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1 | /* |
2 | * linux/fs/pipe.c |
3 | * |
4 | * Copyright (C) 1991, 1992, 1999 Linus Torvalds |
5 | */ |
6 | |
7 | #include <linux/mm.h> |
8 | #include <linux/file.h> |
9 | #include <linux/poll.h> |
10 | #include <linux/slab.h> |
11 | #include <linux/module.h> |
12 | #include <linux/init.h> |
13 | #include <linux/fs.h> |
14 | #include <linux/log2.h> |
15 | #include <linux/mount.h> |
16 | #include <linux/magic.h> |
17 | #include <linux/pipe_fs_i.h> |
18 | #include <linux/uio.h> |
19 | #include <linux/highmem.h> |
20 | #include <linux/pagemap.h> |
21 | #include <linux/audit.h> |
22 | #include <linux/syscalls.h> |
23 | #include <linux/fcntl.h> |
24 | |
25 | #include <asm/uaccess.h> |
26 | #include <asm/ioctls.h> |
27 | |
28 | /* |
29 | * The max size that a non-root user is allowed to grow the pipe. Can |
30 | * be set by root in /proc/sys/fs/pipe-max-size |
31 | */ |
32 | unsigned int pipe_max_size = 1048576; |
33 | |
34 | /* |
35 | * Minimum pipe size, as required by POSIX |
36 | */ |
37 | unsigned int pipe_min_size = PAGE_SIZE; |
38 | |
39 | /* |
40 | * We use a start+len construction, which provides full use of the |
41 | * allocated memory. |
42 | * -- Florian Coosmann (FGC) |
43 | * |
44 | * Reads with count = 0 should always return 0. |
45 | * -- Julian Bradfield 1999-06-07. |
46 | * |
47 | * FIFOs and Pipes now generate SIGIO for both readers and writers. |
48 | * -- Jeremy Elson <jelson@circlemud.org> 2001-08-16 |
49 | * |
50 | * pipe_read & write cleanup |
51 | * -- Manfred Spraul <manfred@colorfullife.com> 2002-05-09 |
52 | */ |
53 | |
54 | static void pipe_lock_nested(struct pipe_inode_info *pipe, int subclass) |
55 | { |
56 | if (pipe->inode) |
57 | mutex_lock_nested(&pipe->inode->i_mutex, subclass); |
58 | } |
59 | |
60 | void pipe_lock(struct pipe_inode_info *pipe) |
61 | { |
62 | /* |
63 | * pipe_lock() nests non-pipe inode locks (for writing to a file) |
64 | */ |
65 | pipe_lock_nested(pipe, I_MUTEX_PARENT); |
66 | } |
67 | EXPORT_SYMBOL(pipe_lock); |
68 | |
69 | void pipe_unlock(struct pipe_inode_info *pipe) |
70 | { |
71 | if (pipe->inode) |
72 | mutex_unlock(&pipe->inode->i_mutex); |
73 | } |
74 | EXPORT_SYMBOL(pipe_unlock); |
75 | |
76 | void pipe_double_lock(struct pipe_inode_info *pipe1, |
77 | struct pipe_inode_info *pipe2) |
78 | { |
79 | BUG_ON(pipe1 == pipe2); |
80 | |
81 | if (pipe1 < pipe2) { |
82 | pipe_lock_nested(pipe1, I_MUTEX_PARENT); |
83 | pipe_lock_nested(pipe2, I_MUTEX_CHILD); |
84 | } else { |
85 | pipe_lock_nested(pipe2, I_MUTEX_PARENT); |
86 | pipe_lock_nested(pipe1, I_MUTEX_CHILD); |
87 | } |
88 | } |
89 | |
90 | /* Drop the inode semaphore and wait for a pipe event, atomically */ |
91 | void pipe_wait(struct pipe_inode_info *pipe) |
92 | { |
93 | DEFINE_WAIT(wait); |
94 | |
95 | /* |
96 | * Pipes are system-local resources, so sleeping on them |
97 | * is considered a noninteractive wait: |
98 | */ |
99 | prepare_to_wait(&pipe->wait, &wait, TASK_INTERRUPTIBLE); |
100 | pipe_unlock(pipe); |
101 | schedule(); |
102 | finish_wait(&pipe->wait, &wait); |
103 | pipe_lock(pipe); |
104 | } |
105 | |
106 | static int |
107 | pipe_iov_copy_from_user(void *to, struct iovec *iov, unsigned long len, |
108 | int atomic) |
109 | { |
110 | unsigned long copy; |
111 | |
112 | while (len > 0) { |
113 | while (!iov->iov_len) |
114 | iov++; |
115 | copy = min_t(unsigned long, len, iov->iov_len); |
116 | |
117 | if (atomic) { |
118 | if (__copy_from_user_inatomic(to, iov->iov_base, copy)) |
119 | return -EFAULT; |
120 | } else { |
121 | if (copy_from_user(to, iov->iov_base, copy)) |
122 | return -EFAULT; |
123 | } |
124 | to += copy; |
125 | len -= copy; |
126 | iov->iov_base += copy; |
127 | iov->iov_len -= copy; |
128 | } |
129 | return 0; |
130 | } |
131 | |
132 | static int |
133 | pipe_iov_copy_to_user(struct iovec *iov, const void *from, unsigned long len, |
134 | int atomic) |
135 | { |
136 | unsigned long copy; |
137 | |
138 | while (len > 0) { |
139 | while (!iov->iov_len) |
140 | iov++; |
141 | copy = min_t(unsigned long, len, iov->iov_len); |
142 | |
143 | if (atomic) { |
144 | if (__copy_to_user_inatomic(iov->iov_base, from, copy)) |
145 | return -EFAULT; |
146 | } else { |
147 | if (copy_to_user(iov->iov_base, from, copy)) |
148 | return -EFAULT; |
149 | } |
150 | from += copy; |
151 | len -= copy; |
152 | iov->iov_base += copy; |
153 | iov->iov_len -= copy; |
154 | } |
155 | return 0; |
156 | } |
157 | |
158 | /* |
159 | * Attempt to pre-fault in the user memory, so we can use atomic copies. |
160 | * Returns the number of bytes not faulted in. |
161 | */ |
162 | static int iov_fault_in_pages_write(struct iovec *iov, unsigned long len) |
163 | { |
164 | while (!iov->iov_len) |
165 | iov++; |
166 | |
167 | while (len > 0) { |
