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Source at commit b386be689295730688885552666ea40b2e639b14 created 11 years 11 months ago. By Maarten ter Huurne, Revert "MIPS: JZ4740: reset: Initialize hibernate wakeup counters." | |
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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 | |
28 | void 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 | |
41 | static 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 | |
53 | SYSCALL_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 | |
109 | Ebadf: |
110 | err = -EBADF; |
111 | out_unlock: |
112 | spin_unlock(&files->file_lock); |
113 | return err; |
114 | } |
115 | |
116 | SYSCALL_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 | |
131 | SYSCALL_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 | |
148 | static 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 | |
200 | static 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 | |
218 | int __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 | } |
230 | EXPORT_SYMBOL(__f_setown); |
231 | |
232 | int 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 | } |
249 | EXPORT_SYMBOL(f_setown); |
250 | |
251 | void f_delown(struct file *filp) |
252 | { |
253 | f_modown(filp, NULL, PIDTYPE_PID, 1); |
254 | } |
255 | |
256 | pid_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 | |
267 | static 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 | |
307 | static 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 | |
343 | static 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 | |
429 | static 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 | |
442 | SYSCALL_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); |
467 | out: |
468 | return err; |
469 | } |
470 | |
471 | #if BITS_PER_LONG == 32 |
472 | SYSCALL_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); |
511 | out: |
512 | return err; |
513 | } |
514 | #endif |
515 | |
516 | /* Table to convert sigio signal codes into poll band bitmaps */ |
517 | |
518 | static 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 | |
527 | static 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 | |
543 | static 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 | |
585 | void 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 | |
613 | static 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 | |
620 | int 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 | |
652 | static DEFINE_SPINLOCK(fasync_lock); |
653 | static struct kmem_cache *fasync_cache __read_mostly; |
654 | |
655 | static 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 | */ |
670 | int 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 | |
696 | struct 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 | */ |
706 | void 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 | */ |
718 | struct 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 | |
742 | out: |
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 | */ |
752 | static 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 | */ |
781 | int 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 | |
788 | EXPORT_SYMBOL(fasync_helper); |
789 | |
790 | /* |
791 | * rcu_read_lock() is held |
792 | */ |
793 | static 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 | |
818 | void 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 | } |
829 | EXPORT_SYMBOL(kill_fasync); |
830 | |
831 | static 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 | |
853 | module_init(fcntl_init) |
854 |
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