Re: [PATCH v2 13/52] sparc, sysfs: Fix CPU hotplug callback registration

From: David Miller
Date: Fri Feb 14 2014 - 13:31:07 EST


From: "Srivatsa S. Bhat" <srivatsa.bhat@xxxxxxxxxxxxxxxxxx>
Date: Fri, 14 Feb 2014 13:22:05 +0530

> Subsystems that want to register CPU hotplug callbacks, as well as perform
> initialization for the CPUs that are already online, often do it as shown
> below:
...
> This is wrong, since it is prone to ABBA deadlocks involving the
> cpu_add_remove_lock and the cpu_hotplug.lock (when running concurrently
> with CPU hotplug operations).
>
> Instead, the correct and race-free way of performing the callback
> registration is:
...
> Fix the sysfs code in sparc by using this latter form of callback
> registration.
>
> Cc: "David S. Miller" <davem@xxxxxxxxxxxxx>
> Cc: Ingo Molnar <mingo@xxxxxxxxxx>
> Cc: sparclinux@xxxxxxxxxxxxxxx
> Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@xxxxxxxxxxxxxxxxxx>

Acked-by: David S. Miller <davem@xxxxxxxxxxxxx>
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