168 | unsigned long this_len; |
169 | |
170 | this_len = min_t(unsigned long, len, iov->iov_len); |
171 | if (fault_in_pages_writeable(iov->iov_base, this_len)) |
172 | break; |
173 | |
174 | len -= this_len; |
175 | iov++; |
176 | } |
177 | |
178 | return len; |
179 | } |
180 | |
181 | /* |
182 | * Pre-fault in the user memory, so we can use atomic copies. |
183 | */ |
184 | static void iov_fault_in_pages_read(struct iovec *iov, unsigned long len) |
185 | { |
186 | while (!iov->iov_len) |
187 | iov++; |
188 | |
189 | while (len > 0) { |
190 | unsigned long this_len; |
191 | |
192 | this_len = min_t(unsigned long, len, iov->iov_len); |
193 | fault_in_pages_readable(iov->iov_base, this_len); |
194 | len -= this_len; |
195 | iov++; |
196 | } |
197 | } |
198 | |
199 | static void anon_pipe_buf_release(struct pipe_inode_info *pipe, |
200 | struct pipe_buffer *buf) |
201 | { |
202 | struct page *page = buf->page; |
203 | |
204 | /* |
205 | * If nobody else uses this page, and we don't already have a |
206 | * temporary page, let's keep track of it as a one-deep |
207 | * allocation cache. (Otherwise just release our reference to it) |
208 | */ |
209 | if (page_count(page) == 1 && !pipe->tmp_page) |
210 | pipe->tmp_page = page; |
211 | else |
212 | page_cache_release(page); |
213 | } |
214 | |
215 | /** |
216 | * generic_pipe_buf_map - virtually map a pipe buffer |
217 | * @pipe: the pipe that the buffer belongs to |
218 | * @buf: the buffer that should be mapped |
219 | * @atomic: whether to use an atomic map |
220 | * |
221 | * Description: |
222 | * This function returns a kernel virtual address mapping for the |
223 | * pipe_buffer passed in @buf. If @atomic is set, an atomic map is provided |
224 | * and the caller has to be careful not to fault before calling |
225 | * the unmap function. |
226 | * |
227 | * Note that this function calls kmap_atomic() if @atomic != 0. |
228 | */ |
229 | void *generic_pipe_buf_map(struct pipe_inode_info *pipe, |
230 | struct pipe_buffer *buf, int atomic) |
231 | { |
232 | if (atomic) { |
233 | buf->flags |= PIPE_BUF_FLAG_ATOMIC; |
234 | return kmap_atomic(buf->page); |
235 | } |
236 | |
237 | return kmap(buf->page); |
238 | } |
239 | EXPORT_SYMBOL(generic_pipe_buf_map); |
240 | |
241 | /** |
242 | * generic_pipe_buf_unmap - unmap a previously mapped pipe buffer |
243 | * @pipe: the pipe that the buffer belongs to |
244 | * @buf: the buffer that should be unmapped |
245 | * @map_data: the data that the mapping function returned |
246 | * |
247 | * Description: |
248 | * This function undoes the mapping that ->map() provided. |
249 | */ |
250 | void generic_pipe_buf_unmap(struct pipe_inode_info *pipe, |
251 | struct pipe_buffer *buf, void *map_data) |
252 | { |
253 | if (buf->flags & PIPE_BUF_FLAG_ATOMIC) { |
254 | buf->flags &= ~PIPE_BUF_FLAG_ATOMIC; |
255 | kunmap_atomic(map_data); |
256 | } else |
257 | kunmap(buf->page); |
258 | } |
259 | EXPORT_SYMBOL(generic_pipe_buf_unmap); |
260 | |
261 | /** |
262 | * generic_pipe_buf_steal - attempt to take ownership of a &pipe_buffer |
263 | * @pipe: the pipe that the buffer belongs to |
264 | * @buf: the buffer to attempt to steal |
265 | * |
266 | * Description: |
267 | * This function attempts to steal the &struct page attached to |
268 | * @buf. If successful, this function returns 0 and returns with |
269 | * the page locked. The caller may then reuse the page for whatever |
270 | * he wishes; the typical use is insertion into a different file |
271 | * page cache. |
272 | */ |
273 | int generic_pipe_buf_steal(struct pipe_inode_info *pipe, |
274 | struct pipe_buffer *buf) |
275 | { |
276 | struct page *page = buf->page; |
277 | |
278 | /* |
279 | * A reference of one is golden, that means that the owner of this |
280 | * page is the only one holding a reference to it. lock the page |
281 | * and return OK. |
282 | */ |
283 | if (page_count(page) == 1) { |
284 | lock_page(page); |
285 | return 0; |
286 | } |
287 | |
288 | return 1; |
289 | } |
290 | EXPORT_SYMBOL(generic_pipe_buf_steal); |
291 | |
292 | /** |
293 | * generic_pipe_buf_get - get a reference to a &struct pipe_buffer |
294 | * @pipe: the pipe that the buffer belongs to |
295 | * @buf: the buffer to get a reference to |
296 | * |
297 | * Description: |
298 | * This function grabs an extra reference to @buf. It's used in |
299 | * in the tee() system call, when we duplicate the buffers in one |
300 | * pipe into another. |
301 | */ |
302 | void generic_pipe_buf_get(struct pipe_inode_info *pipe, struct pipe_buffer *buf) |
303 | { |
304 | page_cache_get(buf->page); |
305 | } |
306 | EXPORT_SYMBOL(generic_pipe_buf_get); |
307 | |
308 | /** |
309 | * generic_pipe_buf_confirm - verify contents of the pipe buffer |
310 | * @info: the pipe that the buffer belongs to |
311 | * @buf: the buffer to confirm |
