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1511 lines
36 KiB
1511 lines
36 KiB
// SPDX-License-Identifier: GPL-2.0 |
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/* |
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* linux/fs/pipe.c |
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* |
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* Copyright (C) 1991, 1992, 1999 Linus Torvalds |
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*/ |
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|
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#include <linux/mm.h> |
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#include <linux/file.h> |
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#include <linux/poll.h> |
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#include <linux/slab.h> |
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#include <linux/module.h> |
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#include <linux/init.h> |
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#include <linux/fs.h> |
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#include <linux/log2.h> |
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#include <linux/mount.h> |
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#include <linux/pseudo_fs.h> |
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#include <linux/magic.h> |
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#include <linux/pipe_fs_i.h> |
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#include <linux/uio.h> |
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#include <linux/highmem.h> |
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#include <linux/pagemap.h> |
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#include <linux/audit.h> |
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#include <linux/syscalls.h> |
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#include <linux/fcntl.h> |
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#include <linux/memcontrol.h> |
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#include <linux/watch_queue.h> |
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#include <linux/sysctl.h> |
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|
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#include <linux/uaccess.h> |
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#include <asm/ioctls.h> |
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|
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#include "internal.h" |
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|
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/* |
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* New pipe buffers will be restricted to this size while the user is exceeding |
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* their pipe buffer quota. The general pipe use case needs at least two |
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* buffers: one for data yet to be read, and one for new data. If this is less |
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* than two, then a write to a non-empty pipe may block even if the pipe is not |
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* full. This can occur with GNU make jobserver or similar uses of pipes as |
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* semaphores: multiple processes may be waiting to write tokens back to the |
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* pipe before reading tokens: https://lore.kernel.org/lkml/1628086770.5rn8p04n6j.none@localhost/. |
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* |
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* Users can reduce their pipe buffers with F_SETPIPE_SZ below this at their |
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* own risk, namely: pipe writes to non-full pipes may block until the pipe is |
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* emptied. |
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*/ |
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#define PIPE_MIN_DEF_BUFFERS 2 |
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|
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/* |
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* The max size that a non-root user is allowed to grow the pipe. Can |
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* be set by root in /proc/sys/fs/pipe-max-size |
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*/ |
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static unsigned int pipe_max_size = 1048576; |
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|
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/* Maximum allocatable pages per user. Hard limit is unset by default, soft |
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* matches default values. |
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*/ |
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static unsigned long pipe_user_pages_hard; |
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static unsigned long pipe_user_pages_soft = PIPE_DEF_BUFFERS * INR_OPEN_CUR; |
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|
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/* |
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* We use head and tail indices that aren't masked off, except at the point of |
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* dereference, but rather they're allowed to wrap naturally. This means there |
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* isn't a dead spot in the buffer, but the ring has to be a power of two and |
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* <= 2^31. |
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* -- David Howells 2019-09-23. |
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* |
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* Reads with count = 0 should always return 0. |
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* -- Julian Bradfield 1999-06-07. |
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* |
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* FIFOs and Pipes now generate SIGIO for both readers and writers. |
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* -- Jeremy Elson <[email protected]> 2001-08-16 |
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* |
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* pipe_read & write cleanup |
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* -- Manfred Spraul <[email protected]> 2002-05-09 |
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*/ |
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|
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static void pipe_lock_nested(struct pipe_inode_info *pipe, int subclass) |
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{ |
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if (pipe->files) |
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mutex_lock_nested(&pipe->mutex, subclass); |
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} |
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|
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void pipe_lock(struct pipe_inode_info *pipe) |
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{ |
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/* |
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* pipe_lock() nests non-pipe inode locks (for writing to a file) |
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*/ |
