Root/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
24#include <asm/poll.h>
25#include <asm/siginfo.h>
26#include <asm/uaccess.h>
27
28void set_close_on_exec(unsigned int fd, int flag)
29{
30    struct files_struct *files = current->files;
31    struct fdtable *fdt;
32    spin_lock(&files->file_lock);
33    fdt = files_fdtable(files);
34    if (flag)
35        FD_SET(fd, fdt->close_on_exec);
36    else
37        FD_CLR(fd, fdt->close_on_exec);
38    spin_unlock(&files->file_lock);
39}
40
41static int get_close_on_exec(unsigned int fd)
42{
43    struct files_struct *files = current->files;
44    struct fdtable *fdt;
45    int res;
46    rcu_read_lock();
47    fdt = files_fdtable(files);
48    res = FD_ISSET(fd, fdt->close_on_exec);
49    rcu_read_unlock();
50    return res;
51}
52
53SYSCALL_DEFINE3(dup3, unsigned int, oldfd, unsigned int, newfd, int, flags)
54{
55    int err = -EBADF;
56    struct file * file, *tofree;
57    struct files_struct * files = current->files;
58    struct fdtable *fdt;
59
60    if ((flags & ~O_CLOEXEC) != 0)
61        return -EINVAL;
62
63    if (unlikely(oldfd == newfd))
64        return -EINVAL;
65
66    spin_lock(&files->file_lock);
67    err = expand_files(files, newfd);
68    file = fcheck(oldfd);
69    if (unlikely(!file))
70        goto Ebadf;
71    if (unlikely(err < 0)) {
72        if (err == -EMFILE)
73            goto Ebadf;
74        goto out_unlock;
75    }
76    /*
77     * We need to detect attempts to do dup2() over allocated but still
78     * not finished descriptor. NB: OpenBSD avoids that at the price of
79     * extra work in their equivalent of fget() - they insert struct
80     * file immediately after grabbing descriptor, mark it larval if
81     * more work (e.g. actual opening) is needed and make sure that
82     * fget() treats larval files as absent. Potentially interesting,
83     * but while extra work in fget() is trivial, locking implications
84     * and amount of surgery on open()-related paths in VFS are not.
85     * FreeBSD fails with -EBADF in the same situation, NetBSD "solution"
86     * deadlocks in rather amusing ways, AFAICS. All of that is out of
87     * scope of POSIX or SUS, since neither considers shared descriptor
88     * tables and this condition does not arise without those.
89     */
90    err = -EBUSY;
91    fdt = files_fdtable(files);
92    tofree = fdt->fd[newfd];
93    if (!tofree && FD_ISSET(newfd, fdt->open_fds))
94        goto out_unlock;
95    get_file(file);
96    rcu_assign_pointer(fdt->fd[newfd], file);
97    FD_SET(newfd, fdt->open_fds);
98    if (flags & O_CLOEXEC)
99        FD_SET(newfd, fdt->close_on_exec);
100    else
101        FD_CLR(newfd, fdt->close_on_exec);
102    spin_unlock(&files->file_lock);
103
104    if (tofree)
105        filp_close(tofree, files);
106
107    return newfd;
108
109Ebadf:
110    err = -EBADF;
111out_unlock:
112    spin_unlock(&files->file_lock);
113    return err;
114}
115
116SYSCALL_DEFINE2(dup2, unsigned int, oldfd, unsigned int, newfd)
117{
118    if (unlikely(newfd == oldfd)) { /* corner case */
119        struct files_struct *files = current->files;
120        int retval = oldfd;
121
122        rcu_read_lock();
123        if (!fcheck_files(files, oldfd))
124            retval = -EBADF;
125        rcu_read_unlock();
126        return retval;
127    }
128    return sys_dup3(oldfd, newfd, 0);
129}
130
131SYSCALL_DEFINE1(dup, unsigned int, fildes)
132{
133    int ret = -EBADF;
134    struct file *file = fget_raw(fildes);
135
136    if (file) {
137        ret = get_unused_fd();
138        if (ret >= 0)
139            fd_install(ret, file);
140        else
141            fput(file);
142    }
143    return ret;
144}
145
146#define SETFL_MASK (O_APPEND | O_NONBLOCK | O_NDELAY | O_DIRECT | O_NOATIME)
147
148static int setfl(int fd, struct file * filp, unsigned long arg)
149{
150    struct inode * inode = filp->f_path.dentry->d_inode;
151    int error = 0;
152
153    /*
154     * O_APPEND cannot be cleared if the file is marked as append-only
155     * and the file is open for write.
