Re: [PATCH v2 5/6] blk-mq: fix freeze queue race

[Tejun Heo]

On Thu, Jul 09, 2015 at 02:55:10PM +0800, Ming Lei wrote:
> This patch looks fine since at least changing DEAD state of percpu ref
> state should have been synchronized by caller.
> 
> Also looks __percpu_ref_switch_to_percpu() need to check if the refcount
> becomes dead after current switching, and seems something like following
> is needed:

Hmmm... but the caller is responsible for synchronization for these
operations.  If the state changes while waiting, it indicates a
synchronization bug and testing it one more time is kinda weird.  What
if it changes right after that test?

Thanks.

-- 
tejun
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