linux-kernel - Re: [PATCH 5.0 047/246] fs: Make splice() and tee() take into account O

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Date:   Thu, 4 Apr 2019 16:16:57 +0000
From:   Slavomir Kaslev <kaslevs@...are.com>
To:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>
CC:     "torvalds@...ux-foundation.org" <torvalds@...ux-foundation.org>,
        "sashal@...nel.org" <sashal@...nel.org>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>,
        "rostedt@...dmis.org" <rostedt@...dmis.org>
Subject: Re: [PATCH 5.0 047/246] fs: Make splice() and tee() take into account
 O_NONBLOCK flag on pipes

On Thu, 2019-04-04 at 10:45 +0200, Greg Kroah-Hartman wrote:
> 5.0-stable review patch.  If anyone has any objections, please let me
> know.
> 
> ------------------
> 
> [ Upstream commit ee5e001196d1345b8fee25925ff5f1d67936081e ]
> 
> The current implementation of splice() and tee() ignores O_NONBLOCK
> set
> on pipe file descriptors and checks only the SPLICE_F_NONBLOCK flag
> for
> blocking on pipe arguments.  This is inconsistent since splice()-ing
> from/to non-pipe file descriptors does take O_NONBLOCK into
> consideration.
> 
> Fix this by promoting O_NONBLOCK, when set on a pipe, to
> SPLICE_F_NONBLOCK.

[...]

> This change does have potential of breaking users who don't expect
> EAGAIN from splice() when SPLICE_F_NONBLOCK is not set.  OTOH
> programs
> that set O_NONBLOCK and don't anticipate EAGAIN are arguably
> buggy[2].

Hi Greg,

Can you drop this one from the stable queues? We discussed it with
Sasha[1] already in the autosel patches thread.

[1] https://lkml.org/lkml/2019/4/3/811

-- Slavi