156     */
157    if (((arg ^ filp->f_flags) & O_APPEND) && IS_APPEND(inode))
158        return -EPERM;
159
160    /* O_NOATIME can only be set by the owner or superuser */
161    if ((arg & O_NOATIME) && !(filp->f_flags & O_NOATIME))
162        if (!inode_owner_or_capable(inode))
163            return -EPERM;
164
165    /* required for strict SunOS emulation */
166    if (O_NONBLOCK != O_NDELAY)
167           if (arg & O_NDELAY)
168           arg |= O_NONBLOCK;
169
170    if (arg & O_DIRECT) {
171        if (!filp->f_mapping || !filp->f_mapping->a_ops ||
172            !filp->f_mapping->a_ops->direct_IO)
173                return -EINVAL;
174    }
175
176    if (filp->f_op && filp->f_op->check_flags)
177        error = filp->f_op->check_flags(arg);
178    if (error)
179        return error;
180
181    /*
182     * ->fasync() is responsible for setting the FASYNC bit.
183     */
184    if (((arg ^ filp->f_flags) & FASYNC) && filp->f_op &&
185            filp->f_op->fasync) {
186        error = filp->f_op->fasync(fd, filp, (arg & FASYNC) != 0);
187        if (error < 0)
188            goto out;
189        if (error > 0)
190            error = 0;
191    }
192    spin_lock(&filp->f_lock);
193    filp->f_flags = (arg & SETFL_MASK) | (filp->f_flags & ~SETFL_MASK);
194    spin_unlock(&filp->f_lock);
195
196 out:
197    return error;
198}
199
200static void f_modown(struct file *filp, struct pid *pid, enum pid_type type,
201                     int force)
202{
203    write_lock_irq(&filp->f_owner.lock);
204    if (force || !filp->f_owner.pid) {
205        put_pid(filp->f_owner.pid);
206        filp->f_owner.pid = get_pid(pid);
207        filp->f_owner.pid_type = type;
208
209        if (pid) {
210            const struct cred *cred = current_cred();
211            filp->f_owner.uid = cred->uid;
212            filp->f_owner.euid = cred->euid;
213        }
214    }
215    write_unlock_irq(&filp->f_owner.lock);
216}
217
218int __f_setown(struct file *filp, struct pid *pid, enum pid_type type,
219        int force)
220{
221    int err;
222
223    err = security_file_set_fowner(filp);
224    if (err)
225        return err;
226
227    f_modown(filp, pid, type, force);
228    return 0;
229}
230EXPORT_SYMBOL(__f_setown);
231
232int f_setown(struct file *filp, unsigned long arg, int force)
233{
234    enum pid_type type;
235    struct pid *pid;
236    int who = arg;
237    int result;
238    type = PIDTYPE_PID;
239    if (who < 0) {
240        type = PIDTYPE_PGID;
241        who = -who;
242    }
243    rcu_read_lock();
244    pid = find_vpid(who);
245    result = __f_setown(filp, pid, type, force);
246    rcu_read_unlock();
247    return result;
248}
249EXPORT_SYMBOL(f_setown);
250
251void f_delown(struct file *filp)
252{
253    f_modown(filp, NULL, PIDTYPE_PID, 1);
254}
255
256pid_t f_getown(struct file *filp)
257{
258    pid_t pid;
259    read_lock(&filp->f_owner.lock);
260    pid = pid_vnr(filp->f_owner.pid);
261    if (filp->f_owner.pid_type == PIDTYPE_PGID)
262        pid = -pid;
263    read_unlock(&filp->f_owner.lock);
264    return pid;
265}
266
267static int f_setown_ex(struct file *filp, unsigned long arg)
268{
269    struct f_owner_ex * __user owner_p = (void * __user)arg;
270    struct f_owner_ex owner;
271    struct pid *pid;
272    int type;
273    int ret;
274
275    ret = copy_from_user(&owner, owner_p, sizeof(owner));
276    if (ret)
277        return -EFAULT;
278
279    switch (owner.type) {
280    case F_OWNER_TID:
281        type = PIDTYPE_MAX;
282        break;
283
284    case F_OWNER_PID:
285        type = PIDTYPE_PID;
286        break;
287
288    case F_OWNER_PGRP:
289        type = PIDTYPE_PGID;
290        break;
291
292    default:
293        return -EINVAL;
294    }
295
296    rcu_read_lock();
297    pid = find_vpid(owner.pid);
298    if (owner.pid && !pid)
299        ret = -ESRCH;
