Version:  2.0.40 2.2.26 2.4.37 3.13 3.14 3.15 3.16 3.17 3.18 3.19 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 4.10

Linux/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 <linux/uaccess.h>
 29 
 30 #define SETFL_MASK (O_APPEND | O_NONBLOCK | O_NDELAY | O_DIRECT | O_NOATIME)
 31 
 32 static int setfl(int fd, struct file * filp, unsigned long arg)
 33 {
 34         struct inode * inode = file_inode(filp);
 35         int error = 0;
 36 
 37         /*
 38          * O_APPEND cannot be cleared if the file is marked as append-only
 39          * and the file is open for write.
 40          */
 41         if (((arg ^ filp->f_flags) & O_APPEND) && IS_APPEND(inode))
 42                 return -EPERM;
 43 
 44         /* O_NOATIME can only be set by the owner or superuser */
 45         if ((arg & O_NOATIME) && !(filp->f_flags & O_NOATIME))
 46                 if (!inode_owner_or_capable(inode))
 47                         return -EPERM;
 48 
 49         /* required for strict SunOS emulation */
 50         if (O_NONBLOCK != O_NDELAY)
 51                if (arg & O_NDELAY)
 52                    arg |= O_NONBLOCK;
 53 
 54         /* Pipe packetized mode is controlled by O_DIRECT flag */
 55         if (!S_ISFIFO(inode->i_mode) && (arg & O_DIRECT)) {
 56                 if (!filp->f_mapping || !filp->f_mapping->a_ops ||
 57                         !filp->f_mapping->a_ops->direct_IO)
 58                                 return -EINVAL;
 59         }
 60 
 61         if (filp->f_op->check_flags)
 62                 error = filp->f_op->check_flags(arg);
 63         if (error)
 64                 return error;
 65 
 66         /*
 67          * ->fasync() is responsible for setting the FASYNC bit.
 68          */
 69         if (((arg ^ filp->f_flags) & FASYNC) && filp->f_op->fasync) {
 70                 error = filp->f_op->fasync(fd, filp, (arg & FASYNC) != 0);
 71                 if (error < 0)
 72                         goto out;
 73                 if (error > 0)
 74                         error = 0;
 75         }
 76         spin_lock(&filp->f_lock);
 77         filp->f_flags = (arg & SETFL_MASK) | (filp->f_flags & ~SETFL_MASK);
 78         spin_unlock(&filp->f_lock);
 79 
 80  out:
 81         return error;
 82 }
 83 
 84 static void f_modown(struct file *filp, struct pid *pid, enum pid_type type,
 85                      int force)
 86 {
 87         write_lock_irq(&filp->f_owner.lock);
 88         if (force || !filp->f_owner.pid) {
 89                 put_pid(filp->f_owner.pid);
 90                 filp->f_owner.pid = get_pid(pid);
 91                 filp->f_owner.pid_type = type;
 92 
 93                 if (pid) {
 94                         const struct cred *cred = current_cred();
 95                         filp->f_owner.uid = cred->uid;
 96                         filp->f_owner.euid = cred->euid;
 97                 }
 98         }
 99         write_unlock_irq(&filp->f_owner.lock);
100 }
101 
102 void __f_setown(struct file *filp, struct pid *pid, enum pid_type type,
103                 int force)
104 {
105         security_file_set_fowner(filp);
106         f_modown(filp, pid, type, force);
107 }
108 EXPORT_SYMBOL(__f_setown);
109 
110 void f_setown(struct file *filp, unsigned long arg, int force)
111 {
112         enum pid_type type;
113         struct pid *pid;
114         int who = arg;
115         type = PIDTYPE_PID;
116         if (who < 0) {
117                 type = PIDTYPE_PGID;
118                 who = -who;
119         }
120         rcu_read_lock();
121         pid = find_vpid(who);
122         __f_setown(filp, pid, type, force);
123         rcu_read_unlock();
124 }
125 EXPORT_SYMBOL(f_setown);
126 
127 void f_delown(struct file *filp)
128 {
129         f_modown(filp, NULL, PIDTYPE_PID, 1);
130 }
131 
132 pid_t f_getown(struct file *filp)
133 {
134         pid_t pid;
135         read_lock(&filp->f_owner.lock);
136         pid = pid_vnr(filp->f_owner.pid);
137         if (filp->f_owner.pid_type == PIDTYPE_PGID)
138                 pid = -pid;
139         read_unlock(&filp->f_owner.lock);
140         return pid;
141 }
142 
143 static int f_setown_ex(struct file *filp, unsigned long arg)
144 {
145         struct f_owner_ex __user *owner_p = (void __user *)arg;
146         struct f_owner_ex owner;
147         struct pid *pid;
148         int type;
149         int ret;
150 
151         ret = copy_from_user(&owner, owner_p, sizeof(owner));
