kill_fasync: bad magic number in "
 696                                "fasync_struct!\n");
 697                         return;
 698                 }
 699                 spin_lock_irqsave(&fa->fa_lock, flags);
 700                 if (fa->fa_file) {
 701                         fown = &fa->fa_file->f_owner;
 702                         /* Don't send SIGURG to processes which have not set a
 703                            queued signum: SIGURG has its own default signalling
 704                            mechanism. */
 705                         if (!(sig == SIGURG && fown->signum == 0))
 706                                 send_sigio(fown, fa->fa_fd, band);
 707                 }
 708                 spin_unlock_irqrestore(&fa->fa_lock, flags);
 709                 fa = rcu_dereference(fa->fa_next);
 710         }
 711 }
 712
 713 void kill_fasync(struct fasync_struct **fp, int sig, int band)
 714 {
 715         /* First a quick test without locking: usually
 716          * the list is empty.
 717          */
 718         if (*fp) {
 719                 rcu_read_lock();
 720                 kill_fasync_rcu(rcu_dereference(*fp), sig, band);
 721                 rcu_read_unlock();
 722         }
 723 }
 724 EXPORT_SYMBOL(kill_fasync);
 725
 726 static int __init fcntl_init(void)
 727 {
 728         /*
 729          * Please add new bits here to ensure allocation uniqueness.
 730          * Exceptions: O_NONBLOCK is a two bit define on parisc; O_NDELAY
 731          * is defined as O_NONBLOCK on some platforms and not on others.
 732          */
 733         BUILD_BUG_ON(19 - 1 /* for O_RDONLY being 0 */ != HWEIGHT32(
 734                 O_RDONLY        | O_WRONLY      | O_RDWR        |
 735                 O_CREAT         | O_EXCL        | O_NOCTTY      |
 736                 O_TRUNC         | O_APPEND      | /* O_NONBLOCK | */
 737                 __O_SYNC        | O_DSYNC       | FASYNC        |
 738                 O_DIRECT        | O_LARGEFILE   | O_DIRECTORY   |
 739                 O_NOFOLLOW      | O_NOATIME     | O_CLOEXEC     |
 740                 __FMODE_EXEC    | O_PATH
 741                 ));
 742
 743         fasync_cache = kmem_cache_create("fasync_cache",
 744                 sizeof(struct fasync_struct), 0, SLAB_PANIC, NULL);
 745         return 0;
 746 }
 747
 748 module_init(fcntl_init)