linux-kernel - Re: [PATCH] pipe_read: don't wake up the writer if the pipe is still full

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Message-ID: <20250104-lauwarm-beide-c6be67c9b682@brauner>
Date: Sat,  4 Jan 2025 09:42:31 +0100
From: Christian Brauner <brauner@...nel.org>
To: Oleg Nesterov <oleg@...hat.com>
Cc: Christian Brauner <brauner@...nel.org>,
	WangYuli <wangyuli@...ontech.com>,
	linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Manfred Spraul <manfred@...orfullife.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	David Howells <dhowells@...hat.com>
Subject: Re: [PATCH] pipe_read: don't wake up the writer if the pipe is still full

On Thu, 02 Jan 2025 15:07:15 +0100, Oleg Nesterov wrote:
> wake_up(pipe->wr_wait) makes no sense if pipe_full() is still true after
> the reading, the writer sleeping in wait_event(wr_wait, pipe_writable())
> will check the pipe_writable() == !pipe_full() condition and sleep again.
> 
> Only wake the writer if we actually released a pipe buf, and the pipe was
> full before we did so.
> 
> [...]

Applied to the vfs-6.14.misc branch of the vfs/vfs.git tree.
Patches in the vfs-6.14.misc branch should appear in linux-next soon.

Please report any outstanding bugs that were missed during review in a
new review to the original patch series allowing us to drop it.

It's encouraged to provide Acked-bys and Reviewed-bys even though the
patch has now been applied. If possible patch trailers will be updated.

Note that commit hashes shown below are subject to change due to rebase,
trailer updates or similar. If in doubt, please check the listed branch.

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs.git
branch: vfs-6.14.misc

[1/1] pipe_read: don't wake up the writer if the pipe is still full
      https://git.kernel.org/vfs/vfs/c/b004b4d254e7