300    else
301        ret = __f_setown(filp, pid, type, 1);
302    rcu_read_unlock();
303
304    return ret;
305}
306
307static int f_getown_ex(struct file *filp, unsigned long arg)
308{
309    struct f_owner_ex * __user owner_p = (void * __user)arg;
310    struct f_owner_ex owner;
311    int ret = 0;
312
313    read_lock(&filp->f_owner.lock);
314    owner.pid = pid_vnr(filp->f_owner.pid);
315    switch (filp->f_owner.pid_type) {
316    case PIDTYPE_MAX:
317        owner.type = F_OWNER_TID;
318        break;
319
320    case PIDTYPE_PID:
321        owner.type = F_OWNER_PID;
322        break;
323
324    case PIDTYPE_PGID:
325        owner.type = F_OWNER_PGRP;
326        break;
327
328    default:
329        WARN_ON(1);
330        ret = -EINVAL;
331        break;
332    }
333    read_unlock(&filp->f_owner.lock);
334
335    if (!ret) {
336        ret = copy_to_user(owner_p, &owner, sizeof(owner));
337        if (ret)
338            ret = -EFAULT;
339    }
340    return ret;
341}
342
343static long do_fcntl(int fd, unsigned int cmd, unsigned long arg,
344        struct file *filp)
345{
346    long err = -EINVAL;
347
348    switch (cmd) {
349    case F_DUPFD:
350    case F_DUPFD_CLOEXEC:
351        if (arg >= rlimit(RLIMIT_NOFILE))
352            break;
353        err = alloc_fd(arg, cmd == F_DUPFD_CLOEXEC ? O_CLOEXEC : 0);
354        if (err >= 0) {
355            get_file(filp);
356            fd_install(err, filp);
357        }
358        break;
359    case F_GETFD:
360        err = get_close_on_exec(fd) ? FD_CLOEXEC : 0;
361        break;
362    case F_SETFD:
363        err = 0;
364        set_close_on_exec(fd, arg & FD_CLOEXEC);
365        break;
366    case F_GETFL:
367        err = filp->f_flags;
368        break;
369    case F_SETFL:
370        err = setfl(fd, filp, arg);
371        break;
372    case F_GETLK:
373        err = fcntl_getlk(filp, (struct flock __user *) arg);
374        break;
375    case F_SETLK:
376    case F_SETLKW:
377        err = fcntl_setlk(fd, filp, cmd, (struct flock __user *) arg);
378        break;
379    case F_GETOWN:
380        /*
381         * XXX If f_owner is a process group, the
382         * negative return value will get converted
383         * into an error. Oops. If we keep the
384         * current syscall conventions, the only way
385         * to fix this will be in libc.
386         */
387        err = f_getown(filp);
388        force_successful_syscall_return();
389        break;
390    case F_SETOWN:
391        err = f_setown(filp, arg, 1);
392        break;
393    case F_GETOWN_EX:
394        err = f_getown_ex(filp, arg);
395        break;
396    case F_SETOWN_EX:
397        err = f_setown_ex(filp, arg);
398        break;
399    case F_GETSIG:
400        err = filp->f_owner.signum;
401        break;
402    case F_SETSIG:
403        /* arg == 0 restores default behaviour. */
404        if (!valid_signal(arg)) {
405            break;
406        }
407        err = 0;
408        filp->f_owner.signum = arg;
409        break;
410    case F_GETLEASE:
411        err = fcntl_getlease(filp);
412        break;
413    case F_SETLEASE:
414        err = fcntl_setlease(fd, filp, arg);
415        break;
416    case F_NOTIFY:
417        err = fcntl_dirnotify(fd, filp, arg);
418        break;
419    case F_SETPIPE_SZ:
420    case F_GETPIPE_SZ:
421        err = pipe_fcntl(filp, cmd, arg);
422        break;
423    default:
424        break;
425    }
426    return err;
427}
428
429static int check_fcntl_cmd(unsigned cmd)
430{
431    switch (cmd) {
432    case F_DUPFD:
433    case F_DUPFD_CLOEXEC:
434    case F_GETFD:
435    case F_SETFD:
436    case F_GETFL:
437        return 1;
438    }
439    return 0;
440}
441
442SYSCALL_DEFINE3(fcntl, unsigned int, fd, unsigned int, cmd, unsigned long, arg)
443{
444    struct file *filp;
445    long err = -EBADF;
446