312 | * |
313 | * Description: |
314 | * This function does nothing, because the generic pipe code uses |
315 | * pages that are always good when inserted into the pipe. |
316 | */ |
317 | int generic_pipe_buf_confirm(struct pipe_inode_info *info, |
318 | struct pipe_buffer *buf) |
319 | { |
320 | return 0; |
321 | } |
322 | EXPORT_SYMBOL(generic_pipe_buf_confirm); |
323 | |
324 | /** |
325 | * generic_pipe_buf_release - put a reference to a &struct pipe_buffer |
326 | * @pipe: the pipe that the buffer belongs to |
327 | * @buf: the buffer to put a reference to |
328 | * |
329 | * Description: |
330 | * This function releases a reference to @buf. |
331 | */ |
332 | void generic_pipe_buf_release(struct pipe_inode_info *pipe, |
333 | struct pipe_buffer *buf) |
334 | { |
335 | page_cache_release(buf->page); |
336 | } |
337 | EXPORT_SYMBOL(generic_pipe_buf_release); |
338 | |
339 | static const struct pipe_buf_operations anon_pipe_buf_ops = { |
340 | .can_merge = 1, |
341 | .map = generic_pipe_buf_map, |
342 | .unmap = generic_pipe_buf_unmap, |
343 | .confirm = generic_pipe_buf_confirm, |
344 | .release = anon_pipe_buf_release, |
345 | .steal = generic_pipe_buf_steal, |
346 | .get = generic_pipe_buf_get, |
347 | }; |
348 | |
349 | static const struct pipe_buf_operations packet_pipe_buf_ops = { |
350 | .can_merge = 0, |
351 | .map = generic_pipe_buf_map, |
352 | .unmap = generic_pipe_buf_unmap, |
353 | .confirm = generic_pipe_buf_confirm, |
354 | .release = anon_pipe_buf_release, |
355 | .steal = generic_pipe_buf_steal, |
356 | .get = generic_pipe_buf_get, |
357 | }; |
358 | |
359 | static ssize_t |
360 | pipe_read(struct kiocb *iocb, const struct iovec *_iov, |
361 | unsigned long nr_segs, loff_t pos) |
362 | { |
363 | struct file *filp = iocb->ki_filp; |
364 | struct inode *inode = filp->f_path.dentry->d_inode; |
365 | struct pipe_inode_info *pipe; |
366 | int do_wakeup; |
367 | ssize_t ret; |
368 | struct iovec *iov = (struct iovec *)_iov; |
369 | size_t total_len; |
370 | |
371 | total_len = iov_length(iov, nr_segs); |
372 | /* Null read succeeds. */ |
373 | if (unlikely(total_len == 0)) |
374 | return 0; |
375 | |
376 | do_wakeup = 0; |
377 | ret = 0; |
378 | mutex_lock(&inode->i_mutex); |
379 | pipe = inode->i_pipe; |
380 | for (;;) { |
381 | int bufs = pipe->nrbufs; |
382 | if (bufs) { |
383 | int curbuf = pipe->curbuf; |
384 | struct pipe_buffer *buf = pipe->bufs + curbuf; |
385 | const struct pipe_buf_operations *ops = buf->ops; |
386 | void *addr; |
387 | size_t chars = buf->len; |
388 | int error, atomic; |
389 | |
390 | if (chars > total_len) |
391 | chars = total_len; |
392 | |
393 | error = ops->confirm(pipe, buf); |
394 | if (error) { |
395 | if (!ret) |
396 | ret = error; |
397 | break; |
398 | } |
399 | |
400 | atomic = !iov_fault_in_pages_write(iov, chars); |
401 | redo: |
402 | addr = ops->map(pipe, buf, atomic); |
403 | error = pipe_iov_copy_to_user(iov, addr + buf->offset, chars, atomic); |
404 | ops->unmap(pipe, buf, addr); |
405 | if (unlikely(error)) { |
406 | /* |
407 | * Just retry with the slow path if we failed. |
408 | */ |
409 | if (atomic) { |
410 | atomic = 0; |
411 | goto redo; |
412 | } |
413 | if (!ret) |
414 | ret = error; |
415 | break; |
416 | } |
417 | ret += chars; |
418 | buf->offset += chars; |
419 | buf->len -= chars; |
420 | |
421 | /* Was it a packet buffer? Clean up and exit */ |
422 | if (buf->flags & PIPE_BUF_FLAG_PACKET) { |
423 | total_len = chars; |
424 | buf->len = 0; |
425 | } |
426 | |
427 | if (!buf->len) { |
428 | buf->ops = NULL; |
429 | ops->release(pipe, buf); |
430 | curbuf = (curbuf + 1) & (pipe->buffers - 1); |
431 | pipe->curbuf = curbuf; |
432 | pipe->nrbufs = --bufs; |
433 | do_wakeup = 1; |
434 | } |
435 | total_len -= chars; |
436 | if (!total_len) |
437 | break; /* common path: read succeeded */ |
438 | } |
439 | if (bufs) /* More to do? */ |
440 | continue; |
441 | if (!pipe->writers) |
442 | break; |
443 | if (!pipe->waiting_writers) { |
444 | /* syscall merging: Usually we must not sleep |
445 | * if O_NONBLOCK is set, or if we got some data. |
446 | * But if a writer sleeps in kernel space, then |
447 | * we can wait for that data without violating POSIX. |
448 | */ |
449 | if (ret) |
450 | break; |
451 | if (filp->f_flags & O_NONBLOCK) { |
452 | ret = -EAGAIN; |
453 | break; |
454 | } |
455 | } |
456 | if (signal_pending(current)) { |
457 | if (!ret) |
458 | ret = -ERESTARTSYS; |
459 | break; |
460 | } |
461 | if (do_wakeup) { |
462 | wake_up_interruptible_sync_poll(&pipe->wait, POLLOUT | POLLWRNORM); |
463 | kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT); |
464 | } |
465 | pipe_wait(pipe); |
466 | } |
467 | mutex_unlock(&inode->i_mutex); |
468 | |
469 | /* Signal writers asynchronously that there is more room. */ |
