Re: [PATCH v4 08/14] res_counter: return amount of charges after res_counter_uncharge

Kamezawa Hiroyuki
2012-10-16T08:21:24Z

(2012/10/08 19:06), 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>
> CC: Michal Hocko <mhocko@suse.cz>
> CC: Johannes Weiner <hannes@cmpxchg.org>
> CC: Suleiman Souhlal <suleiman@google.com>
> CC: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
> ---
> Documentation/cgroups/resource_counter.txt | 7 ++++---
> include/linux/res_counter.h | 12 +++++++-----
> kernel/res_counter.c | 20 +++++++++++++-------
> 3 files changed, 24 insertions(+), 15 deletions(-)

Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>