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pipe_lock_nested(pipe, I_MUTEX_PARENT); |
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} |
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EXPORT_SYMBOL(pipe_lock); |
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|
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void pipe_unlock(struct pipe_inode_info *pipe) |
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{ |
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if (pipe->files) |
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mutex_unlock(&pipe->mutex); |
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} |
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EXPORT_SYMBOL(pipe_unlock); |
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|
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static inline void __pipe_lock(struct pipe_inode_info *pipe) |
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{ |
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mutex_lock_nested(&pipe->mutex, I_MUTEX_PARENT); |
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} |
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|
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static inline void __pipe_unlock(struct pipe_inode_info *pipe) |
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{ |
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mutex_unlock(&pipe->mutex); |
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} |
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|
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void pipe_double_lock(struct pipe_inode_info *pipe1, |
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struct pipe_inode_info *pipe2) |
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{ |
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BUG_ON(pipe1 == pipe2); |
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|
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if (pipe1 < pipe2) { |
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pipe_lock_nested(pipe1, I_MUTEX_PARENT); |
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pipe_lock_nested(pipe2, I_MUTEX_CHILD); |
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} else { |
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pipe_lock_nested(pipe2, I_MUTEX_PARENT); |
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pipe_lock_nested(pipe1, I_MUTEX_CHILD); |
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} |
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} |
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|
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static void anon_pipe_buf_release(struct pipe_inode_info *pipe, |
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struct pipe_buffer *buf) |
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{ |
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struct page *page = buf->page; |
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|
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/* |
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* If nobody else uses this page, and we don't already have a |
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* temporary page, let's keep track of it as a one-deep |
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* allocation cache. (Otherwise just release our reference to it) |
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*/ |
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if (page_count(page) == 1 && !pipe->tmp_page) |
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pipe->tmp_page = page; |
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else |
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put_page(page); |
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} |
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|
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static bool anon_pipe_buf_try_steal(struct pipe_inode_info *pipe, |
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struct pipe_buffer *buf) |
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{ |
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struct page *page = buf->page; |
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|
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if (page_count(page) != 1) |
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return false; |
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memcg_kmem_uncharge_page(page, 0); |
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__SetPageLocked(page); |
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return true; |
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} |
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|
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/** |
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* generic_pipe_buf_try_steal - attempt to take ownership of a &pipe_buffer |
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* @pipe: the pipe that the buffer belongs to |
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* @buf: the buffer to attempt to steal |
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* |
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* Description: |
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* This function attempts to steal the &struct page attached to |
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* @buf. If successful, this function returns 0 and returns with |
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* the page locked. The caller may then reuse the page for whatever |
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* he wishes; the typical use is insertion into a different file |
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* page cache. |
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*/ |
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bool generic_pipe_buf_try_steal(struct pipe_inode_info *pipe, |
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struct pipe_buffer *buf) |
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{ |
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struct page *page = buf->page; |
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|
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/* |
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* A reference of one is golden, that means that the owner of this |
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* page is the only one holding a reference to it. lock the page |
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* and return OK. |
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*/ |
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if (page_count(page) == 1) { |
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lock_page(page); |
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return true; |
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} |
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return false; |
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} |
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EXPORT_SYMBOL(generic_pipe_buf_try_steal); |
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|
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/** |
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* generic_pipe_buf_get - get a reference to a &struct pipe_buffer |
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* @pipe: the pipe that the buffer belongs to |
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* @buf: the buffer to get a reference to |