470 | if (do_wakeup) { |
471 | wake_up_interruptible_sync_poll(&pipe->wait, POLLOUT | POLLWRNORM); |
472 | kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT); |
473 | } |
474 | if (ret > 0) |
475 | file_accessed(filp); |
476 | return ret; |
477 | } |
478 | |
479 | static inline int is_packetized(struct file *file) |
480 | { |
481 | return (file->f_flags & O_DIRECT) != 0; |
482 | } |
483 | |
484 | static ssize_t |
485 | pipe_write(struct kiocb *iocb, const struct iovec *_iov, |
486 | unsigned long nr_segs, loff_t ppos) |
487 | { |
488 | struct file *filp = iocb->ki_filp; |
489 | struct inode *inode = filp->f_path.dentry->d_inode; |
490 | struct pipe_inode_info *pipe; |
491 | ssize_t ret; |
492 | int do_wakeup; |
493 | struct iovec *iov = (struct iovec *)_iov; |
494 | size_t total_len; |
495 | ssize_t chars; |
496 | |
497 | total_len = iov_length(iov, nr_segs); |
498 | /* Null write succeeds. */ |
499 | if (unlikely(total_len == 0)) |
500 | return 0; |
501 | |
502 | do_wakeup = 0; |
503 | ret = 0; |
504 | mutex_lock(&inode->i_mutex); |
505 | pipe = inode->i_pipe; |
506 | |
507 | if (!pipe->readers) { |
508 | send_sig(SIGPIPE, current, 0); |
509 | ret = -EPIPE; |
510 | goto out; |
511 | } |
512 | |
513 | /* We try to merge small writes */ |
514 | chars = total_len & (PAGE_SIZE-1); /* size of the last buffer */ |
515 | if (pipe->nrbufs && chars != 0) { |
516 | int lastbuf = (pipe->curbuf + pipe->nrbufs - 1) & |
517 | (pipe->buffers - 1); |
518 | struct pipe_buffer *buf = pipe->bufs + lastbuf; |
519 | const struct pipe_buf_operations *ops = buf->ops; |
520 | int offset = buf->offset + buf->len; |
521 | |
522 | if (ops->can_merge && offset + chars <= PAGE_SIZE) { |
523 | int error, atomic = 1; |
524 | void *addr; |
525 | |
526 | error = ops->confirm(pipe, buf); |
527 | if (error) |
528 | goto out; |
529 | |
530 | iov_fault_in_pages_read(iov, chars); |
531 | redo1: |
532 | addr = ops->map(pipe, buf, atomic); |
533 | error = pipe_iov_copy_from_user(offset + addr, iov, |
534 | chars, atomic); |
535 | ops->unmap(pipe, buf, addr); |
536 | ret = error; |
537 | do_wakeup = 1; |
538 | if (error) { |
539 | if (atomic) { |
540 | atomic = 0; |
541 | goto redo1; |
542 | } |
543 | goto out; |
544 | } |
545 | buf->len += chars; |
546 | total_len -= chars; |
547 | ret = chars; |
548 | if (!total_len) |
549 | goto out; |
550 | } |
551 | } |
552 | |
553 | for (;;) { |
554 | int bufs; |
555 | |
556 | if (!pipe->readers) { |
557 | send_sig(SIGPIPE, current, 0); |
558 | if (!ret) |
559 | ret = -EPIPE; |
560 | break; |
561 | } |
562 | bufs = pipe->nrbufs; |
563 | if (bufs < pipe->buffers) { |
564 | int newbuf = (pipe->curbuf + bufs) & (pipe->buffers-1); |
565 | struct pipe_buffer *buf = pipe->bufs + newbuf; |
566 | struct page *page = pipe->tmp_page; |
567 | char *src; |
568 | int error, atomic = 1; |
569 | |
570 | if (!page) { |
571 | page = alloc_page(GFP_HIGHUSER); |
572 | if (unlikely(!page)) { |
573 | ret = ret ? : -ENOMEM; |
574 | break; |
575 | } |
576 | pipe->tmp_page = page; |
577 | } |
578 | /* Always wake up, even if the copy fails. Otherwise |
579 | * we lock up (O_NONBLOCK-)readers that sleep due to |
580 | * syscall merging. |
581 | * FIXME! Is this really true? |
582 | */ |
583 | do_wakeup = 1; |
584 | chars = PAGE_SIZE; |
585 | if (chars > total_len) |
586 | chars = total_len; |
587 | |
588 | iov_fault_in_pages_read(iov, chars); |
589 | redo2: |
590 | if (atomic) |
591 | src = kmap_atomic(page); |
592 | else |
593 | src = kmap(page); |
594 | |
595 | error = pipe_iov_copy_from_user(src, iov, chars, |
596 | atomic); |
597 | if (atomic) |
598 | kunmap_atomic(src); |
599 | else |
600 | kunmap(page); |
601 | |
602 | if (unlikely(error)) { |
603 | if (atomic) { |
604 | atomic = 0; |
605 | goto redo2; |
606 | } |
607 | if (!ret) |
608 | ret = error; |
609 | break; |
610 | } |
611 | ret += chars; |
612 | |
613 | /* Insert it into the buffer array */ |
614 | buf->page = page; |
615 | buf->ops = &anon_pipe_buf_ops; |
616 | buf->offset = 0; |
617 | buf->len = chars; |
618 | buf->flags = 0; |
619 | if (is_packetized(filp)) { |
620 | buf->ops = &packet_pipe_buf_ops; |
621 | buf->flags = PIPE_BUF_FLAG_PACKET; |
622 | } |
623 | pipe->nrbufs = ++bufs; |
624 | pipe->tmp_page = NULL; |
625 | |
626 | total_len -= chars; |
627 | if (!total_len) |
628 | break; |
629 | } |
630 | if (bufs < pipe->buffers) |
631 | continue; |
632 | if (filp->f_flags & O_NONBLOCK) { |
633 | if (!ret) |
634 | ret = -EAGAIN; |
635 | break; |
636 | } |
637 | if (signal_pending(current)) { |
638 | if (!ret) |
639 | ret = -ERESTARTSYS; |
640 | break; |
641 | } |
642 | if (do_wakeup) { |
643 | wake_up_interruptible_sync_poll(&pipe->wait, POLLIN | POLLRDNORM); |
644 | kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); |
645 | do_wakeup = 0; |
646 | } |