152         if (ret)
153                 return -EFAULT;
154 
155         switch (owner.type) {
156         case F_OWNER_TID:
157                 type = PIDTYPE_MAX;
158                 break;
159 
160         case F_OWNER_PID:
161                 type = PIDTYPE_PID;
162                 break;
163 
164         case F_OWNER_PGRP:
165                 type = PIDTYPE_PGID;
166                 break;
167 
168         default:
169                 return -EINVAL;
170         }
171 
172         rcu_read_lock();
173         pid = find_vpid(owner.pid);
174         if (owner.pid && !pid)
175                 ret = -ESRCH;
176         else
177                  __f_setown(filp, pid, type, 1);
178         rcu_read_unlock();
179 
180         return ret;
181 }
182 
183 static int f_getown_ex(struct file *filp, unsigned long arg)
184 {
185         struct f_owner_ex __user *owner_p = (void __user *)arg;
186         struct f_owner_ex owner;
187         int ret = 0;
188 
189         read_lock(&filp->f_owner.lock);
190         owner.pid = pid_vnr(filp->f_owner.pid);
191         switch (filp->f_owner.pid_type) {
192         case PIDTYPE_MAX:
193                 owner.type = F_OWNER_TID;
194                 break;
195 
196         case PIDTYPE_PID:
197                 owner.type = F_OWNER_PID;
198                 break;
199 
200         case PIDTYPE_PGID:
201                 owner.type = F_OWNER_PGRP;
202                 break;
203 
204         default:
205                 WARN_ON(1);
206                 ret = -EINVAL;
207                 break;
208         }
209         read_unlock(&filp->f_owner.lock);
210 
211         if (!ret) {
212                 ret = copy_to_user(owner_p, &owner, sizeof(owner));
213                 if (ret)
214                         ret = -EFAULT;
215         }
216         return ret;
217 }
218 
219 #ifdef CONFIG_CHECKPOINT_RESTORE
220 static int f_getowner_uids(struct file *filp, unsigned long arg)
221 {
222         struct user_namespace *user_ns = current_user_ns();
223         uid_t __user *dst = (void __user *)arg;
224         uid_t src[2];
225         int err;
226 
227         read_lock(&filp->f_owner.lock);
228         src[0] = from_kuid(user_ns, filp->f_owner.uid);
229         src[1] = from_kuid(user_ns, filp->f_owner.euid);
230         read_unlock(&filp->f_owner.lock);
231 
232         err  = put_user(src[0], &dst[0]);
233         err |= put_user(src[1], &dst[1]);
234 
235         return err;
236 }
237 #else
238 static int f_getowner_uids(struct file *filp, unsigned long arg)
239 {
240         return -EINVAL;
241 }
242 #endif
243 
244 static long do_fcntl(int fd, unsigned int cmd, unsigned long arg,
245                 struct file *filp)
246 {
247         long err = -EINVAL;
248 
249         switch (cmd) {
250         case F_DUPFD:
251                 err = f_dupfd(arg, filp, 0);
252                 break;
253         case F_DUPFD_CLOEXEC:
254                 err = f_dupfd(arg, filp, O_CLOEXEC);
255                 break;
256         case F_GETFD:
257                 err = get_close_on_exec(fd) ? FD_CLOEXEC : 0;
258                 break;
259         case F_SETFD:
260                 err = 0;
261                 set_close_on_exec(fd, arg & FD_CLOEXEC);
262                 break;
263         case F_GETFL:
264                 err = filp->f_flags;
265                 break;
266         case F_SETFL:
267                 err = setfl(fd, filp, arg);
268                 break;
269 #if BITS_PER_LONG != 32
270         /* 32-bit arches must use fcntl64() */
271         case F_OFD_GETLK:
272 #endif
273         case F_GETLK:
274                 err = fcntl_getlk(filp, cmd, (struct flock __user *) arg);
275                 break;
276 #if BITS_PER_LONG != 32
277         /* 32-bit arches must use fcntl64() */
278         case F_OFD_SETLK:
279         case F_OFD_SETLKW:
280 #endif
281                 /* Fallthrough */
282         case F_SETLK:
283         case F_SETLKW:
284                 err = fcntl_setlk(fd, filp, cmd, (struct flock __user *) arg);
285                 break;
286         case F_GETOWN:
287                 /*
288                  * XXX If f_owner is a process group, the
289                  * negative return value will get converted
290                  * into an error.  Oops.  If we keep the
291                  * current syscall conventions, the only way
292                  * to fix this will be in libc.