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* |
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* Description: |
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* This function grabs an extra reference to @buf. It's used in |
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* the tee() system call, when we duplicate the buffers in one |
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* pipe into another. |
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*/ |
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bool generic_pipe_buf_get(struct pipe_inode_info *pipe, struct pipe_buffer *buf) |
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{ |
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return try_get_page(buf->page); |
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} |
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EXPORT_SYMBOL(generic_pipe_buf_get); |
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|
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/** |
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* generic_pipe_buf_release - put a reference to a &struct pipe_buffer |
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* @pipe: the pipe that the buffer belongs to |
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* @buf: the buffer to put a reference to |
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* |
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* Description: |
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* This function releases a reference to @buf. |
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*/ |
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void generic_pipe_buf_release(struct pipe_inode_info *pipe, |
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struct pipe_buffer *buf) |
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{ |
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put_page(buf->page); |
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} |
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EXPORT_SYMBOL(generic_pipe_buf_release); |
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|
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static const struct pipe_buf_operations anon_pipe_buf_ops = { |
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.release = anon_pipe_buf_release, |
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.try_steal = anon_pipe_buf_try_steal, |
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.get = generic_pipe_buf_get, |
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}; |
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|
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/* Done while waiting without holding the pipe lock - thus the READ_ONCE() */ |
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static inline bool pipe_readable(const struct pipe_inode_info *pipe) |
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{ |
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unsigned int head = READ_ONCE(pipe->head); |
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unsigned int tail = READ_ONCE(pipe->tail); |
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unsigned int writers = READ_ONCE(pipe->writers); |
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|
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return !pipe_empty(head, tail) || !writers; |
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} |
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|
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static ssize_t |
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pipe_read(struct kiocb *iocb, struct iov_iter *to) |
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{ |
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size_t total_len = iov_iter_count(to); |
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struct file *filp = iocb->ki_filp; |
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struct pipe_inode_info *pipe = filp->private_data; |
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bool was_full, wake_next_reader = false; |
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ssize_t ret; |
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|
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/* Null read succeeds. */ |
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if (unlikely(total_len == 0)) |
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return 0; |
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|
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ret = 0; |
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__pipe_lock(pipe); |
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|
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/* |
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* We only wake up writers if the pipe was full when we started |
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* reading in order to avoid unnecessary wakeups. |
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* |
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* But when we do wake up writers, we do so using a sync wakeup |
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* (WF_SYNC), because we want them to get going and generate more |
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* data for us. |
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*/ |
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was_full = pipe_full(pipe->head, pipe->tail, pipe->max_usage); |
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for (;;) { |
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/* Read ->head with a barrier vs post_one_notification() */ |
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unsigned int head = smp_load_acquire(&pipe->head); |
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unsigned int tail = pipe->tail; |
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unsigned int mask = pipe->ring_size - 1; |
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|
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#ifdef CONFIG_WATCH_QUEUE |
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if (pipe->note_loss) { |
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struct watch_notification n; |
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|
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if (total_len < 8) { |
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if (ret == 0) |
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ret = -ENOBUFS; |
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break; |
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} |
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|
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n.type = WATCH_TYPE_META; |
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n.subtype = WATCH_META_LOSS_NOTIFICATION; |
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n.info = watch_sizeof(n); |
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if (copy_to_iter(&n, sizeof(n), to) != sizeof(n)) { |
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if (ret == 0) |
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ret = -EFAULT; |
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break; |
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} |
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ret += sizeof(n); |
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total_len -= sizeof(n); |