647 | pipe->waiting_writers++; |
648 | pipe_wait(pipe); |
649 | pipe->waiting_writers--; |
650 | } |
651 | out: |
652 | mutex_unlock(&inode->i_mutex); |
653 | if (do_wakeup) { |
654 | wake_up_interruptible_sync_poll(&pipe->wait, POLLIN | POLLRDNORM); |
655 | kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); |
656 | } |
657 | if (ret > 0) { |
658 | int err = file_update_time(filp); |
659 | if (err) |
660 | ret = err; |
661 | } |
662 | return ret; |
663 | } |
664 | |
665 | static ssize_t |
666 | bad_pipe_r(struct file *filp, char __user *buf, size_t count, loff_t *ppos) |
667 | { |
668 | return -EBADF; |
669 | } |
670 | |
671 | static ssize_t |
672 | bad_pipe_w(struct file *filp, const char __user *buf, size_t count, |
673 | loff_t *ppos) |
674 | { |
675 | return -EBADF; |
676 | } |
677 | |
678 | static long pipe_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) |
679 | { |
680 | struct inode *inode = filp->f_path.dentry->d_inode; |
681 | struct pipe_inode_info *pipe; |
682 | int count, buf, nrbufs; |
683 | |
684 | switch (cmd) { |
685 | case FIONREAD: |
686 | mutex_lock(&inode->i_mutex); |
687 | pipe = inode->i_pipe; |
688 | count = 0; |
689 | buf = pipe->curbuf; |
690 | nrbufs = pipe->nrbufs; |
691 | while (--nrbufs >= 0) { |
692 | count += pipe->bufs[buf].len; |
693 | buf = (buf+1) & (pipe->buffers - 1); |
694 | } |
695 | mutex_unlock(&inode->i_mutex); |
696 | |
697 | return put_user(count, (int __user *)arg); |
698 | default: |
699 | return -ENOIOCTLCMD; |
700 | } |
701 | } |
702 | |
703 | /* No kernel lock held - fine */ |
704 | static unsigned int |
705 | pipe_poll(struct file *filp, poll_table *wait) |
706 | { |
707 | unsigned int mask; |
708 | struct inode *inode = filp->f_path.dentry->d_inode; |
709 | struct pipe_inode_info *pipe = inode->i_pipe; |
710 | int nrbufs; |
711 | |
712 | poll_wait(filp, &pipe->wait, wait); |
713 | |
714 | /* Reading only -- no need for acquiring the semaphore. */ |
715 | nrbufs = pipe->nrbufs; |
716 | mask = 0; |
717 | if (filp->f_mode & FMODE_READ) { |
718 | mask = (nrbufs > 0) ? POLLIN | POLLRDNORM : 0; |
719 | if (!pipe->writers && filp->f_version != pipe->w_counter) |
720 | mask |= POLLHUP; |
721 | } |
722 | |
723 | if (filp->f_mode & FMODE_WRITE) { |
724 | mask |= (nrbufs < pipe->buffers) ? POLLOUT | POLLWRNORM : 0; |
725 | /* |
726 | * Most Unices do not set POLLERR for FIFOs but on Linux they |
727 | * behave exactly like pipes for poll(). |
728 | */ |
729 | if (!pipe->readers) |
730 | mask |= POLLERR; |
731 | } |
732 | |
733 | return mask; |
734 | } |
735 | |
736 | static int |
737 | pipe_release(struct inode *inode, int decr, int decw) |
738 | { |
739 | struct pipe_inode_info *pipe; |
740 | |
741 | mutex_lock(&inode->i_mutex); |
742 | pipe = inode->i_pipe; |
743 | pipe->readers -= decr; |
744 | pipe->writers -= decw; |
745 | |
746 | if (!pipe->readers && !pipe->writers) { |
747 | free_pipe_info(inode); |
748 | } else { |
749 | wake_up_interruptible_sync_poll(&pipe->wait, POLLIN | POLLOUT | POLLRDNORM | POLLWRNORM | POLLERR | POLLHUP); |
750 | kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); |
751 | kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT); |
752 | } |
753 | mutex_unlock(&inode->i_mutex); |
754 | |
755 | return 0; |
756 | } |
757 | |
758 | static int |
759 | pipe_read_fasync(int fd, struct file *filp, int on) |
760 | { |
761 | struct inode *inode = filp->f_path.dentry->d_inode; |
762 | int retval; |
763 | |
764 | mutex_lock(&inode->i_mutex); |
765 | retval = fasync_helper(fd, filp, on, &inode->i_pipe->fasync_readers); |
766 | mutex_unlock(&inode->i_mutex); |
767 | |
768 | return retval; |
769 | } |
770 | |
771 | |
772 | static int |
773 | pipe_write_fasync(int fd, struct file *filp, int on) |
774 | { |
775 | struct inode *inode = filp->f_path.dentry->d_inode; |
776 | int retval; |
777 | |
778 | mutex_lock(&inode->i_mutex); |
779 | retval = fasync_helper(fd, filp, on, &inode->i_pipe->fasync_writers); |
780 | mutex_unlock(&inode->i_mutex); |
781 | |
782 | return retval; |
783 | } |
784 | |
785 | |
786 | static int |
787 | pipe_rdwr_fasync(int fd, struct file *filp, int on) |
788 | { |
789 | struct inode *inode = filp->f_path.dentry->d_inode; |
790 | struct pipe_inode_info *pipe = inode->i_pipe; |
791 | int retval; |
792 | |
793 | mutex_lock(&inode->i_mutex); |
794 | retval = fasync_helper(fd, filp, on, &pipe->fasync_readers); |
795 | if (retval >= 0) { |
796 | retval = fasync_helper(fd, filp, on, &pipe->fasync_writers); |
797 | if (retval < 0) /* this can happen only if on == T */ |
798 | fasync_helper(-1, filp, 0, &pipe->fasync_readers); |
799 | } |
800 | mutex_unlock(&inode->i_mutex); |
801 | return retval; |
802 | } |
803 | |
804 | |
805 | static int |
806 | pipe_read_release(struct inode *inode, struct file *filp) |
807 | { |
808 | return pipe_release(inode, 1, 0); |