447    filp = fget_raw(fd);
448    if (!filp)
449        goto out;
450
451    if (unlikely(filp->f_mode & FMODE_PATH)) {
452        if (!check_fcntl_cmd(cmd)) {
453            fput(filp);
454            goto out;
455        }
456    }
457
458    err = security_file_fcntl(filp, cmd, arg);
459    if (err) {
460        fput(filp);
461        return err;
462    }
463
464    err = do_fcntl(fd, cmd, arg, filp);
465
466     fput(filp);
467out:
468    return err;
469}
470
471#if BITS_PER_LONG == 32
472SYSCALL_DEFINE3(fcntl64, unsigned int, fd, unsigned int, cmd,
473        unsigned long, arg)
474{
475    struct file * filp;
476    long err;
477
478    err = -EBADF;
479    filp = fget_raw(fd);
480    if (!filp)
481        goto out;
482
483    if (unlikely(filp->f_mode & FMODE_PATH)) {
484        if (!check_fcntl_cmd(cmd)) {
485            fput(filp);
486            goto out;
487        }
488    }
489
490    err = security_file_fcntl(filp, cmd, arg);
491    if (err) {
492        fput(filp);
493        return err;
494    }
495    err = -EBADF;
496    
497    switch (cmd) {
498        case F_GETLK64:
499            err = fcntl_getlk64(filp, (struct flock64 __user *) arg);
500            break;
501        case F_SETLK64:
502        case F_SETLKW64:
503            err = fcntl_setlk64(fd, filp, cmd,
504                    (struct flock64 __user *) arg);
505            break;
506        default:
507            err = do_fcntl(fd, cmd, arg, filp);
508            break;
509    }
510    fput(filp);
511out:
512    return err;
513}
514#endif
515
516/* Table to convert sigio signal codes into poll band bitmaps */
517
518static const long band_table[NSIGPOLL] = {
519    POLLIN | POLLRDNORM, /* POLL_IN */
520    POLLOUT | POLLWRNORM | POLLWRBAND, /* POLL_OUT */
521    POLLIN | POLLRDNORM | POLLMSG, /* POLL_MSG */
522    POLLERR, /* POLL_ERR */
523    POLLPRI | POLLRDBAND, /* POLL_PRI */
524    POLLHUP | POLLERR /* POLL_HUP */
525};
526
527static inline int sigio_perm(struct task_struct *p,
528                             struct fown_struct *fown, int sig)
529{
530    const struct cred *cred;
531    int ret;
532
533    rcu_read_lock();
534    cred = __task_cred(p);
535    ret = ((fown->euid == 0 ||
536        fown->euid == cred->suid || fown->euid == cred->uid ||
537        fown->uid == cred->suid || fown->uid == cred->uid) &&
538           !security_file_send_sigiotask(p, fown, sig));
539    rcu_read_unlock();
540    return ret;
541}
542
543static void send_sigio_to_task(struct task_struct *p,
544                   struct fown_struct *fown,
545                   int fd, int reason, int group)
546{
547    /*
548     * F_SETSIG can change ->signum lockless in parallel, make
549     * sure we read it once and use the same value throughout.
550     */
551    int signum = ACCESS_ONCE(fown->signum);
552
553    if (!sigio_perm(p, fown, signum))
554        return;
555
556    switch (signum) {
557        siginfo_t si;
558        default:
559            /* Queue a rt signal with the appropriate fd as its
560               value. We use SI_SIGIO as the source, not
561               SI_KERNEL, since kernel signals always get
562               delivered even if we can't queue. Failure to
563               queue in this case _should_ be reported; we fall
564               back to SIGIO in that case. --sct */
565            si.si_signo = signum;
566            si.si_errno = 0;
567                si.si_code = reason;
568            /* Make sure we are called with one of the POLL_*
569               reasons, otherwise we could leak kernel stack into
570               userspace. */
571            BUG_ON((reason & __SI_MASK) != __SI_POLL);
572            if (reason - POLL_IN >= NSIGPOLL)
573                si.si_band = ~0L;
574            else
575                si.si_band = band_table[reason - POLL_IN];
576            si.si_fd = fd;