293                  */
294                 err = f_getown(filp);
295                 force_successful_syscall_return();
296                 break;
297         case F_SETOWN:
298                 f_setown(filp, arg, 1);
299                 err = 0;
300                 break;
301         case F_GETOWN_EX:
302                 err = f_getown_ex(filp, arg);
303                 break;
304         case F_SETOWN_EX:
305                 err = f_setown_ex(filp, arg);
306                 break;
307         case F_GETOWNER_UIDS:
308                 err = f_getowner_uids(filp, arg);
309                 break;
310         case F_GETSIG:
311                 err = filp->f_owner.signum;
312                 break;
313         case F_SETSIG:
314                 /* arg == 0 restores default behaviour. */
315                 if (!valid_signal(arg)) {
316                         break;
317                 }
318                 err = 0;
319                 filp->f_owner.signum = arg;
320                 break;
321         case F_GETLEASE:
322                 err = fcntl_getlease(filp);
323                 break;
324         case F_SETLEASE:
325                 err = fcntl_setlease(fd, filp, arg);
326                 break;
327         case F_NOTIFY:
328                 err = fcntl_dirnotify(fd, filp, arg);
329                 break;
330         case F_SETPIPE_SZ:
331         case F_GETPIPE_SZ:
332                 err = pipe_fcntl(filp, cmd, arg);
333                 break;
334         case F_ADD_SEALS:
335         case F_GET_SEALS:
336                 err = shmem_fcntl(filp, cmd, arg);
337                 break;
338         default:
339                 break;
340         }
341         return err;
342 }
343 
344 static int check_fcntl_cmd(unsigned cmd)
345 {
346         switch (cmd) {
347         case F_DUPFD:
348         case F_DUPFD_CLOEXEC:
349         case F_GETFD:
350         case F_SETFD:
351         case F_GETFL:
352                 return 1;
353         }
354         return 0;
355 }
356 
357 SYSCALL_DEFINE3(fcntl, unsigned int, fd, unsigned int, cmd, unsigned long, arg)
358 {       
359         struct fd f = fdget_raw(fd);
360         long err = -EBADF;
361 
362         if (!f.file)
363                 goto out;
364 
365         if (unlikely(f.file->f_mode & FMODE_PATH)) {
366                 if (!check_fcntl_cmd(cmd))
367                         goto out1;
368         }
369 
370         err = security_file_fcntl(f.file, cmd, arg);
371         if (!err)
372                 err = do_fcntl(fd, cmd, arg, f.file);
373 
374 out1:
375         fdput(f);
376 out:
377         return err;
378 }
379 
380 #if BITS_PER_LONG == 32
381 SYSCALL_DEFINE3(fcntl64, unsigned int, fd, unsigned int, cmd,
382                 unsigned long, arg)
383 {       
384         struct fd f = fdget_raw(fd);
385         long err = -EBADF;
386 
387         if (!f.file)
388                 goto out;
389 
390         if (unlikely(f.file->f_mode & FMODE_PATH)) {
391                 if (!check_fcntl_cmd(cmd))
392                         goto out1;
393         }
394 
395         err = security_file_fcntl(f.file, cmd, arg);
396         if (err)
397                 goto out1;
398         
399         switch (cmd) {
400         case F_GETLK64:
401         case F_OFD_GETLK:
402                 err = fcntl_getlk64(f.file, cmd, (struct flock64 __user *) arg);
403                 break;
404         case F_SETLK64:
405         case F_SETLKW64:
406         case F_OFD_SETLK:
407         case F_OFD_SETLKW:
408                 err = fcntl_setlk64(fd, f.file, cmd,
409                                 (struct flock64 __user *) arg);
410                 break;
411         default:
412                 err = do_fcntl(fd, cmd, arg, f.file);
413                 break;
414         }
415 out1:
416         fdput(f);
417 out:
418         return err;
419 }
420 #endif
421 
422 /* Table to convert sigio signal codes into poll band bitmaps */
423 
424 static const long band_table[NSIGPOLL] = {
425         POLLIN | POLLRDNORM,                    /* POLL_IN */
426         POLLOUT | POLLWRNORM | POLLWRBAND,      /* POLL_OUT */
