linux-kernel - Re: [PATCH 3/4 V2] Use get_online_cpus to avoid races involving CPU hotplug

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Message-ID: <20120804105216.476f5513@endymion.delvare>
Date:	Sat, 4 Aug 2012 10:52:16 +0200
From:	Jean Delvare <khali@...ux-fr.org>
To:	Silas Boyd-Wickizer <sbw@....edu>
Cc:	linux-kernel@...r.kernel.org,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	Guenter Roeck <linux@...ck-us.net>,
	Thomas Gleixner <tglx@...utronix.de>,
	Harald Welte <laforge@...nezx.org>, x86@...nel.org
Subject: Re: [PATCH 3/4 V2] Use get_online_cpus to avoid races involving CPU
  hotplug

On Fri, 3 Aug 2012 12:35:28 -0700, Silas Boyd-Wickizer wrote:
> via_cputemp_init in drivers/hwmon/via-cputemp.c loops with
> for_each_online_cpu, adding platform_devices, then calls
> register_hotcpu_notifier.  If a CPU is offlined between the loop and
> register_hotcpu_notifier, then later onlined, via_cputemp_device_add
> will attempt to add platform devices with the same ID.  A similar race
> occurs during via_cputemp_exit, after the module calls
> unregister_hotcpu_notifier, a CPU might offline and a device will
> exist for a CPU that is offline.
> 
> This fix surrounds for_each_online_cpu and register_hotcpu_notifier
> with get_online_cpus+put_online_cpus; and surrounds
> unregister_hotcpu_notifier and device unregistering with
> get_online_cpus+put_online_cpus.
> 
> Build tested.
> 
> Signed-off-by: Silas Boyd-Wickizer <sbw@....edu>
> ---
>  drivers/hwmon/via-cputemp.c |    5 +++++
>  1 file changed, 5 insertions(+)
> (...)

Applied, thanks.

-- 
Jean Delvare
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