577            if (!do_send_sig_info(signum, &si, p, group))
578                break;
579        /* fall-through: fall back on the old plain SIGIO signal */
580        case 0:
581            do_send_sig_info(SIGIO, SEND_SIG_PRIV, p, group);
582    }
583}
584
585void send_sigio(struct fown_struct *fown, int fd, int band)
586{
587    struct task_struct *p;
588    enum pid_type type;
589    struct pid *pid;
590    int group = 1;
591    
592    read_lock(&fown->lock);
593
594    type = fown->pid_type;
595    if (type == PIDTYPE_MAX) {
596        group = 0;
597        type = PIDTYPE_PID;
598    }
599
600    pid = fown->pid;
601    if (!pid)
602        goto out_unlock_fown;
603    
604    read_lock(&tasklist_lock);
605    do_each_pid_task(pid, type, p) {
606        send_sigio_to_task(p, fown, fd, band, group);
607    } while_each_pid_task(pid, type, p);
608    read_unlock(&tasklist_lock);
609 out_unlock_fown:
610    read_unlock(&fown->lock);
611}
612
613static void send_sigurg_to_task(struct task_struct *p,
614                struct fown_struct *fown, int group)
615{
616    if (sigio_perm(p, fown, SIGURG))
617        do_send_sig_info(SIGURG, SEND_SIG_PRIV, p, group);
618}
619
620int send_sigurg(struct fown_struct *fown)
621{
622    struct task_struct *p;
623    enum pid_type type;
624    struct pid *pid;
625    int group = 1;
626    int ret = 0;
627    
628    read_lock(&fown->lock);
629
630    type = fown->pid_type;
631    if (type == PIDTYPE_MAX) {
632        group = 0;
633        type = PIDTYPE_PID;
634    }
635
636    pid = fown->pid;
637    if (!pid)
638        goto out_unlock_fown;
639
640    ret = 1;
641    
642    read_lock(&tasklist_lock);
643    do_each_pid_task(pid, type, p) {
644        send_sigurg_to_task(p, fown, group);
645    } while_each_pid_task(pid, type, p);
646    read_unlock(&tasklist_lock);
647 out_unlock_fown:
648    read_unlock(&fown->lock);
649    return ret;
650}
651
652static DEFINE_SPINLOCK(fasync_lock);
653static struct kmem_cache *fasync_cache __read_mostly;
654
655static void fasync_free_rcu(struct rcu_head *head)
656{
657    kmem_cache_free(fasync_cache,
658            container_of(head, struct fasync_struct, fa_rcu));
659}
660
661/*
662 * Remove a fasync entry. If successfully removed, return
663 * positive and clear the FASYNC flag. If no entry exists,
664 * do nothing and return 0.
665 *
666 * NOTE! It is very important that the FASYNC flag always
667 * match the state "is the filp on a fasync list".
668 *
669 */
670int fasync_remove_entry(struct file *filp, struct fasync_struct **fapp)
671{
672    struct fasync_struct *fa, **fp;
673    int result = 0;
674
675    spin_lock(&filp->f_lock);
676    spin_lock(&fasync_lock);
677    for (fp = fapp; (fa = *fp) != NULL; fp = &fa->fa_next) {
678        if (fa->fa_file != filp)
679            continue;
680
681        spin_lock_irq(&fa->fa_lock);
682        fa->fa_file = NULL;
683        spin_unlock_irq(&fa->fa_lock);
684
685        *fp = fa->fa_next;
686        call_rcu(&fa->fa_rcu, fasync_free_rcu);
687        filp->f_flags &= ~FASYNC;
688        result = 1;
689        break;
690    }
691    spin_unlock(&fasync_lock);
692    spin_unlock(&filp->f_lock);
693    return result;
694}
695
696struct fasync_struct *fasync_alloc(void)
697{
698    return kmem_cache_alloc(fasync_cache, GFP_KERNEL);
699}
700
701/*
702 * NOTE! This can be used only for unused fasync entries:
703 * entries that actually got inserted on the fasync list
704 * need to be released by rcu - see fasync_remove_entry.
705 */
706void fasync_free(struct fasync_struct *new)
707{
708    kmem_cache_free(fasync_cache, new);
709}
710
711/*
712 * Insert a new entry into the fasync list. Return the pointer to the
713 * old one if we didn't use the new one.
714 *
715 * NOTE! It is very important that the FASYNC flag always
716 * match the state "is the filp on a fasync list".