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pipe->note_loss = false; |
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} |
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#endif |
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|
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if (!pipe_empty(head, tail)) { |
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struct pipe_buffer *buf = &pipe->bufs[tail & mask]; |
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size_t chars = buf->len; |
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size_t written; |
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int error; |
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|
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if (chars > total_len) { |
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if (buf->flags & PIPE_BUF_FLAG_WHOLE) { |
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if (ret == 0) |
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ret = -ENOBUFS; |
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break; |
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} |
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chars = total_len; |
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} |
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|
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error = pipe_buf_confirm(pipe, buf); |
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if (error) { |
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if (!ret) |
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ret = error; |
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break; |
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} |
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|
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written = copy_page_to_iter(buf->page, buf->offset, chars, to); |
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if (unlikely(written < chars)) { |
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if (!ret) |
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ret = -EFAULT; |
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break; |
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} |
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ret += chars; |
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buf->offset += chars; |
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buf->len -= chars; |
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|
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/* Was it a packet buffer? Clean up and exit */ |
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if (buf->flags & PIPE_BUF_FLAG_PACKET) { |
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total_len = chars; |
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buf->len = 0; |
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} |
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|
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if (!buf->len) { |
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pipe_buf_release(pipe, buf); |
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spin_lock_irq(&pipe->rd_wait.lock); |
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#ifdef CONFIG_WATCH_QUEUE |
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if (buf->flags & PIPE_BUF_FLAG_LOSS) |
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pipe->note_loss = true; |
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#endif |
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tail++; |
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pipe->tail = tail; |
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spin_unlock_irq(&pipe->rd_wait.lock); |
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} |
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total_len -= chars; |
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if (!total_len) |
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break; /* common path: read succeeded */ |
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if (!pipe_empty(head, tail)) /* More to do? */ |
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continue; |
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} |
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|
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if (!pipe->writers) |
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break; |
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if (ret) |
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break; |
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if (filp->f_flags & O_NONBLOCK) { |
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ret = -EAGAIN; |
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break; |
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} |
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__pipe_unlock(pipe); |
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|
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/* |
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* We only get here if we didn't actually read anything. |
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* |
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* However, we could have seen (and removed) a zero-sized |
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* pipe buffer, and might have made space in the buffers |
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* that way. |
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* |
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* You can't make zero-sized pipe buffers by doing an empty |
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* write (not even in packet mode), but they can happen if |
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* the writer gets an EFAULT when trying to fill a buffer |
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* that already got allocated and inserted in the buffer |
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* array. |
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* |
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* So we still need to wake up any pending writers in the |
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* _very_ unlikely case that the pipe was full, but we got |
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* no data. |
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*/ |
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if (unlikely(was_full)) |
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wake_up_interruptible_sync_poll(&pipe->wr_wait, EPOLLOUT | EPOLLWRNORM); |
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kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT); |
|
|
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/* |
|
* But because we didn't read anything, at this point we can |
|
* just return directly with -ERESTARTSYS if we're interrupted, |
|
* since we've done any required wakeups and there's no need |
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* to mark anything accessed. And we've dropped the lock. |
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*/ |
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if (wait_event_interruptible_exclusive(pipe->rd_wait, pipe_readable(pipe)) < 0) |
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return -ERESTARTSYS; |
|
|
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__pipe_lock(pipe); |
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was_full = pipe_full(pipe->head, pipe->tail, pipe->max_usage); |
