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Re: [PATCH v5 08/14] res_counter: return amount of charges after res_counter_uncharge [message #48449 is a reply to message #48392] Wed, 17 October 2012 23:23 Go to previous message
David Rientjes is currently offline  David Rientjes
Messages: 59
Registered: November 2006
Member
On Tue, 16 Oct 2012, Glauber Costa wrote:

> It is useful to know how many charges are still left after a call to
> res_counter_uncharge. While it is possible to issue a res_counter_read
> after uncharge, this can be racy.
>
> If we need, for instance, to take some action when the counters drop
> down to 0, only one of the callers should see it. This is the same
> semantics as the atomic variables in the kernel.
>
> Since the current return value is void, we don't need to worry about
> anything breaking due to this change: nobody relied on that, and only
> users appearing from now on will be checking this value.
>
> Signed-off-by: Glauber Costa <glommer@parallels.com>
> Reviewed-by: Michal Hocko <mhocko@suse.cz>
> Acked-by: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
> CC: Johannes Weiner <hannes@cmpxchg.org>
> CC: Suleiman Souhlal <suleiman@google.com>
> CC: Tejun Heo <tj@kernel.org>

Acked-by: David Rientjes <rientjes@google.com>

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