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3d742d4b6e
Delete duplicate words in fs/*.c. The doubled words that are being dropped are: that, be, the, in, and, for Link: https://lkml.kernel.org/r/20201224052810.25315-1-rdunlap@infradead.org Signed-off-by: Randy Dunlap <rdunlap@infradead.org> Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1432 lines
34 KiB
C
1432 lines
34 KiB
C
// 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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#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/uaccess.h>
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#include <asm/ioctls.h>
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#include "internal.h"
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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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unsigned int pipe_max_size = 1048576;
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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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unsigned long pipe_user_pages_hard;
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unsigned long pipe_user_pages_soft = PIPE_DEF_BUFFERS * INR_OPEN_CUR;
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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 <jelson@circlemud.org> 2001-08-16
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*
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* pipe_read & write cleanup
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* -- Manfred Spraul <manfred@colorfullife.com> 2002-05-09
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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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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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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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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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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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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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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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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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* 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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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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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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* 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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* 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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* 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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* 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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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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/* 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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return !pipe_empty(head, tail) || !writers;
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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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/* Null read succeeds. */
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if (unlikely(total_len == 0))
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return 0;
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ret = 0;
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__pipe_lock(pipe);
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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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unsigned int head = 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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#ifdef CONFIG_WATCH_QUEUE
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if (pipe->note_loss) {
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struct watch_notification n;
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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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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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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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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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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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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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/* 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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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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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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* 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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}
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/*
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* But because we didn't read anything, at this point we can
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* just return directly with -ERESTARTSYS if we're interrupted,
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* 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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kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT);
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}
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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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if (ret > 0)
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file_accessed(filp);
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return ret;
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}
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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() */
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static inline bool pipe_writable(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 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);
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}
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static ssize_t
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pipe_write(struct kiocb *iocb, struct iov_iter *from)
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{
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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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unsigned int head;
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ssize_t ret = 0;
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size_t total_len = iov_iter_count(from);
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ssize_t chars;
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bool was_empty = false;
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bool wake_next_writer = false;
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/* Null write succeeds. */
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if (unlikely(total_len == 0))
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return 0;
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__pipe_lock(pipe);
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if (!pipe->readers) {
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send_sig(SIGPIPE, current, 0);
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ret = -EPIPE;
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goto out;
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}
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#ifdef CONFIG_WATCH_QUEUE
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if (pipe->watch_queue) {
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ret = -EXDEV;
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goto out;
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}
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#endif
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/*
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* Only wake up if the pipe started out empty, since
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* otherwise there should be no readers waiting.
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*
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* If it wasn't empty we try to merge new data into
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* the last buffer.
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*
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* That naturally merges small writes, but it also
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* page-aligs the rest of the writes for large writes
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* spanning multiple pages.
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*/
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head = pipe->head;
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was_empty = pipe_empty(head, pipe->tail);
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chars = total_len & (PAGE_SIZE-1);
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if (chars && !was_empty) {
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unsigned int mask = pipe->ring_size - 1;
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struct pipe_buffer *buf = &pipe->bufs[(head - 1) & mask];
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int offset = buf->offset + buf->len;
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if ((buf->flags & PIPE_BUF_FLAG_CAN_MERGE) &&
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offset + chars <= PAGE_SIZE) {
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ret = pipe_buf_confirm(pipe, buf);
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if (ret)
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goto out;
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ret = copy_page_from_iter(buf->page, offset, chars, from);
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if (unlikely(ret < chars)) {
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ret = -EFAULT;
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goto out;
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}
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buf->len += ret;
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if (!iov_iter_count(from))
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goto out;
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}
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}
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for (;;) {
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if (!pipe->readers) {
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send_sig(SIGPIPE, current, 0);
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if (!ret)
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ret = -EPIPE;
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break;
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}
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head = pipe->head;
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if (!pipe_full(head, pipe->tail, pipe->max_usage)) {
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unsigned int mask = pipe->ring_size - 1;
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struct pipe_buffer *buf = &pipe->bufs[head & mask];
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struct page *page = pipe->tmp_page;
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int copied;
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|
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if (!page) {
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page = alloc_page(GFP_HIGHUSER | __GFP_ACCOUNT);
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if (unlikely(!page)) {
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ret = ret ? : -ENOMEM;
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break;
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}
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pipe->tmp_page = page;
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}
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|
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/* Allocate a slot in the ring in advance and attach an
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* empty buffer. If we fault or otherwise fail to use
|
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* it, either the reader will consume it or it'll still
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* be there for the next write.
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*/
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spin_lock_irq(&pipe->rd_wait.lock);
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head = pipe->head;
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if (pipe_full(head, pipe->tail, pipe->max_usage)) {
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spin_unlock_irq(&pipe->rd_wait.lock);
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continue;
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}
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pipe->head = head + 1;
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spin_unlock_irq(&pipe->rd_wait.lock);
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|
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/* Insert it into the buffer array */
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buf = &pipe->bufs[head & mask];
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buf->page = page;
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buf->ops = &anon_pipe_buf_ops;
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buf->offset = 0;
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buf->len = 0;
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if (is_packetized(filp))
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buf->flags = PIPE_BUF_FLAG_PACKET;
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else
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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
|
|
*/
|
|
if (was_empty) {
|
|
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;
|
|
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;
|
|
|
|
/*
|
|
* 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, 1);
|
|
pipe_bufs = 1;
|
|
}
|
|
|
|
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)
|
|
{
|
|
int i;
|
|
|
|
#ifdef CONFIG_WATCH_QUEUE
|
|
if (pipe->watch_queue) {
|
|
watch_queue_clear(pipe->watch_queue);
|
|
put_watch_queue(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);
|
|
}
|
|
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(dentry, 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.
|
|
*/
|
|
int pipe_resize_ring(struct pipe_inode_info *pipe, unsigned int nr_slots)
|
|
{
|
|
struct pipe_buffer *bufs;
|
|
unsigned int head, tail, mask, n;
|
|
|
|
/*
|
|
* We can shrink the pipe, if arg is greater than the ring occupancy.
|
|
* Since we don't expect a lot of shrink+grow operations, just free and
|
|
* allocate again like we would do for growing. If the pipe currently
|
|
* contains more buffers than arg, then return busy.
|
|
*/
|
|
mask = pipe->ring_size - 1;
|
|
head = pipe->head;
|
|
tail = pipe->tail;
|
|
n = pipe_occupancy(pipe->head, pipe->tail);
|
|
if (nr_slots < n)
|
|
return -EBUSY;
|
|
|
|
bufs = kcalloc(nr_slots, sizeof(*bufs),
|
|
GFP_KERNEL_ACCOUNT | __GFP_NOWARN);
|
|
if (unlikely(!bufs))
|
|
return -ENOMEM;
|
|
|
|
/*
|
|
* 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;
|
|
|
|
/* 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,
|
|
};
|
|
|
|
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);
|
|
}
|
|
}
|
|
return err;
|
|
}
|
|
|
|
fs_initcall(init_pipe_fs);
|