809 | } |
810 | |
811 | static int |
812 | pipe_write_release(struct inode *inode, struct file *filp) |
813 | { |
814 | return pipe_release(inode, 0, 1); |
815 | } |
816 | |
817 | static int |
818 | pipe_rdwr_release(struct inode *inode, struct file *filp) |
819 | { |
820 | int decr, decw; |
821 | |
822 | decr = (filp->f_mode & FMODE_READ) != 0; |
823 | decw = (filp->f_mode & FMODE_WRITE) != 0; |
824 | return pipe_release(inode, decr, decw); |
825 | } |
826 | |
827 | static int |
828 | pipe_read_open(struct inode *inode, struct file *filp) |
829 | { |
830 | int ret = -ENOENT; |
831 | |
832 | mutex_lock(&inode->i_mutex); |
833 | |
834 | if (inode->i_pipe) { |
835 | ret = 0; |
836 | inode->i_pipe->readers++; |
837 | } |
838 | |
839 | mutex_unlock(&inode->i_mutex); |
840 | |
841 | return ret; |
842 | } |
843 | |
844 | static int |
845 | pipe_write_open(struct inode *inode, struct file *filp) |
846 | { |
847 | int ret = -ENOENT; |
848 | |
849 | mutex_lock(&inode->i_mutex); |
850 | |
851 | if (inode->i_pipe) { |
852 | ret = 0; |
853 | inode->i_pipe->writers++; |
854 | } |
855 | |
856 | mutex_unlock(&inode->i_mutex); |
857 | |
858 | return ret; |
859 | } |
860 | |
861 | static int |
862 | pipe_rdwr_open(struct inode *inode, struct file *filp) |
863 | { |
864 | int ret = -ENOENT; |
865 | |
866 | mutex_lock(&inode->i_mutex); |
867 | |
868 | if (inode->i_pipe) { |
869 | ret = 0; |
870 | if (filp->f_mode & FMODE_READ) |
871 | inode->i_pipe->readers++; |
872 | if (filp->f_mode & FMODE_WRITE) |
873 | inode->i_pipe->writers++; |
874 | } |
875 | |
876 | mutex_unlock(&inode->i_mutex); |
877 | |
878 | return ret; |
879 | } |
880 | |
881 | /* |
882 | * The file_operations structs are not static because they |
883 | * are also used in linux/fs/fifo.c to do operations on FIFOs. |
884 | * |
885 | * Pipes reuse fifos' file_operations structs. |
886 | */ |
887 | const struct file_operations read_pipefifo_fops = { |
888 | .llseek = no_llseek, |
889 | .read = do_sync_read, |
890 | .aio_read = pipe_read, |
891 | .write = bad_pipe_w, |
892 | .poll = pipe_poll, |
893 | .unlocked_ioctl = pipe_ioctl, |
894 | .open = pipe_read_open, |
895 | .release = pipe_read_release, |
896 | .fasync = pipe_read_fasync, |
897 | }; |
898 | |
899 | const struct file_operations write_pipefifo_fops = { |
900 | .llseek = no_llseek, |
901 | .read = bad_pipe_r, |
902 | .write = do_sync_write, |
903 | .aio_write = pipe_write, |
904 | .poll = pipe_poll, |
905 | .unlocked_ioctl = pipe_ioctl, |
906 | .open = pipe_write_open, |
907 | .release = pipe_write_release, |
908 | .fasync = pipe_write_fasync, |
909 | }; |
910 | |
911 | const struct file_operations rdwr_pipefifo_fops = { |
912 | .llseek = no_llseek, |
913 | .read = do_sync_read, |
914 | .aio_read = pipe_read, |
915 | .write = do_sync_write, |
916 | .aio_write = pipe_write, |
917 | .poll = pipe_poll, |
918 | .unlocked_ioctl = pipe_ioctl, |
919 | .open = pipe_rdwr_open, |
920 | .release = pipe_rdwr_release, |
921 | .fasync = pipe_rdwr_fasync, |
922 | }; |
923 | |
924 | struct pipe_inode_info * alloc_pipe_info(struct inode *inode) |
925 | { |
926 | struct pipe_inode_info *pipe; |
927 | |
928 | pipe = kzalloc(sizeof(struct pipe_inode_info), GFP_KERNEL); |
929 | if (pipe) { |
930 | pipe->bufs = kzalloc(sizeof(struct pipe_buffer) * PIPE_DEF_BUFFERS, GFP_KERNEL); |
931 | if (pipe->bufs) { |
932 | init_waitqueue_head(&pipe->wait); |
933 | pipe->r_counter = pipe->w_counter = 1; |
934 | pipe->inode = inode; |
935 | pipe->buffers = PIPE_DEF_BUFFERS; |
936 | return pipe; |
937 | } |
938 | kfree(pipe); |
939 | } |
940 | |
941 | return NULL; |
942 | } |
943 | |
944 | void __free_pipe_info(struct pipe_inode_info *pipe) |
945 | { |
946 | int i; |
947 | |
948 | for (i = 0; i < pipe->buffers; i++) { |
949 | struct pipe_buffer *buf = pipe->bufs + i; |
950 | if (buf->ops) |
951 | buf->ops->release(pipe, buf); |
952 | } |
953 | if (pipe->tmp_page) |
954 | __free_page(pipe->tmp_page); |
955 | kfree(pipe->bufs); |
956 | kfree(pipe); |
957 | } |
958 | |
959 | void free_pipe_info(struct inode *inode) |
960 | { |
961 | __free_pipe_info(inode->i_pipe); |
962 | inode->i_pipe = NULL; |
963 | } |
964 | |
965 | static struct vfsmount *pipe_mnt __read_mostly; |
966 | |
967 | /* |
968 | * pipefs_dname() is called from d_path(). |
969 | */ |
970 | static char *pipefs_dname(struct dentry *dentry, char *buffer, int buflen) |
971 | { |
972 | return dynamic_dname(dentry, buffer, buflen, "pipe:[%lu]", |
973 | dentry->d_inode->i_ino); |
974 | } |
975 | |
976 | static const struct dentry_operations pipefs_dentry_operations = { |
977 | .d_dname = pipefs_dname, |
978 | }; |
979 | |
980 | static struct inode * get_pipe_inode(void) |
981 | { |
982 | struct inode *inode = new_inode_pseudo(pipe_mnt->mnt_sb); |
983 | struct pipe_inode_info *pipe; |
