From: Qian Cai <cai@lca.pw>
To: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>,
Marco Elver <elver@google.com>,
Linux PM <linux-pm@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH -next] power/qos: fix a data race in pm_qos_*_value
Date: Tue, 25 Feb 2020 19:34:18 -0500 [thread overview]
Message-ID: <705D8B35-FBB5-4D32-AE63-DD4E773CEC1E@lca.pw> (raw)
In-Reply-To: <CAJZ5v0jDjK63R4kbBb_aU7ZBXbCG_vfOW33aVBRbYV7hEOWYqA@mail.gmail.com>
> On Feb 25, 2020, at 7:10 PM, Rafael J. Wysocki <rafael@kernel.org> wrote:
>
> The target_value field in struct pm_qos_constraints is used for
> lockless access to the effective constraint value of a given QoS list,
> so the readers of it cannot expect it to always reflect the most
> recent effective constraint value. However, they can and do expect it
> to be equal to a valid effective constraint value computed at a
> certain time in the past (event though it may not be the most recent
> one), so add READ|WRITE_ONCE() annotations around the target_value
> accesses to prevent the compiler from possibly causing that
> expectation to be unmet by generating code in an exceptionally
> convoluted way.
Perfect. I’ll send a v2 for that unless you would like to squash it in.
prev parent reply other threads:[~2020-02-26 0:34 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-21 21:09 [PATCH -next] power/qos: fix a data race in pm_qos_*_value Qian Cai
2020-02-24 0:12 ` Rafael J. Wysocki
2020-02-24 1:01 ` Qian Cai
2020-02-24 9:54 ` Rafael J. Wysocki
2020-02-24 19:02 ` Qian Cai
2020-02-26 0:10 ` Rafael J. Wysocki
2020-02-26 0:34 ` Qian Cai [this message]
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