From: Andrew Morton <akpm@linux-foundation.org>
To: Benjamin Segall <bsegall@google.com>
Cc: Christian Brauner <brauner@kernel.org>,
Eric Biggers <ebiggers@kernel.org>,
Alexander Viro <viro@zeniv.linux.org.uk>,
linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
stable@vger.kernel.org
Subject: Re: [PATCH RESEND] epoll: ep_autoremove_wake_function should use list_del_init_careful
Date: Wed, 31 May 2023 15:26:35 -0700 [thread overview]
Message-ID: <20230531152635.e8bb796bee235977c141138c@linux-foundation.org> (raw)
In-Reply-To: <xm26ilc8uoz6.fsf@google.com>
On Wed, 31 May 2023 15:15:41 -0700 Benjamin Segall <bsegall@google.com> wrote:
> >> Can you please provide a more detailed explanation about why
> >> list_del_init_careful() is needed here?
> >
> > Yeah, this needs more explanation... Next time someone looks at this
> > code and there's a *_careful() added they'll want to know why.
>
> So the general reason is the same as with autoremove_wake_function, it
> pairs with the list_entry_careful in ep_poll (which is epoll's modified
> copy of finish_wait).
>
> I think the original actual _problem_ was a -stable issue that was fixed
> instead by doing additional backports, so this may just avoid potential
> extra loops and avoid potential compiler shenanigans from the data race.
The point is that the foo_careful() callsites should be commented, please.
next prev parent reply other threads:[~2023-05-31 22:26 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-30 18:32 Benjamin Segall
2023-05-31 1:57 ` Eric Biggers
2023-05-31 7:53 ` Christian Brauner
2023-05-31 22:15 ` Benjamin Segall
2023-05-31 22:26 ` Andrew Morton [this message]
2023-05-31 23:24 ` [PATCH v2] " Benjamin Segall
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