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wake_next_reader = true; |
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} |
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if (pipe_empty(pipe->head, pipe->tail)) |
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wake_next_reader = false; |
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__pipe_unlock(pipe); |
|
|
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if (was_full) |
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wake_up_interruptible_sync_poll(&pipe->wr_wait, EPOLLOUT | EPOLLWRNORM); |
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if (wake_next_reader) |
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wake_up_interruptible_sync_poll(&pipe->rd_wait, EPOLLIN | EPOLLRDNORM); |
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kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT); |
|
if (ret > 0) |
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file_accessed(filp); |
|
return ret; |
|
} |
|
|
|
static inline int is_packetized(struct file *file) |
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{ |
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return (file->f_flags & O_DIRECT) != 0; |
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} |
|
|
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/* Done while waiting without holding the pipe lock - thus the READ_ONCE() */ |
|
static inline bool pipe_writable(const struct pipe_inode_info *pipe) |
|
{ |
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unsigned int head = READ_ONCE(pipe->head); |
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unsigned int tail = READ_ONCE(pipe->tail); |
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unsigned int max_usage = READ_ONCE(pipe->max_usage); |
|
|
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return !pipe_full(head, tail, max_usage) || |
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!READ_ONCE(pipe->readers); |
|
} |
|
|
|
static ssize_t |
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pipe_write(struct kiocb *iocb, struct iov_iter *from) |
|
{ |
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struct file *filp = iocb->ki_filp; |
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struct pipe_inode_info *pipe = filp->private_data; |
|
unsigned int head; |
|
ssize_t ret = 0; |
|
size_t total_len = iov_iter_count(from); |
|
ssize_t chars; |
|
bool was_empty = false; |
|
bool wake_next_writer = false; |
|
|
|
/* Null write succeeds. */ |
|
if (unlikely(total_len == 0)) |
|
return 0; |
|
|
|
__pipe_lock(pipe); |
|
|
|
if (!pipe->readers) { |
|
send_sig(SIGPIPE, current, 0); |
|
ret = -EPIPE; |
|
goto out; |
|
} |
|
|
|
#ifdef CONFIG_WATCH_QUEUE |
|
if (pipe->watch_queue) { |
|
ret = -EXDEV; |
|
goto out; |
|
} |
|
#endif |
|
|
|
/* |
|
* If it wasn't empty we try to merge new data into |
|
* the last buffer. |
|
* |
|
* That naturally merges small writes, but it also |
|
* page-aligns the rest of the writes for large writes |
|
* spanning multiple pages. |
|
*/ |
|
head = pipe->head; |
|
was_empty = pipe_empty(head, pipe->tail); |
|
chars = total_len & (PAGE_SIZE-1); |
|
if (chars && !was_empty) { |
|
unsigned int mask = pipe->ring_size - 1; |
|
struct pipe_buffer *buf = &pipe->bufs[(head - 1) & mask]; |
|
int offset = buf->offset + buf->len; |
|
|
|
if ((buf->flags & PIPE_BUF_FLAG_CAN_MERGE) && |
|
offset + chars <= PAGE_SIZE) { |
|
ret = pipe_buf_confirm(pipe, buf); |
|
if (ret) |
|
goto out; |
|
|
|
ret = copy_page_from_iter(buf->page, offset, chars, from); |
|
if (unlikely(ret < chars)) { |
|
ret = -EFAULT; |
|
goto out; |
|
} |
|
|
|
buf->len += ret; |
|
if (!iov_iter_count(from)) |
|
goto out; |
|
} |
|
} |
|
|
|
for (;;) { |
|
if (!pipe->readers) { |
|
send_sig(SIGPIPE, current, 0); |
|
if (!ret) |
|
ret = -EPIPE; |
|
break; |
|
} |
|
|
|
head = pipe->head; |
|
if (!pipe_full(head, pipe->tail, pipe->max_usage)) { |
|
unsigned int mask = pipe->ring_size - 1; |
|
struct pipe_buffer *buf = &pipe->bufs[head & mask]; |
|
struct page *page = pipe->tmp_page; |
|
int copied; |
|
|
|
if (!page) { |
|
page = alloc_page(GFP_HIGHUSER | __GFP_ACCOUNT); |
|
if (unlikely(!page)) { |
|
ret = ret ? : -ENOMEM; |
|
break; |
|
} |
|
pipe->tmp_page = page; |
|
} |
|
|
|
/* Allocate a slot in the ring in advance and attach an |
|
* empty buffer. If we fault or otherwise fail to use |
|
* it, either the reader will consume it or it'll still |
|
* be there for the next write. |
|
*/ |
|
spin_lock_irq(&pipe->rd_wait.lock); |
|
|
|
head = pipe->head; |
|
if (pipe_full(head, pipe->tail, pipe->max_usage)) { |
|
spin_unlock_irq(&pipe->rd_wait.lock); |
|
continue; |
|
} |
|
|
|
pipe->head = head + 1; |
|
spin_unlock_irq(&pipe->rd_wait.lock); |
|
|
|
/* Insert it into the buffer array */ |
|
buf = &pipe->bufs[head & mask]; |
|
buf->page = page; |
|
buf->ops = &anon_pipe_buf_ops; |
|
buf->offset = 0; |
|
buf->len = 0; |
|
if (is_packetized(filp)) |
|
buf->flags = PIPE_BUF_FLAG_PACKET; |
|
else |
|
buf->flags = PIPE_BUF_FLAG_CAN_MERGE; |
|
pipe->tmp_page = NULL; |
|
|
|
copied = copy_page_from_iter(page, 0, PAGE_SIZE, from); |
|
if (unlikely(copied < PAGE_SIZE && iov_iter_count(from))) { |
|
if (!ret) |
|
ret = -EFAULT; |
|
break; |
|
} |
|
ret += copied; |
|
buf->offset = 0; |
|
buf->len = copied; |
|
|
|
if (!iov_iter_count(from)) |
|
break; |
|
} |
|
|
|
if (!pipe_full(head, pipe->tail, pipe->max_usage)) |
|
continue; |
|
|
|
/* Wait for buffer space to become available. */ |
|
if (filp->f_flags & O_NONBLOCK) { |
|
if (!ret) |
|
ret = -EAGAIN; |
|
break; |
|
} |
|
if (signal_pending(current)) { |
|
if (!ret) |
|
ret = -ERESTARTSYS; |
|
break; |
|
} |
|
|
|
/* |
|
* We're going to release the pipe lock and wait for more |
|
* space. We wake up any readers if necessary, and then |
|
* after waiting we need to re-check whether the pipe |
|
* become empty while we dropped the lock. |
|
*/ |
|
__pipe_unlock(pipe); |
|
if (was_empty) |
|
wake_up_interruptible_sync_poll(&pipe->rd_wait, EPOLLIN | EPOLLRDNORM); |
|
kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); |
|
wait_event_interruptible_exclusive(pipe->wr_wait, pipe_writable(pipe)); |
|
__pipe_lock(pipe); |
|
was_empty = pipe_empty(pipe->head, pipe->tail); |
|
wake_next_writer = true; |
|
} |
|
out: |
|
if (pipe_full(pipe->head, pipe->tail, pipe->max_usage)) |
|
wake_next_writer = false; |
|
__pipe_unlock(pipe); |
|
|
|
/* |
|
* If we do do a wakeup event, we do a 'sync' wakeup, because we |
|
* want the reader to start processing things asap, rather than |
|
* leave the data pending. |
|
* |
|
* This is particularly important for small writes, because of |
|
* how (for example) the GNU make jobserver uses small writes to |
|
* wake up pending jobs |
|
* |
|
* Epoll nonsensically wants a wakeup whether the pipe |
|
* was already empty or not. |
|
*/ |
|
if (was_empty || pipe->poll_usage) |
|
wake_up_interruptible_sync_poll(&pipe->rd_wait, EPOLLIN | EPOLLRDNORM); |
|
kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); |
|
if (wake_next_writer) |
|
wake_up_interruptible_sync_poll(&pipe->wr_wait, EPOLLOUT | EPOLLWRNORM); |
|
if (ret > 0 && sb_start_write_trylock(file_inode(filp)->i_sb)) { |
|
int err = file_update_time(filp); |
|
if (err) |
|
ret = err; |
|
sb_end_write(file_inode(filp)->i_sb); |
|
} |
|
return ret; |
|
} |
|
|
|
static long pipe_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) |
|
{ |
|
struct pipe_inode_info *pipe = filp->private_data; |
|
unsigned int count, head, tail, mask; |
|
|
|
switch (cmd) { |
|
case FIONREAD: |
|
__pipe_lock(pipe); |
|
count = 0; |
|
head = pipe->head; |
