linux-kernel - Re: [PATCH AUTOSEL 4.9 20/87] fs: Make splice() and tee() take into account O

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Message-ID: <20190403161906.GD16241@sasha-vm>
Date:   Wed, 3 Apr 2019 12:19:06 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     Steven Rostedt <rostedt@...dmis.org>
Cc:     Slavomir Kaslev <kaslevs@...are.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>,
        "torvalds@...ux-foundation.org" <torvalds@...ux-foundation.org>,
        "linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>
Subject: Re: [PATCH AUTOSEL 4.9 20/87] fs: Make splice() and tee() take into
 account O_NONBLOCK flag on pipes

On Thu, Mar 28, 2019 at 12:04:17PM -0400, Steven Rostedt wrote:
>On Thu, 28 Mar 2019 15:37:49 +0000
>Slavomir Kaslev <kaslevs@...are.com> wrote:
>
>> On Wed, 2019-03-27 at 14:19 -0400, Sasha Levin wrote:
>> > From: Slavomir Kaslev <kaslevs@...are.com>
>> >
>> > [ 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.
>>
>> Hey Sasha,
>>
>> I don't think that this patch should be merged to stable kernels. It's
>> more of a feature rather than a bug/regression fix and it changes how
>> splice() has been working from day one.
>>
>> Can you please drop it from the stable queues?
>>
>
>On the other hand, it keeps stable more in sync with what mainline has.
>If someone writes new code against a stable release, and depends on
>this behavior, it's less likely to break when they run it on a newer
>kernel. Which means its less likely that Linus will revert your
>change ;-)

I'm going to drop this, I don't really want to take things which
knowingly might brake userspace.

--
Thanks,
Sasha