984 | |
985 | if (!inode) |
986 | goto fail_inode; |
987 | |
988 | inode->i_ino = get_next_ino(); |
989 | |
990 | pipe = alloc_pipe_info(inode); |
991 | if (!pipe) |
992 | goto fail_iput; |
993 | inode->i_pipe = pipe; |
994 | |
995 | pipe->readers = pipe->writers = 1; |
996 | inode->i_fop = &rdwr_pipefifo_fops; |
997 | |
998 | /* |
999 | * Mark the inode dirty from the very beginning, |
1000 | * that way it will never be moved to the dirty |
1001 | * list because "mark_inode_dirty()" will think |
1002 | * that it already _is_ on the dirty list. |
1003 | */ |
1004 | inode->i_state = I_DIRTY; |
1005 | inode->i_mode = S_IFIFO | S_IRUSR | S_IWUSR; |
1006 | inode->i_uid = current_fsuid(); |
1007 | inode->i_gid = current_fsgid(); |
1008 | inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; |
1009 | |
1010 | return inode; |
1011 | |
1012 | fail_iput: |
1013 | iput(inode); |
1014 | |
1015 | fail_inode: |
1016 | return NULL; |
1017 | } |
1018 | |
1019 | int create_pipe_files(struct file **res, int flags) |
1020 | { |
1021 | int err; |
1022 | struct inode *inode = get_pipe_inode(); |
1023 | struct file *f; |
1024 | struct path path; |
1025 | static struct qstr name = { .name = "" }; |
1026 | |
1027 | if (!inode) |
1028 | return -ENFILE; |
1029 | |
1030 | err = -ENOMEM; |
1031 | path.dentry = d_alloc_pseudo(pipe_mnt->mnt_sb, &name); |
1032 | if (!path.dentry) |
1033 | goto err_inode; |
1034 | path.mnt = mntget(pipe_mnt); |
1035 | |
1036 | d_instantiate(path.dentry, inode); |
1037 | |
1038 | err = -ENFILE; |
1039 | f = alloc_file(&path, FMODE_WRITE, &write_pipefifo_fops); |
1040 | if (!f) |
1041 | goto err_dentry; |
1042 | |
1043 | f->f_flags = O_WRONLY | (flags & (O_NONBLOCK | O_DIRECT)); |
1044 | |
1045 | res[0] = alloc_file(&path, FMODE_READ, &read_pipefifo_fops); |
1046 | if (!res[0]) |
1047 | goto err_file; |
1048 | |
1049 | path_get(&path); |
1050 | res[0]->f_flags = O_RDONLY | (flags & O_NONBLOCK); |
1051 | res[1] = f; |
1052 | return 0; |
1053 | |
1054 | err_file: |
1055 | put_filp(f); |
1056 | err_dentry: |
1057 | free_pipe_info(inode); |
1058 | path_put(&path); |
1059 | return err; |
1060 | |
1061 | err_inode: |
1062 | free_pipe_info(inode); |
1063 | iput(inode); |
1064 | return err; |
1065 | } |
1066 | |
1067 | int do_pipe_flags(int *fd, int flags) |
1068 | { |
1069 | struct file *files[2]; |
1070 | int error; |
1071 | int fdw, fdr; |
1072 | |
1073 | if (flags & ~(O_CLOEXEC | O_NONBLOCK | O_DIRECT)) |
1074 | return -EINVAL; |
1075 | |
1076 | error = create_pipe_files(files, flags); |
1077 | if (error) |
1078 | return error; |
1079 | |
1080 | error = get_unused_fd_flags(flags); |
1081 | if (error < 0) |
1082 | goto err_read_pipe; |
1083 | fdr = error; |
1084 | |
1085 | error = get_unused_fd_flags(flags); |
1086 | if (error < 0) |
1087 | goto err_fdr; |
1088 | fdw = error; |
1089 | |
1090 | audit_fd_pair(fdr, fdw); |
1091 | fd_install(fdr, files[0]); |
1092 | fd_install(fdw, files[1]); |
1093 | fd[0] = fdr; |
1094 | fd[1] = fdw; |
1095 | |
1096 | return 0; |
1097 | |
1098 | err_fdr: |
1099 | put_unused_fd(fdr); |
1100 | err_read_pipe: |
1101 | fput(files[0]); |
1102 | fput(files[1]); |
1103 | return error; |
1104 | } |
1105 | |
1106 | /* |
1107 | * sys_pipe() is the normal C calling standard for creating |
1108 | * a pipe. It's not the way Unix traditionally does this, though. |
1109 | */ |
1110 | SYSCALL_DEFINE2(pipe2, int __user *, fildes, int, flags) |
1111 | { |
1112 | int fd[2]; |
1113 | int error; |
1114 | |
1115 | error = do_pipe_flags(fd, flags); |
1116 | if (!error) { |
1117 | if (copy_to_user(fildes, fd, sizeof(fd))) { |
1118 | sys_close(fd[0]); |
1119 | sys_close(fd[1]); |
1120 | error = -EFAULT; |
1121 | } |
1122 | } |
1123 | return error; |
1124 | } |
1125 | |
1126 | SYSCALL_DEFINE1(pipe, int __user *, fildes) |
1127 | { |
1128 | return sys_pipe2(fildes, 0); |
1129 | } |
1130 | |
1131 | /* |
1132 | * Allocate a new array of pipe buffers and copy the info over. Returns the |
1133 | * pipe size if successful, or return -ERROR on error. |
1134 | */ |
1135 | static long pipe_set_size(struct pipe_inode_info *pipe, unsigned long nr_pages) |
1136 | { |
1137 | struct pipe_buffer *bufs; |
1138 | |
1139 | /* |
1140 | * We can shrink the pipe, if arg >= pipe->nrbufs. Since we don't |
1141 | * expect a lot of shrink+grow operations, just free and allocate |
1142 | * again like we would do for growing. If the pipe currently |
1143 | * contains more buffers than arg, then return busy. |
1144 | */ |
1145 | if (nr_pages < pipe->nrbufs) |
1146 | return -EBUSY; |
1147 | |
1148 | bufs = kcalloc(nr_pages, sizeof(*bufs), GFP_KERNEL | __GFP_NOWARN); |
1149 | if (unlikely(!bufs)) |
1150 | return -ENOMEM; |
1151 | |
1152 | /* |
1153 | * The pipe array wraps around, so just start the new one at zero |
1154 | * and adjust the indexes. |
