From: Max Kellermann <max.kellermann@ionos.com>
To: Christian Brauner <brauner@kernel.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>
Subject: Re: When to lock pipe->rd_wait.lock?
Date: Thu, 21 Sep 2023 09:28:13 +0200 [thread overview]
Message-ID: <CAKPOu+_Ebj6-YXPd4HWqG7TokZDvw26uM4xuJGL7k0gg+tHeyw@mail.gmail.com> (raw)
In-Reply-To: <20230920-macht-rupfen-96240ce98330@brauner>
On Wed, Sep 20, 2023 at 3:30 PM Christian Brauner <brauner@kernel.org> wrote:
> Afaict, the mutex is sufficient protection unless you're using
> watchqueues which use post_one_notification() that cannot acquire the
> pipe mutex. Since splice operations aren't supported on such kernel
> notification pipes - see get_pipe_info() - it should be unproblematic.
I had another look at this, and something's fishy with the code or
with your explanation (or I still don't get it). If there is a
watch_queue, pipe_write() fails early with EXDEV - writing to such a
pipe is simply forbidden, the code is not reachable in the presence of
a watch_queue, therefore locking just because there might be a
wait_queue does not appear to make sense?
next prev parent reply other threads:[~2023-09-21 18:50 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-09-20 12:34 When to lock pipe->rd_wait.lock? Max Kellermann
2023-09-20 13:30 ` Christian Brauner
2023-09-20 15:21 ` Max Kellermann
2023-09-20 15:50 ` Christian Brauner
2023-09-20 16:14 ` Max Kellermann
2023-09-21 7:28 ` Max Kellermann [this message]
2023-09-21 8:05 ` Max Kellermann
2023-09-21 9:17 ` Christian Brauner
2023-09-21 9:38 ` Max Kellermann
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