Commit 9c87bcf0 authored by Michael Kerrisk (man-pages)'s avatar Michael Kerrisk (man-pages) Committed by Linus Torvalds
Browse files

pipe: make account_pipe_buffers() return a value, and use it 

This is an optional patch, to provide a small performance
improvement.  Alter account_pipe_buffers() so that it returns the
new value in user->pipe_bufs. This means that we can refactor
too_many_pipe_buffers_soft() and too_many_pipe_buffers_hard() to
avoid the costs of repeated use of atomic_long_read() to get the
value user->pipe_bufs.

Link: http://lkml.kernel.org/r/93e5f193-1e5e-3e1f-3a20-eae79b7e1310@gmail.com


Signed-off-by: default avatarMichael Kerrisk <mtk.manpages@gmail.com>
Reviewed-by: default avatarVegard Nossum <vegard.nossum@oracle.com>
Cc: Willy Tarreau <w@1wt.eu>
Cc: <socketpair@gmail.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Jens Axboe <axboe@fb.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent a005ca0e

fs/pipe.c

+18 −18
Original line number Diff line number Diff line
@@ -601,22 +601,20 @@ pipe_fasync(int fd, struct file *filp, int on) 
	return retval;

}



static void account_pipe_buffers(struct user_struct *user,

static unsigned long account_pipe_buffers(struct user_struct *user,

                                 unsigned long old, unsigned long new)

{

	atomic_long_add(new - old, &user->pipe_bufs);

	return atomic_long_add_return(new - old, &user->pipe_bufs);

}



static bool too_many_pipe_buffers_soft(struct user_struct *user)

static bool too_many_pipe_buffers_soft(unsigned long user_bufs)

{

	return pipe_user_pages_soft &&

	       atomic_long_read(&user->pipe_bufs) >= pipe_user_pages_soft;

	return pipe_user_pages_soft && user_bufs >= pipe_user_pages_soft;

}



static bool too_many_pipe_buffers_hard(struct user_struct *user)

static bool too_many_pipe_buffers_hard(unsigned long user_bufs)

{

	return pipe_user_pages_hard &&

	       atomic_long_read(&user->pipe_bufs) >= pipe_user_pages_hard;

	return pipe_user_pages_hard && user_bufs >= pipe_user_pages_hard;

}



struct pipe_inode_info *alloc_pipe_info(void)
@@ -624,19 +622,20 @@ 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;



	pipe = kzalloc(sizeof(struct pipe_inode_info), GFP_KERNEL_ACCOUNT);

	if (pipe == NULL)

		goto out_free_uid;



	account_pipe_buffers(user, 0, pipe_bufs);

	user_bufs = account_pipe_buffers(user, 0, pipe_bufs);



	if (too_many_pipe_buffers_soft(user)) {

		account_pipe_buffers(user, pipe_bufs, 1);

	if (too_many_pipe_buffers_soft(user_bufs)) {

		user_bufs = account_pipe_buffers(user, pipe_bufs, 1);

		pipe_bufs = 1;

	}



	if (too_many_pipe_buffers_hard(user))

	if (too_many_pipe_buffers_hard(user_bufs))

		goto out_revert_acct;



	pipe->bufs = kcalloc(pipe_bufs, sizeof(struct pipe_buffer),
@@ -652,7 +651,7 @@ struct pipe_inode_info *alloc_pipe_info(void) 
	}



out_revert_acct:

	account_pipe_buffers(user, pipe_bufs, 0);

	(void) account_pipe_buffers(user, pipe_bufs, 0);

	kfree(pipe);

out_free_uid:

	free_uid(user);
@@ -663,7 +662,7 @@ void free_pipe_info(struct pipe_inode_info *pipe) 
{

	int i;



	account_pipe_buffers(pipe->user, pipe->buffers, 0);

	(void) account_pipe_buffers(pipe->user, pipe->buffers, 0);

	free_uid(pipe->user);

	for (i = 0; i < pipe->buffers; i++) {

		struct pipe_buffer *buf = pipe->bufs + i;
@@ -1034,6 +1033,7 @@ static long pipe_set_size(struct pipe_inode_info *pipe, unsigned long arg) 
{

	struct pipe_buffer *bufs;

	unsigned int size, nr_pages;

	unsigned long user_bufs;

	long ret = 0;



	size = round_pipe_size(arg);
@@ -1053,11 +1053,11 @@ static long pipe_set_size(struct pipe_inode_info *pipe, unsigned long arg) 
			size > pipe_max_size && !capable(CAP_SYS_RESOURCE))

		return -EPERM;



	account_pipe_buffers(pipe->user, pipe->buffers, nr_pages);

	user_bufs = account_pipe_buffers(pipe->user, pipe->buffers, nr_pages);



	if (nr_pages > pipe->buffers &&

			(too_many_pipe_buffers_hard(pipe->user) ||

			 too_many_pipe_buffers_soft(pipe->user)) &&

			(too_many_pipe_buffers_hard(user_bufs) ||

			 too_many_pipe_buffers_soft(user_bufs)) &&

			!capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN)) {

		ret = -EPERM;

		goto out_revert_acct;
@@ -1109,7 +1109,7 @@ static long pipe_set_size(struct pipe_inode_info *pipe, unsigned long arg) 
	return nr_pages * PAGE_SIZE;



out_revert_acct:

	account_pipe_buffers(pipe->user, nr_pages, pipe->buffers);

	(void) account_pipe_buffers(pipe->user, nr_pages, pipe->buffers);

	return ret;

}

CRA Git | Maintained and supported by SUSTech CRA and CCSE