427         POLLIN | POLLRDNORM | POLLMSG,          /* POLL_MSG */
428         POLLERR,                                /* POLL_ERR */
429         POLLPRI | POLLRDBAND,                   /* POLL_PRI */
430         POLLHUP | POLLERR                       /* POLL_HUP */
431 };
432 
433 static inline int sigio_perm(struct task_struct *p,
434                              struct fown_struct *fown, int sig)
435 {
436         const struct cred *cred;
437         int ret;
438 
439         rcu_read_lock();
440         cred = __task_cred(p);
441         ret = ((uid_eq(fown->euid, GLOBAL_ROOT_UID) ||
442                 uid_eq(fown->euid, cred->suid) || uid_eq(fown->euid, cred->uid) ||
443                 uid_eq(fown->uid,  cred->suid) || uid_eq(fown->uid,  cred->uid)) &&
444                !security_file_send_sigiotask(p, fown, sig));
445         rcu_read_unlock();
446         return ret;
447 }
448 
449 static void send_sigio_to_task(struct task_struct *p,
450                                struct fown_struct *fown,
451                                int fd, int reason, int group)
452 {
453         /*
454          * F_SETSIG can change ->signum lockless in parallel, make
455          * sure we read it once and use the same value throughout.
456          */
457         int signum = ACCESS_ONCE(fown->signum);
458 
459         if (!sigio_perm(p, fown, signum))
460                 return;
461 
462         switch (signum) {
463                 siginfo_t si;
464                 default:
465                         /* Queue a rt signal with the appropriate fd as its
466                            value.  We use SI_SIGIO as the source, not 
467                            SI_KERNEL, since kernel signals always get 
468                            delivered even if we can't queue.  Failure to
469                            queue in this case _should_ be reported; we fall
470                            back to SIGIO in that case. --sct */
471                         si.si_signo = signum;
472                         si.si_errno = 0;
473                         si.si_code  = reason;
474                         /* Make sure we are called with one of the POLL_*
475                            reasons, otherwise we could leak kernel stack into
476                            userspace.  */
477                         BUG_ON((reason & __SI_MASK) != __SI_POLL);
478                         if (reason - POLL_IN >= NSIGPOLL)
479                                 si.si_band  = ~0L;
480                         else
481                                 si.si_band = band_table[reason - POLL_IN];
482                         si.si_fd    = fd;
483                         if (!do_send_sig_info(signum, &si, p, group))
484                                 break;
485                 /* fall-through: fall back on the old plain SIGIO signal */
486                 case 0:
487                         do_send_sig_info(SIGIO, SEND_SIG_PRIV, p, group);
488         }
489 }
490 
491 void send_sigio(struct fown_struct *fown, int fd, int band)
492 {
493         struct task_struct *p;
494         enum pid_type type;
495         struct pid *pid;
496         int group = 1;
497         
498         read_lock(&fown->lock);
499 
500         type = fown->pid_type;
501         if (type == PIDTYPE_MAX) {
502                 group = 0;
503                 type = PIDTYPE_PID;
504         }
505 
506         pid = fown->pid;
507         if (!pid)
508                 goto out_unlock_fown;
509         
510         read_lock(&tasklist_lock);
511         do_each_pid_task(pid, type, p) {
512                 send_sigio_to_task(p, fown, fd, band, group);
513         } while_each_pid_task(pid, type, p);
514         read_unlock(&tasklist_lock);
515  out_unlock_fown:
516         read_unlock(&fown->lock);
517 }
518 
519 static void send_sigurg_to_task(struct task_struct *p,
520                                 struct fown_struct *fown, int group)
521 {
522         if (sigio_perm(p, fown, SIGURG))
523                 do_send_sig_info(SIGURG, SEND_SIG_PRIV, p, group);
524 }
525 
526 int send_sigurg(struct fown_struct *fown)
527 {