|
tail = pipe->tail; |
|
mask = pipe->ring_size - 1; |
|
|
|
while (tail != head) { |
|
count += pipe->bufs[tail & mask].len; |
|
tail++; |
|
} |
|
__pipe_unlock(pipe); |
|
|
|
return put_user(count, (int __user *)arg); |
|
|
|
#ifdef CONFIG_WATCH_QUEUE |
|
case IOC_WATCH_QUEUE_SET_SIZE: { |
|
int ret; |
|
__pipe_lock(pipe); |
|
ret = watch_queue_set_size(pipe, arg); |
|
__pipe_unlock(pipe); |
|
return ret; |
|
} |
|
|
|
case IOC_WATCH_QUEUE_SET_FILTER: |
|
return watch_queue_set_filter( |
|
pipe, (struct watch_notification_filter __user *)arg); |
|
#endif |
|
|
|
default: |
|
return -ENOIOCTLCMD; |
|
} |
|
} |
|
|
|
/* No kernel lock held - fine */ |
|
static __poll_t |
|
pipe_poll(struct file *filp, poll_table *wait) |
|
{ |
|
__poll_t mask; |
|
struct pipe_inode_info *pipe = filp->private_data; |
|
unsigned int head, tail; |
|
|
|
/* Epoll has some historical nasty semantics, this enables them */ |
|
WRITE_ONCE(pipe->poll_usage, true); |
|
|
|
/* |
|
* Reading pipe state only -- no need for acquiring the semaphore. |
|
* |
|
* But because this is racy, the code has to add the |
|
* entry to the poll table _first_ .. |
|
*/ |
|
if (filp->f_mode & FMODE_READ) |
|
poll_wait(filp, &pipe->rd_wait, wait); |
|
if (filp->f_mode & FMODE_WRITE) |
|
poll_wait(filp, &pipe->wr_wait, wait); |
|
|
|
/* |
|
* .. and only then can you do the racy tests. That way, |
|
* if something changes and you got it wrong, the poll |
|
* table entry will wake you up and fix it. |
|
*/ |
|
head = READ_ONCE(pipe->head); |
|
tail = READ_ONCE(pipe->tail); |
|
|
|
mask = 0; |
|
if (filp->f_mode & FMODE_READ) { |
|
if (!pipe_empty(head, tail)) |
|
mask |= EPOLLIN | EPOLLRDNORM; |
|
if (!pipe->writers && filp->f_version != pipe->w_counter) |
|
mask |= EPOLLHUP; |
|
} |
|
|
|
if (filp->f_mode & FMODE_WRITE) { |
|
if (!pipe_full(head, tail, pipe->max_usage)) |
|
mask |= EPOLLOUT | EPOLLWRNORM; |
|
/* |
|
* Most Unices do not set EPOLLERR for FIFOs but on Linux they |
|
* behave exactly like pipes for poll(). |
|
*/ |
|
if (!pipe->readers) |
|
mask |= EPOLLERR; |
|
} |
|
|
|
return mask; |
|
} |
|
|
|
static void put_pipe_info(struct inode *inode, struct pipe_inode_info *pipe) |
|
{ |
|
int kill = 0; |
|
|
|
spin_lock(&inode->i_lock); |
|
if (!--pipe->files) { |
|
inode->i_pipe = NULL; |
|
kill = 1; |
|
} |
|
spin_unlock(&inode->i_lock); |
|
|
|
if (kill) |
|
free_pipe_info(pipe); |
|
} |
|
|
|
static int |
|
pipe_release(struct inode *inode, struct file *file) |
|
{ |
|
struct pipe_inode_info *pipe = file->private_data; |
|
|
|
__pipe_lock(pipe); |
|
if (file->f_mode & FMODE_READ) |
|
pipe->readers--; |
|
if (file->f_mode & FMODE_WRITE) |
|
pipe->writers--; |
|
|
|
/* Was that the last reader or writer, but not the other side? */ |
|
if (!pipe->readers != !pipe->writers) { |
|
wake_up_interruptible_all(&pipe->rd_wait); |
|
wake_up_interruptible_all(&pipe->wr_wait); |
|
kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); |
|
kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT); |
|
} |
|
__pipe_unlock(pipe); |
|
|
|
put_pipe_info(inode, pipe); |
|
return 0; |
|
} |
|
|
|
static int |
|
pipe_fasync(int fd, struct file *filp, int on) |
|
{ |
|
struct pipe_inode_info *pipe = filp->private_data; |
|
int retval = 0; |
|
|
|
__pipe_lock(pipe); |
|
if (filp->f_mode & FMODE_READ) |
|
retval = fasync_helper(fd, filp, on, &pipe->fasync_readers); |
|
if ((filp->f_mode & FMODE_WRITE) && retval >= 0) { |
|
retval = fasync_helper(fd, filp, on, &pipe->fasync_writers); |
|
if (retval < 0 && (filp->f_mode & FMODE_READ)) |
|
/* this can happen only if on == T */ |
|
fasync_helper(-1, filp, 0, &pipe->fasync_readers); |
|
} |
|
__pipe_unlock(pipe); |
|
return retval; |
|
} |
|
|
|
unsigned long account_pipe_buffers(struct user_struct *user, |
|
unsigned long old, unsigned long new) |
|
{ |
|
return atomic_long_add_return(new - old, &user->pipe_bufs); |
|
} |
|
|
|
bool too_many_pipe_buffers_soft(unsigned long user_bufs) |
|
{ |
|
unsigned long soft_limit = READ_ONCE(pipe_user_pages_soft); |
|
|
|
return soft_limit && user_bufs > soft_limit; |
|
} |
|
|
|
bool too_many_pipe_buffers_hard(unsigned long user_bufs) |
|
{ |
|
unsigned long hard_limit = READ_ONCE(pipe_user_pages_hard); |
|
|
|
return hard_limit && user_bufs > hard_limit; |
|
} |
|
|
|
bool pipe_is_unprivileged_user(void) |
|
{ |
|
return !capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN); |
|
} |
|
|
|
struct pipe_inode_info *alloc_pipe_info(void) |
|
{ |
|
struct pipe_inode_info *pipe; |
|
unsigned long pipe_bufs = PIPE_DEF_BUFFERS; |
|
struct user_struct *user = get_current_user(); |
|
unsigned long user_bufs; |
|
unsigned int max_size = READ_ONCE(pipe_max_size); |
|
|
|
pipe = kzalloc(sizeof(struct pipe_inode_info), GFP_KERNEL_ACCOUNT); |
|
if (pipe == NULL) |
|
goto out_free_uid; |
|
|
|
if (pipe_bufs * PAGE_SIZE > max_size && !capable(CAP_SYS_RESOURCE)) |
|
pipe_bufs = max_size >> PAGE_SHIFT; |
|
|
|
user_bufs = account_pipe_buffers(user, 0, pipe_bufs); |
|
|
|
if (too_many_pipe_buffers_soft(user_bufs) && pipe_is_unprivileged_user()) { |
|
user_bufs = account_pipe_buffers(user, pipe_bufs, PIPE_MIN_DEF_BUFFERS); |
|
pipe_bufs = PIPE_MIN_DEF_BUFFERS; |
|
} |
|
|
|
if (too_many_pipe_buffers_hard(user_bufs) && pipe_is_unprivileged_user()) |
|
goto out_revert_acct; |
|
|
|
pipe->bufs = kcalloc(pipe_bufs, sizeof(struct pipe_buffer), |
|
GFP_KERNEL_ACCOUNT); |
|
|
|
if (pipe->bufs) { |
|
init_waitqueue_head(&pipe->rd_wait); |
|
init_waitqueue_head(&pipe->wr_wait); |
|
pipe->r_counter = pipe->w_counter = 1; |
|
pipe->max_usage = pipe_bufs; |
|
pipe->ring_size = pipe_bufs; |
|
pipe->nr_accounted = pipe_bufs; |
|
pipe->user = user; |
|
mutex_init(&pipe->mutex); |
|
return pipe; |
|
} |
|
|
|
out_revert_acct: |
|
(void) account_pipe_buffers(user, pipe_bufs, 0); |
|
kfree(pipe); |
|
out_free_uid: |
|
free_uid(user); |
|
return NULL; |
|
} |
|
|
|
void free_pipe_info(struct pipe_inode_info *pipe) |
|
{ |
|
unsigned int i; |
|
|
|
#ifdef CONFIG_WATCH_QUEUE |
|
if (pipe->watch_queue) |
|
watch_queue_clear(pipe->watch_queue); |
|
#endif |
|
|
|
(void) account_pipe_buffers(pipe->user, pipe->nr_accounted, 0); |
|
free_uid(pipe->user); |
|
for (i = 0; i < pipe->ring_size; i++) { |
|
struct pipe_buffer *buf = pipe->bufs + i; |
|
if (buf->ops) |
|
pipe_buf_release(pipe, buf); |
|
} |
|
#ifdef CONFIG_WATCH_QUEUE |
|
if (pipe->watch_queue) |
|
put_watch_queue(pipe->watch_queue); |
|
#endif |
|
if (pipe->tmp_page) |
|
__free_page(pipe->tmp_page); |
|
kfree(pipe->bufs); |
|
kfree(pipe); |
|
} |
|
|
|
static struct vfsmount *pipe_mnt __read_mostly; |
|
|
|
/* |
|
* pipefs_dname() is called from d_path(). |
|
*/ |
|
static char *pipefs_dname(struct dentry *dentry, char *buffer, int buflen) |
|
{ |
|
return dynamic_dname(buffer, buflen, "pipe:[%lu]", |
|
d_inode(dentry)->i_ino); |
|
} |
|
|
|
static const struct dentry_operations pipefs_dentry_operations = { |
|
.d_dname = pipefs_dname, |
|
}; |
|
|
|
static struct inode * get_pipe_inode(void) |
|
{ |
|
struct inode *inode = new_inode_pseudo(pipe_mnt->mnt_sb); |
|
struct pipe_inode_info *pipe; |
|
|
|
if (!inode) |
|
goto fail_inode; |
|
|
|
inode->i_ino = get_next_ino(); |
|
|
|
pipe = alloc_pipe_info(); |
|
if (!pipe) |
|
goto fail_iput; |
|
|
|
inode->i_pipe = pipe; |
|
pipe->files = 2; |
|
pipe->readers = pipe->writers = 1; |
|
inode->i_fop = &pipefifo_fops; |
|
|
|
/* |
|
* Mark the inode dirty from the very beginning, |
|
* that way it will never be moved to the dirty |
|
* list because "mark_inode_dirty()" will think |
|
* that it already _is_ on the dirty list. |
|
*/ |
|
inode->i_state = I_DIRTY; |
|
inode->i_mode = S_IFIFO | S_IRUSR | S_IWUSR; |