717 */
718struct fasync_struct *fasync_insert_entry(int fd, struct file *filp, struct fasync_struct **fapp, struct fasync_struct *new)
719{
720        struct fasync_struct *fa, **fp;
721
722    spin_lock(&filp->f_lock);
723    spin_lock(&fasync_lock);
724    for (fp = fapp; (fa = *fp) != NULL; fp = &fa->fa_next) {
725        if (fa->fa_file != filp)
726            continue;
727
728        spin_lock_irq(&fa->fa_lock);
729        fa->fa_fd = fd;
730        spin_unlock_irq(&fa->fa_lock);
731        goto out;
732    }
733
734    spin_lock_init(&new->fa_lock);
735    new->magic = FASYNC_MAGIC;
736    new->fa_file = filp;
737    new->fa_fd = fd;
738    new->fa_next = *fapp;
739    rcu_assign_pointer(*fapp, new);
740    filp->f_flags |= FASYNC;
741
742out:
743    spin_unlock(&fasync_lock);
744    spin_unlock(&filp->f_lock);
745    return fa;
746}
747
748/*
749 * Add a fasync entry. Return negative on error, positive if
750 * added, and zero if did nothing but change an existing one.
751 */
752static int fasync_add_entry(int fd, struct file *filp, struct fasync_struct **fapp)
753{
754    struct fasync_struct *new;
755
756    new = fasync_alloc();
757    if (!new)
758        return -ENOMEM;
759
760    /*
761     * fasync_insert_entry() returns the old (update) entry if
762     * it existed.
763     *
764     * So free the (unused) new entry and return 0 to let the
765     * caller know that we didn't add any new fasync entries.
766     */
767    if (fasync_insert_entry(fd, filp, fapp, new)) {
768        fasync_free(new);
769        return 0;
770    }
771
772    return 1;
773}
774
775/*
776 * fasync_helper() is used by almost all character device drivers
777 * to set up the fasync queue, and for regular files by the file
778 * lease code. It returns negative on error, 0 if it did no changes
779 * and positive if it added/deleted the entry.
780 */
781int fasync_helper(int fd, struct file * filp, int on, struct fasync_struct **fapp)
782{
783    if (!on)
784        return fasync_remove_entry(filp, fapp);
785    return fasync_add_entry(fd, filp, fapp);
786}
787
788EXPORT_SYMBOL(fasync_helper);
789
790/*
791 * rcu_read_lock() is held
792 */
793static void kill_fasync_rcu(struct fasync_struct *fa, int sig, int band)
794{
795    while (fa) {
796        struct fown_struct *fown;
797        unsigned long flags;
798
799        if (fa->magic != FASYNC_MAGIC) {
800            printk(KERN_ERR "kill_fasync: bad magic number in "
801                   "fasync_struct!\n");
802            return;
803        }
804        spin_lock_irqsave(&fa->fa_lock, flags);
805        if (fa->fa_file) {
806            fown = &fa->fa_file->f_owner;
807            /* Don't send SIGURG to processes which have not set a
808               queued signum: SIGURG has its own default signalling
809               mechanism. */
810            if (!(sig == SIGURG && fown->signum == 0))
811                send_sigio(fown, fa->fa_fd, band);
812        }
813        spin_unlock_irqrestore(&fa->fa_lock, flags);
814        fa = rcu_dereference(fa->fa_next);
815    }
816}
817
818void kill_fasync(struct fasync_struct **fp, int sig, int band)
819{
820    /* First a quick test without locking: usually
821     * the list is empty.
822     */
823    if (*fp) {
824        rcu_read_lock();
825        kill_fasync_rcu(rcu_dereference(*fp), sig, band);
826        rcu_read_unlock();
827    }
828}
829EXPORT_SYMBOL(kill_fasync);
830
831static int __init fcntl_init(void)
832{
833    /*
834     * Please add new bits here to ensure allocation uniqueness.
835     * Exceptions: O_NONBLOCK is a two bit define on parisc; O_NDELAY
836     * is defined as O_NONBLOCK on some platforms and not on others.
837     */
838    BUILD_BUG_ON(19 - 1 /* for O_RDONLY being 0 */ != HWEIGHT32(
839        O_RDONLY | O_WRONLY | O_RDWR |
840        O_CREAT | O_EXCL | O_NOCTTY |
841        O_TRUNC | O_APPEND | /* O_NONBLOCK | */
842        __O_SYNC | O_DSYNC | FASYNC |
843        O_DIRECT | O_LARGEFILE | O_DIRECTORY |
844        O_NOFOLLOW | O_NOATIME | O_CLOEXEC |
845        __FMODE_EXEC | O_PATH
846        ));
847
848    fasync_cache = kmem_cache_create("fasync_cache",
849        sizeof(struct fasync_struct), 0, SLAB_PANIC, NULL);
850    return 0;
851}
852
853module_init(fcntl_init)
854

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