Re: [Xen-devel] [PATCH 2/2] smp: convert cpu_hotplug_begin into a blocking lock acquisition

[Jan Beulich <jbeulich@xxxxxxxx>]

On 13.02.2020 12:32, Roger Pau Monne wrote:
> Don't allow cpu_hotplug_begin to fail by converting the trylock into a
> blocking lock acquisition. Write users of the cpu_add_remove_lock are
> limited to CPU plug/unplug operations, and cannot deadlock between
> themselves or other users taking the lock in read mode as
> cpu_add_remove_lock is always locked with interrupts enabled. There
> are also no other locks taken during the plug/unplug operations.

I don't think the goal was deadlock avoidance, but rather limiting
of the time spent spinning while trying to acquire the lock, in
favor of having the caller retry.

Jan

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