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rescounters: add res_counter_uncharge_until()

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When killing a res_counter which is a child of other counter, we need to
do

	res_counter_uncharge(child, xxx)
	res_counter_charge(parent, xxx)

This is not atomic and wastes CPU.  This patch adds
res_counter_uncharge_until().  This function's uncharge propagates to
ancestors until specified res_counter.

	res_counter_uncharge_until(child, parent, xxx)

Now the operation is atomic and efficient.

Signed-off-by: Frederic Weisbecker <fweisbec@redhat.com>
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Ying Han <yinghan@google.com>
Cc: Glauber Costa <glommer@parallels.com>
Reviewed-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Frederic Weisbecker
2012-05-29 15:07:03 -07:00
committed by Linus Torvalds
parent f9be23d6da
commit 2bb2ba9d51
3 changed files with 19 additions and 2 deletions
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3
include/linux/res_counter.h
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@@ -135,6 +135,9 @@ int __must_check res_counter_charge_nofail(struct res_counter *counter,
void res_counter_uncharge_locked(struct res_counter *counter, unsigned long val);
void res_counter_uncharge(struct res_counter *counter, unsigned long val);
void res_counter_uncharge_until(struct res_counter *counter,
struct res_counter *top,
unsigned long val);
/**
* res_counter_margin - calculate chargeable space of a counter
* @cnt: the counter