|
inode->i_uid = current_fsuid(); |
|
inode->i_gid = current_fsgid(); |
|
inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode); |
|
|
|
return inode; |
|
|
|
fail_iput: |
|
iput(inode); |
|
|
|
fail_inode: |
|
return NULL; |
|
} |
|
|
|
int create_pipe_files(struct file **res, int flags) |
|
{ |
|
struct inode *inode = get_pipe_inode(); |
|
struct file *f; |
|
int error; |
|
|
|
if (!inode) |
|
return -ENFILE; |
|
|
|
if (flags & O_NOTIFICATION_PIPE) { |
|
error = watch_queue_init(inode->i_pipe); |
|
if (error) { |
|
free_pipe_info(inode->i_pipe); |
|
iput(inode); |
|
return error; |
|
} |
|
} |
|
|
|
f = alloc_file_pseudo(inode, pipe_mnt, "", |
|
O_WRONLY | (flags & (O_NONBLOCK | O_DIRECT)), |
|
&pipefifo_fops); |
|
if (IS_ERR(f)) { |
|
free_pipe_info(inode->i_pipe); |
|
iput(inode); |
|
return PTR_ERR(f); |
|
} |
|
|
|
f->private_data = inode->i_pipe; |
|
|
|
res[0] = alloc_file_clone(f, O_RDONLY | (flags & O_NONBLOCK), |
|
&pipefifo_fops); |
|
if (IS_ERR(res[0])) { |
|
put_pipe_info(inode, inode->i_pipe); |
|
fput(f); |
|
return PTR_ERR(res[0]); |
|
} |
|
res[0]->private_data = inode->i_pipe; |
|
res[1] = f; |
|
stream_open(inode, res[0]); |
|
stream_open(inode, res[1]); |
|
return 0; |
|
} |
|
|
|
static int __do_pipe_flags(int *fd, struct file **files, int flags) |
|
{ |
|
int error; |
|
int fdw, fdr; |
|
|
|
if (flags & ~(O_CLOEXEC | O_NONBLOCK | O_DIRECT | O_NOTIFICATION_PIPE)) |
|
return -EINVAL; |
|
|
|
error = create_pipe_files(files, flags); |
|
if (error) |
|
return error; |
|
|
|
error = get_unused_fd_flags(flags); |
|
if (error < 0) |
|
goto err_read_pipe; |
|
fdr = error; |
|
|
|
error = get_unused_fd_flags(flags); |
|
if (error < 0) |
|
goto err_fdr; |
|
fdw = error; |
|
|
|
audit_fd_pair(fdr, fdw); |
|
fd[0] = fdr; |
|
fd[1] = fdw; |
|
return 0; |
|
|
|
err_fdr: |
|
put_unused_fd(fdr); |
|
err_read_pipe: |
|
fput(files[0]); |
|
fput(files[1]); |
|
return error; |
|
} |
|
|
|
int do_pipe_flags(int *fd, int flags) |
|
{ |
|
struct file *files[2]; |
|
int error = __do_pipe_flags(fd, files, flags); |
|
if (!error) { |
|
fd_install(fd[0], files[0]); |
|
fd_install(fd[1], files[1]); |
|
} |
|
return error; |
|
} |
|
|
|
/* |
|
* sys_pipe() is the normal C calling standard for creating |
|
* a pipe. It's not the way Unix traditionally does this, though. |
|
*/ |
|
static int do_pipe2(int __user *fildes, int flags) |
|
{ |
|
struct file *files[2]; |
|
int fd[2]; |
|
int error; |
|
|
|
error = __do_pipe_flags(fd, files, flags); |
|
if (!error) { |
|
if (unlikely(copy_to_user(fildes, fd, sizeof(fd)))) { |
|
fput(files[0]); |
|
fput(files[1]); |
|
put_unused_fd(fd[0]); |
|
put_unused_fd(fd[1]); |
|
error = -EFAULT; |
|
} else { |
|
fd_install(fd[0], files[0]); |
|
fd_install(fd[1], files[1]); |
|
} |
|
} |
|
return error; |
|
} |
|
|
|
SYSCALL_DEFINE2(pipe2, int __user *, fildes, int, flags) |
|
{ |
|
return do_pipe2(fildes, flags); |
|
} |
|
|
|
SYSCALL_DEFINE1(pipe, int __user *, fildes) |
|
{ |
|
return do_pipe2(fildes, 0); |
|
} |
|
|
|
/* |
|
* This is the stupid "wait for pipe to be readable or writable" |
|
* model. |
|
* |
|
* See pipe_read/write() for the proper kind of exclusive wait, |
|
* but that requires that we wake up any other readers/writers |
|
* if we then do not end up reading everything (ie the whole |
|
* "wake_next_reader/writer" logic in pipe_read/write()). |
|
*/ |
|
void pipe_wait_readable(struct pipe_inode_info *pipe) |
|
{ |
|
pipe_unlock(pipe); |
|
wait_event_interruptible(pipe->rd_wait, pipe_readable(pipe)); |
|
pipe_lock(pipe); |
|
} |
|
|
|
void pipe_wait_writable(struct pipe_inode_info *pipe) |
|
{ |
|
pipe_unlock(pipe); |
|
wait_event_interruptible(pipe->wr_wait, pipe_writable(pipe)); |
|
pipe_lock(pipe); |
|
} |
|
|
|
/* |
|
* This depends on both the wait (here) and the wakeup (wake_up_partner) |
|
* holding the pipe lock, so "*cnt" is stable and we know a wakeup cannot |
|
* race with the count check and waitqueue prep. |
|
* |
|
* Normally in order to avoid races, you'd do the prepare_to_wait() first, |
|
* then check the condition you're waiting for, and only then sleep. But |
|
* because of the pipe lock, we can check the condition before being on |
|
* the wait queue. |
|
* |
|
* We use the 'rd_wait' waitqueue for pipe partner waiting. |
|
*/ |
|
static int wait_for_partner(struct pipe_inode_info *pipe, unsigned int *cnt) |
|
{ |
|
DEFINE_WAIT(rdwait); |
|
int cur = *cnt; |
|
|
|
while (cur == *cnt) { |
|
prepare_to_wait(&pipe->rd_wait, &rdwait, TASK_INTERRUPTIBLE); |
|
pipe_unlock(pipe); |
|
schedule(); |
|
finish_wait(&pipe->rd_wait, &rdwait); |
|
pipe_lock(pipe); |
|
if (signal_pending(current)) |
|
break; |
|
} |
|
return cur == *cnt ? -ERESTARTSYS : 0; |
|
} |
|
|
|
static void wake_up_partner(struct pipe_inode_info *pipe) |
|
{ |
|
wake_up_interruptible_all(&pipe->rd_wait); |
|
} |
|
|
|
static int fifo_open(struct inode *inode, struct file *filp) |
|
{ |
|
struct pipe_inode_info *pipe; |
|
bool is_pipe = inode->i_sb->s_magic == PIPEFS_MAGIC; |
|
int ret; |
|
|
|
filp->f_version = 0; |
|
|
|
spin_lock(&inode->i_lock); |
|
if (inode->i_pipe) { |
|
pipe = inode->i_pipe; |
|
pipe->files++; |
|
spin_unlock(&inode->i_lock); |
|
} else { |
|
spin_unlock(&inode->i_lock); |
|
pipe = alloc_pipe_info(); |
|
if (!pipe) |
|
return -ENOMEM; |
|
pipe->files = 1; |
|
spin_lock(&inode->i_lock); |
|
if (unlikely(inode->i_pipe)) { |
|
inode->i_pipe->files++; |
|
spin_unlock(&inode->i_lock); |
|
free_pipe_info(pipe); |
|
pipe = inode->i_pipe; |
|
} else { |
|
inode->i_pipe = pipe; |
|
spin_unlock(&inode->i_lock); |
|
} |
|
} |
|
filp->private_data = pipe; |
|
/* OK, we have a pipe and it's pinned down */ |
|
|
|
__pipe_lock(pipe); |
|
|
|
/* We can only do regular read/write on fifos */ |
|
stream_open(inode, filp); |
|
|
|
switch (filp->f_mode & (FMODE_READ | FMODE_WRITE)) { |
|
case FMODE_READ: |
|
/* |
|
* O_RDONLY |
|
* POSIX.1 says that O_NONBLOCK means return with the FIFO |
|
* opened, even when there is no process writing the FIFO. |
|
*/ |
|
pipe->r_counter++; |
|
if (pipe->readers++ == 0) |
|
wake_up_partner(pipe); |
|
|
|
if (!is_pipe && !pipe->writers) { |
|
if ((filp->f_flags & O_NONBLOCK)) { |
|
/* suppress EPOLLHUP until we have |
|
* seen a writer */ |
|
filp->f_version = pipe->w_counter; |
|
} else { |
|
if (wait_for_partner(pipe, &pipe->w_counter)) |
|
goto err_rd; |
|
} |
|
} |
|
break; |
|
|
|
case FMODE_WRITE: |
|
/* |
|
* O_WRONLY |
|
* POSIX.1 says that O_NONBLOCK means return -1 with |
|
* errno=ENXIO when there is no process reading the FIFO. |
|
*/ |
|
ret = -ENXIO; |
|
if (!is_pipe && (filp->f_flags & O_NONBLOCK) && !pipe->readers) |
|
goto err; |
|
|
|
pipe->w_counter++; |
|
if (!pipe->writers++) |
|
wake_up_partner(pipe); |
|
|
|
if (!is_pipe && !pipe->readers) { |
|
if (wait_for_partner(pipe, &pipe->r_counter)) |
|
goto err_wr; |
|
} |
|
break; |
|
|
|
case FMODE_READ | FMODE_WRITE: |
|
/* |
|
* O_RDWR |
|
* POSIX.1 leaves this case "undefined" when O_NONBLOCK is set. |
|
* This implementation will NEVER block on a O_RDWR open, since |
|
* the process can at least talk to itself. |
|
*/ |
|
|
|
pipe->readers++; |
|
pipe->writers++; |
|
pipe->r_counter++; |
|
pipe->w_counter++; |
|
if (pipe->readers == 1 || pipe->writers == 1) |
|
wake_up_partner(pipe); |
|
break; |
|
|
|
default: |
|
ret = -EINVAL; |
|
goto err; |
|
} |
|
|
|
/* Ok! */ |
|
__pipe_unlock(pipe); |
|
return 0; |
|
|
|
err_rd: |
|
if (!--pipe->readers) |
|
wake_up_interruptible(&pipe->wr_wait); |
|
ret = -ERESTARTSYS; |
|
goto err; |
|
|
|
err_wr: |
|
if (!--pipe->writers) |
|
wake_up_interruptible_all(&pipe->rd_wait); |
|
ret = -ERESTARTSYS; |
|
goto err; |