528         struct task_struct *p;
529         enum pid_type type;
530         struct pid *pid;
531         int group = 1;
532         int ret = 0;
533         
534         read_lock(&fown->lock);
535 
536         type = fown->pid_type;
537         if (type == PIDTYPE_MAX) {
538                 group = 0;
539                 type = PIDTYPE_PID;
540         }
541 
542         pid = fown->pid;
543         if (!pid)
544                 goto out_unlock_fown;
545 
546         ret = 1;
547         
548         read_lock(&tasklist_lock);
549         do_each_pid_task(pid, type, p) {
550                 send_sigurg_to_task(p, fown, group);
551         } while_each_pid_task(pid, type, p);
552         read_unlock(&tasklist_lock);
553  out_unlock_fown:
554         read_unlock(&fown->lock);
555         return ret;
556 }
557 
558 static DEFINE_SPINLOCK(fasync_lock);
559 static struct kmem_cache *fasync_cache __read_mostly;
560 
561 static void fasync_free_rcu(struct rcu_head *head)
562 {
563         kmem_cache_free(fasync_cache,
564                         container_of(head, struct fasync_struct, fa_rcu));
565 }
566 
567 /*
568  * Remove a fasync entry. If successfully removed, return
569  * positive and clear the FASYNC flag. If no entry exists,
570  * do nothing and return 0.
571  *
572  * NOTE! It is very important that the FASYNC flag always
573  * match the state "is the filp on a fasync list".
574  *
575  */
576 int fasync_remove_entry(struct file *filp, struct fasync_struct **fapp)
577 {
578         struct fasync_struct *fa, **fp;
579         int result = 0;
580 
581         spin_lock(&filp->f_lock);
582         spin_lock(&fasync_lock);
583         for (fp = fapp; (fa = *fp) != NULL; fp = &fa->fa_next) {
584                 if (fa->fa_file != filp)
585                         continue;
586 
587                 spin_lock_irq(&fa->fa_lock);
588                 fa->fa_file = NULL;
589                 spin_unlock_irq(&fa->fa_lock);
590 
591                 *fp = fa->fa_next;
592                 call_rcu(&fa->fa_rcu, fasync_free_rcu);
593                 filp->f_flags &= ~FASYNC;
594                 result = 1;
595                 break;
596         }
597         spin_unlock(&fasync_lock);
598         spin_unlock(&filp->f_lock);
599         return result;
600 }
601 
602 struct fasync_struct *fasync_alloc(void)
603 {
604         return kmem_cache_alloc(fasync_cache, GFP_KERNEL);
605 }
606 
607 /*
608  * NOTE! This can be used only for unused fasync entries:
609  * entries that actually got inserted on the fasync list
610  * need to be released by rcu - see fasync_remove_entry.
611  */
612 void fasync_free(struct fasync_struct *new)
613 {
614         kmem_cache_free(fasync_cache, new);
615 }
616 
617 /*
618  * Insert a new entry into the fasync list.  Return the pointer to the
619  * old one if we didn't use the new one.
620  *
621  * NOTE! It is very important that the FASYNC flag always
622  * match the state "is the filp on a fasync list".
623  */
624 struct fasync_struct *fasync_insert_entry(int fd, struct file *filp, struct fasync_struct **fapp, struct fasync_struct *new)
625 {
626         struct fasync_struct *fa, **fp;
627 
628         spin_lock(&filp->f_lock);
629         spin_lock(&fasync_lock);
630         for (fp = fapp; (fa = *fp) != NULL; fp = &fa->fa_next) {
631                 if (fa->fa_file != filp)
632                         continue;
633 
634                 spin_lock_irq(&fa->fa_lock);
635                 fa->fa_fd = fd;
636                 spin_unlock_irq(&fa->fa_lock);
637                 goto out;
638         }
639 
640         spin_lock_init(&new->fa_lock);
641         new->magic = FASYNC_MAGIC;
642         new->fa_file = filp;
643         new->fa_fd = fd;
644         new->fa_next = *fapp;
645         rcu_assign_pointer(*fapp, new);
646         filp->f_flags |= FASYNC;
647 
648 out:
649         spin_unlock(&fasync_lock);
650         spin_unlock(&filp->f_lock);
651         return fa;
652 }
653 
654 /*
655  * Add a fasync entry. Return negative on error, positive if
656  * added, and zero if did nothing but change an existing one.