1155 | */ |
1156 | if (pipe->nrbufs) { |
1157 | unsigned int tail; |
1158 | unsigned int head; |
1159 | |
1160 | tail = pipe->curbuf + pipe->nrbufs; |
1161 | if (tail < pipe->buffers) |
1162 | tail = 0; |
1163 | else |
1164 | tail &= (pipe->buffers - 1); |
1165 | |
1166 | head = pipe->nrbufs - tail; |
1167 | if (head) |
1168 | memcpy(bufs, pipe->bufs + pipe->curbuf, head * sizeof(struct pipe_buffer)); |
1169 | if (tail) |
1170 | memcpy(bufs + head, pipe->bufs, tail * sizeof(struct pipe_buffer)); |
1171 | } |
1172 | |
1173 | pipe->curbuf = 0; |
1174 | kfree(pipe->bufs); |
1175 | pipe->bufs = bufs; |
1176 | pipe->buffers = nr_pages; |
1177 | return nr_pages * PAGE_SIZE; |
1178 | } |
1179 | |
1180 | /* |
1181 | * Currently we rely on the pipe array holding a power-of-2 number |
1182 | * of pages. |
1183 | */ |
1184 | static inline unsigned int round_pipe_size(unsigned int size) |
1185 | { |
1186 | unsigned long nr_pages; |
1187 | |
1188 | nr_pages = (size + PAGE_SIZE - 1) >> PAGE_SHIFT; |
1189 | return roundup_pow_of_two(nr_pages) << PAGE_SHIFT; |
1190 | } |
1191 | |
1192 | /* |
1193 | * This should work even if CONFIG_PROC_FS isn't set, as proc_dointvec_minmax |
1194 | * will return an error. |
1195 | */ |
1196 | int pipe_proc_fn(struct ctl_table *table, int write, void __user *buf, |
1197 | size_t *lenp, loff_t *ppos) |
1198 | { |
1199 | int ret; |
1200 | |
1201 | ret = proc_dointvec_minmax(table, write, buf, lenp, ppos); |
1202 | if (ret < 0 || !write) |
1203 | return ret; |
1204 | |
1205 | pipe_max_size = round_pipe_size(pipe_max_size); |
1206 | return ret; |
1207 | } |
1208 | |
1209 | /* |
1210 | * After the inode slimming patch, i_pipe/i_bdev/i_cdev share the same |
1211 | * location, so checking ->i_pipe is not enough to verify that this is a |
1212 | * pipe. |
1213 | */ |
1214 | struct pipe_inode_info *get_pipe_info(struct file *file) |
1215 | { |
1216 | struct inode *i = file->f_path.dentry->d_inode; |
1217 | |
1218 | return S_ISFIFO(i->i_mode) ? i->i_pipe : NULL; |
1219 | } |
1220 | |
1221 | long pipe_fcntl(struct file *file, unsigned int cmd, unsigned long arg) |
1222 | { |
1223 | struct pipe_inode_info *pipe; |
1224 | long ret; |
1225 | |
1226 | pipe = get_pipe_info(file); |
1227 | if (!pipe) |
1228 | return -EBADF; |
1229 | |
1230 | mutex_lock(&pipe->inode->i_mutex); |
1231 | |
1232 | switch (cmd) { |
1233 | case F_SETPIPE_SZ: { |
1234 | unsigned int size, nr_pages; |
1235 | |
1236 | size = round_pipe_size(arg); |
1237 | nr_pages = size >> PAGE_SHIFT; |
1238 | |
1239 | ret = -EINVAL; |
1240 | if (!nr_pages) |
1241 | goto out; |
1242 | |
1243 | if (!capable(CAP_SYS_RESOURCE) && size > pipe_max_size) { |
1244 | ret = -EPERM; |
1245 | goto out; |
1246 | } |
1247 | ret = pipe_set_size(pipe, nr_pages); |
1248 | break; |
1249 | } |
1250 | case F_GETPIPE_SZ: |
1251 | ret = pipe->buffers * PAGE_SIZE; |
1252 | break; |
1253 | default: |
1254 | ret = -EINVAL; |
1255 | break; |
1256 | } |
1257 | |
1258 | out: |
1259 | mutex_unlock(&pipe->inode->i_mutex); |
1260 | return ret; |
1261 | } |
1262 | |
1263 | static const struct super_operations pipefs_ops = { |
1264 | .destroy_inode = free_inode_nonrcu, |
1265 | .statfs = simple_statfs, |
1266 | }; |
1267 | |
1268 | /* |
1269 | * pipefs should _never_ be mounted by userland - too much of security hassle, |
1270 | * no real gain from having the whole whorehouse mounted. So we don't need |
1271 | * any operations on the root directory. However, we need a non-trivial |
1272 | * d_name - pipe: will go nicely and kill the special-casing in procfs. |
1273 | */ |
1274 | static struct dentry *pipefs_mount(struct file_system_type *fs_type, |
1275 | int flags, const char *dev_name, void *data) |
1276 | { |
1277 | return mount_pseudo(fs_type, "pipe:", &pipefs_ops, |
1278 | &pipefs_dentry_operations, PIPEFS_MAGIC); |
1279 | } |
1280 | |
1281 | static struct file_system_type pipe_fs_type = { |
1282 | .name = "pipefs", |
1283 | .mount = pipefs_mount, |
1284 | .kill_sb = kill_anon_super, |
1285 | }; |
1286 | |
1287 | static int __init init_pipe_fs(void) |
1288 | { |
1289 | int err = register_filesystem(&pipe_fs_type); |
1290 | |
1291 | if (!err) { |
1292 | pipe_mnt = kern_mount(&pipe_fs_type); |
1293 | if (IS_ERR(pipe_mnt)) { |
1294 | err = PTR_ERR(pipe_mnt); |
1295 | unregister_filesystem(&pipe_fs_type); |
1296 | } |
1297 | } |
1298 | return err; |
1299 | } |
1300 | |
1301 | fs_initcall(init_pipe_fs); |
1302 |
Branches:
ben-wpan
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javiroman/ks7010
jz-2.6.34
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jz-3.13
jz-3.15
jz-3.16
jz-3.18-dt
jz-3.2
jz-3.3
jz-3.4
jz-3.5
jz-3.6
jz-3.6-rc2-pwm
jz-3.9
jz-3.9-clk
jz-3.9-rc8
jz47xx
jz47xx-2.6.38
master
Tags:
od-2011-09-04
od-2011-09-18
v2.6.34-rc5
v2.6.34-rc6
v2.6.34-rc7
v3.9