|
|
|
err: |
|
__pipe_unlock(pipe); |
|
|
|
put_pipe_info(inode, pipe); |
|
return ret; |
|
} |
|
|
|
const struct file_operations pipefifo_fops = { |
|
.open = fifo_open, |
|
.llseek = no_llseek, |
|
.read_iter = pipe_read, |
|
.write_iter = pipe_write, |
|
.poll = pipe_poll, |
|
.unlocked_ioctl = pipe_ioctl, |
|
.release = pipe_release, |
|
.fasync = pipe_fasync, |
|
.splice_write = iter_file_splice_write, |
|
}; |
|
|
|
/* |
|
* Currently we rely on the pipe array holding a power-of-2 number |
|
* of pages. Returns 0 on error. |
|
*/ |
|
unsigned int round_pipe_size(unsigned long size) |
|
{ |
|
if (size > (1U << 31)) |
|
return 0; |
|
|
|
/* Minimum pipe size, as required by POSIX */ |
|
if (size < PAGE_SIZE) |
|
return PAGE_SIZE; |
|
|
|
return roundup_pow_of_two(size); |
|
} |
|
|
|
/* |
|
* Resize the pipe ring to a number of slots. |
|
* |
|
* Note the pipe can be reduced in capacity, but only if the current |
|
* occupancy doesn't exceed nr_slots; if it does, EBUSY will be |
|
* returned instead. |
|
*/ |
|
int pipe_resize_ring(struct pipe_inode_info *pipe, unsigned int nr_slots) |
|
{ |
|
struct pipe_buffer *bufs; |
|
unsigned int head, tail, mask, n; |
|
|
|
bufs = kcalloc(nr_slots, sizeof(*bufs), |
|
GFP_KERNEL_ACCOUNT | __GFP_NOWARN); |
|
if (unlikely(!bufs)) |
|
return -ENOMEM; |
|
|
|
spin_lock_irq(&pipe->rd_wait.lock); |
|
mask = pipe->ring_size - 1; |
|
head = pipe->head; |
|
tail = pipe->tail; |
|
|
|
n = pipe_occupancy(head, tail); |
|
if (nr_slots < n) { |
|
spin_unlock_irq(&pipe->rd_wait.lock); |
|
kfree(bufs); |
|
return -EBUSY; |
|
} |
|
|
|
/* |
|
* The pipe array wraps around, so just start the new one at zero |
|
* and adjust the indices. |
|
*/ |
|
if (n > 0) { |
|
unsigned int h = head & mask; |
|
unsigned int t = tail & mask; |
|
if (h > t) { |
|
memcpy(bufs, pipe->bufs + t, |
|
n * sizeof(struct pipe_buffer)); |
|
} else { |
|
unsigned int tsize = pipe->ring_size - t; |
|
if (h > 0) |
|
memcpy(bufs + tsize, pipe->bufs, |
|
h * sizeof(struct pipe_buffer)); |
|
memcpy(bufs, pipe->bufs + t, |
|
tsize * sizeof(struct pipe_buffer)); |
|
} |
|
} |
|
|
|
head = n; |
|
tail = 0; |
|
|
|
kfree(pipe->bufs); |
|
pipe->bufs = bufs; |
|
pipe->ring_size = nr_slots; |
|
if (pipe->max_usage > nr_slots) |
|
pipe->max_usage = nr_slots; |
|
pipe->tail = tail; |
|
pipe->head = head; |
|
|
|
spin_unlock_irq(&pipe->rd_wait.lock); |
|
|
|
/* This might have made more room for writers */ |
|
wake_up_interruptible(&pipe->wr_wait); |
|
return 0; |
|
} |
|
|
|
/* |
|
* Allocate a new array of pipe buffers and copy the info over. Returns the |
|
* pipe size if successful, or return -ERROR on error. |
|
*/ |
|
static long pipe_set_size(struct pipe_inode_info *pipe, unsigned long arg) |
|
{ |
|
unsigned long user_bufs; |
|
unsigned int nr_slots, size; |
|
long ret = 0; |
|
|
|
#ifdef CONFIG_WATCH_QUEUE |
|
if (pipe->watch_queue) |
|
return -EBUSY; |
|
#endif |
|
|
|
size = round_pipe_size(arg); |
|
nr_slots = size >> PAGE_SHIFT; |
|
|
|
if (!nr_slots) |
|
return -EINVAL; |
|
|
|
/* |
|
* If trying to increase the pipe capacity, check that an |
|
* unprivileged user is not trying to exceed various limits |
|
* (soft limit check here, hard limit check just below). |
|
* Decreasing the pipe capacity is always permitted, even |
|
* if the user is currently over a limit. |
|
*/ |
|
if (nr_slots > pipe->max_usage && |
|
size > pipe_max_size && !capable(CAP_SYS_RESOURCE)) |
|
return -EPERM; |
|
|
|
user_bufs = account_pipe_buffers(pipe->user, pipe->nr_accounted, nr_slots); |
|
|
|
if (nr_slots > pipe->max_usage && |
|
(too_many_pipe_buffers_hard(user_bufs) || |
|
too_many_pipe_buffers_soft(user_bufs)) && |
|
pipe_is_unprivileged_user()) { |
|
ret = -EPERM; |
|
goto out_revert_acct; |
|
} |
|
|
|
ret = pipe_resize_ring(pipe, nr_slots); |
|
if (ret < 0) |
|
goto out_revert_acct; |
|
|
|
pipe->max_usage = nr_slots; |
|
pipe->nr_accounted = nr_slots; |
|
return pipe->max_usage * PAGE_SIZE; |
|
|
|
out_revert_acct: |
|
(void) account_pipe_buffers(pipe->user, nr_slots, pipe->nr_accounted); |
|
return ret; |
|
} |
|
|
|
/* |
|
* Note that i_pipe and i_cdev share the same location, so checking ->i_pipe is |
|
* not enough to verify that this is a pipe. |
|
*/ |
|
struct pipe_inode_info *get_pipe_info(struct file *file, bool for_splice) |
|
{ |
|
struct pipe_inode_info *pipe = file->private_data; |
|
|
|
if (file->f_op != &pipefifo_fops || !pipe) |
|
return NULL; |
|
#ifdef CONFIG_WATCH_QUEUE |
|
if (for_splice && pipe->watch_queue) |
|
return NULL; |
|
#endif |
|
return pipe; |
|
} |
|
|
|
long pipe_fcntl(struct file *file, unsigned int cmd, unsigned long arg) |
|
{ |
|
struct pipe_inode_info *pipe; |
|
long ret; |
|
|
|
pipe = get_pipe_info(file, false); |
|
if (!pipe) |
|
return -EBADF; |
|
|
|
__pipe_lock(pipe); |
|
|
|
switch (cmd) { |
|
case F_SETPIPE_SZ: |
|
ret = pipe_set_size(pipe, arg); |
|
break; |
|
case F_GETPIPE_SZ: |
|
ret = pipe->max_usage * PAGE_SIZE; |
|
break; |
|
default: |
|
ret = -EINVAL; |
|
break; |
|
} |
|
|
|
__pipe_unlock(pipe); |
|
return ret; |
|
} |
|
|
|
static const struct super_operations pipefs_ops = { |
|
.destroy_inode = free_inode_nonrcu, |
|
.statfs = simple_statfs, |
|
}; |
|
|
|
/* |
|
* pipefs should _never_ be mounted by userland - too much of security hassle, |
|
* no real gain from having the whole whorehouse mounted. So we don't need |
|
* any operations on the root directory. However, we need a non-trivial |
|
* d_name - pipe: will go nicely and kill the special-casing in procfs. |
|
*/ |
|
|
|
static int pipefs_init_fs_context(struct fs_context *fc) |
|
{ |
|
struct pseudo_fs_context *ctx = init_pseudo(fc, PIPEFS_MAGIC); |
|
if (!ctx) |
|
return -ENOMEM; |
|
ctx->ops = &pipefs_ops; |
|
ctx->dops = &pipefs_dentry_operations; |
|
return 0; |
|
} |
|
|
|
static struct file_system_type pipe_fs_type = { |
|
.name = "pipefs", |
|
.init_fs_context = pipefs_init_fs_context, |
|
.kill_sb = kill_anon_super, |
|
}; |
|
|
|
#ifdef CONFIG_SYSCTL |
|
static int do_proc_dopipe_max_size_conv(unsigned long *lvalp, |
|
unsigned int *valp, |
|
int write, void *data) |
|
{ |
|
if (write) { |
|
unsigned int val; |
|
|
|
val = round_pipe_size(*lvalp); |
|
if (val == 0) |
|
return -EINVAL; |
|
|
|
*valp = val; |
|
} else { |
|
unsigned int val = *valp; |
|
*lvalp = (unsigned long) val; |
|
} |
|
|
|
return 0; |
|
} |
|
|
|
static int proc_dopipe_max_size(struct ctl_table *table, int write, |
|
void *buffer, size_t *lenp, loff_t *ppos) |
|
{ |
|
return do_proc_douintvec(table, write, buffer, lenp, ppos, |
|
do_proc_dopipe_max_size_conv, NULL); |
|
} |
|
|
|
static struct ctl_table fs_pipe_sysctls[] = { |
|
{ |
|
.procname = "pipe-max-size", |
|
.data = &pipe_max_size, |
|
.maxlen = sizeof(pipe_max_size), |
|
.mode = 0644, |
|
.proc_handler = proc_dopipe_max_size, |
|
}, |
|
{ |
|
.procname = "pipe-user-pages-hard", |
|
.data = &pipe_user_pages_hard, |
|
.maxlen = sizeof(pipe_user_pages_hard), |
|
.mode = 0644, |
|
.proc_handler = proc_doulongvec_minmax, |
|
}, |
|
{ |
|
.procname = "pipe-user-pages-soft", |
|
.data = &pipe_user_pages_soft, |
|
.maxlen = sizeof(pipe_user_pages_soft), |
|
.mode = 0644, |
|
.proc_handler = proc_doulongvec_minmax, |
|
}, |
|
{ } |
|
}; |
|
#endif |
|
|
|
static int __init init_pipe_fs(void) |
|
{ |
|
int err = register_filesystem(&pipe_fs_type); |
|
|
|
if (!err) { |
|
pipe_mnt = kern_mount(&pipe_fs_type); |
|
if (IS_ERR(pipe_mnt)) { |
|
err = PTR_ERR(pipe_mnt); |
|
unregister_filesystem(&pipe_fs_type); |
|
} |
|
} |
|
#ifdef CONFIG_SYSCTL |
|
register_sysctl_init("fs", fs_pipe_sysctls); |
|
#endif |
|
return err; |
|
} |
|
|
|
fs_initcall(init_pipe_fs);
|
|
|