657  */
658 static int fasync_add_entry(int fd, struct file *filp, struct fasync_struct **fapp)
659 {
660         struct fasync_struct *new;
661 
662         new = fasync_alloc();
663         if (!new)
664                 return -ENOMEM;
665 
666         /*
667          * fasync_insert_entry() returns the old (update) entry if
668          * it existed.
669          *
670          * So free the (unused) new entry and return 0 to let the
671          * caller know that we didn't add any new fasync entries.
672          */
673         if (fasync_insert_entry(fd, filp, fapp, new)) {
674                 fasync_free(new);
675                 return 0;
676         }
677 
678         return 1;
679 }
680 
681 /*
682  * fasync_helper() is used by almost all character device drivers
683  * to set up the fasync queue, and for regular files by the file
684  * lease code. It returns negative on error, 0 if it did no changes
685  * and positive if it added/deleted the entry.
686  */
687 int fasync_helper(int fd, struct file * filp, int on, struct fasync_struct **fapp)
688 {
689         if (!on)
690                 return fasync_remove_entry(filp, fapp);
691         return fasync_add_entry(fd, filp, fapp);
692 }
693 
694 EXPORT_SYMBOL(fasync_helper);
695 
696 /*
697  * rcu_read_lock() is held
698  */
699 static void kill_fasync_rcu(struct fasync_struct *fa, int sig, int band)
700 {
701         while (fa) {
702                 struct fown_struct *fown;
703                 unsigned long flags;
704 
705                 if (fa->magic != FASYNC_MAGIC) {
706                         printk(KERN_ERR "kill_fasync: bad magic number in "
707                                "fasync_struct!\n");
708                         return;
709                 }
710                 spin_lock_irqsave(&fa->fa_lock, flags);
711                 if (fa->fa_file) {
712                         fown = &fa->fa_file->f_owner;
713                         /* Don't send SIGURG to processes which have not set a
714                            queued signum: SIGURG has its own default signalling
715                            mechanism. */
716                         if (!(sig == SIGURG && fown->signum == 0))
717                                 send_sigio(fown, fa->fa_fd, band);
718                 }
719                 spin_unlock_irqrestore(&fa->fa_lock, flags);
720                 fa = rcu_dereference(fa->fa_next);
721         }
722 }
723 
724 void kill_fasync(struct fasync_struct **fp, int sig, int band)
725 {
726         /* First a quick test without locking: usually
727          * the list is empty.
728          */
729         if (*fp) {
730                 rcu_read_lock();
731                 kill_fasync_rcu(rcu_dereference(*fp), sig, band);
732                 rcu_read_unlock();
733         }
734 }
735 EXPORT_SYMBOL(kill_fasync);
736 
737 static int __init fcntl_init(void)
738 {
739         /*
740          * Please add new bits here to ensure allocation uniqueness.
741          * Exceptions: O_NONBLOCK is a two bit define on parisc; O_NDELAY
742          * is defined as O_NONBLOCK on some platforms and not on others.
743          */
744         BUILD_BUG_ON(21 - 1 /* for O_RDONLY being 0 */ != HWEIGHT32(
745                 O_RDONLY        | O_WRONLY      | O_RDWR        |
746                 O_CREAT         | O_EXCL        | O_NOCTTY      |
747                 O_TRUNC         | O_APPEND      | /* O_NONBLOCK | */
748                 __O_SYNC        | O_DSYNC       | FASYNC        |
749                 O_DIRECT        | O_LARGEFILE   | O_DIRECTORY   |
750                 O_NOFOLLOW      | O_NOATIME     | O_CLOEXEC     |
751                 __FMODE_EXEC    | O_PATH        | __O_TMPFILE   |
752                 __FMODE_NONOTIFY
753                 ));
754 
755         fasync_cache = kmem_cache_create("fasync_cache",
756                 sizeof(struct fasync_struct), 0, SLAB_PANIC, NULL);
757         return 0;
758 }
759 
760 module_init(fcntl_init)
761 

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