Date:   Mon, 27 Feb 2023 16:43:59 +0100
From:   Peter Zijlstra <peterz@infradead.org>
To:     Steven Rostedt <rostedt@goodmis.org>
Cc:     Schspa Shi <schspa@gmail.com>, linux-kernel@vger.kernel.org,
        cocci@inria.fr, mcgrof@kernel.org,
        Julia Lawall <Julia.Lawall@inria.fr>,
        Nicolas Palix <nicolas.palix@imag.fr>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@collabora.com>,
        Ingo Molnar <mingo@redhat.com>,
        Juri Lelli <juri.lelli@redhat.com>,
        Vincent Guittot <vincent.guittot@linaro.org>,
        Dietmar Eggemann <dietmar.eggemann@arm.com>,
        Ben Segall <bsegall@google.com>, Mel Gorman <mgorman@suse.de>,
        Daniel Bristot de Oliveira <bristot@redhat.com>,
        Valentin Schneider <vschneid@redhat.com>,
        buytenh@wantstofly.org, johannes.berg@intel.com,
        gregkh@linuxfoundation.org, tomba@kernel.org, airlied@gmail.com,
        daniel@ffwll.ch
Subject: Re: [RFC PATCH] cocci: cpi: add complete api check script
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On Mon, Feb 27, 2023 at 10:28:08AM -0500, Steven Rostedt wrote:

> So what exact race are you trying to catch here?

on-stack copmletion with a wait_for_completion that can return early
(eg. killable, interruptible, or timeout) can go out of scope (eg, free
the completion) with the other side calling complete() on some possibly
re-used piece of stack.

IOW, Use-after-Free.

Care must be taken to ensure the other side (whatever does complete())
is either terminated or otherwise stopped from calling complete() on an
out-of-scope variable.