Commit 2bb2ba9d authored by Frederic Weisbecker's avatar Frederic Weisbecker Committed by Linus Torvalds
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rescounters: add res_counter_uncharge_until() 



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: default avatarFrederic Weisbecker <fweisbec@redhat.com>
Signed-off-by: default avatarKAMEZAWA 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: default avatarTejun Heo <tj@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent f9be23d6

Documentation/cgroups/resource_counter.txt

+8 −0
Original line number Diff line number Diff line
@@ -92,6 +92,14 @@ to work with it. 


	The _locked routines imply that the res_counter->lock is taken.



 f. void res_counter_uncharge_until

		(struct res_counter *rc, struct res_counter *top,

		 unsinged long val)



	Almost same as res_cunter_uncharge() but propagation of uncharge

	stops when rc == top. This is useful when kill a res_coutner in

	child cgroup.



 2.1 Other accounting routines



    There are more routines that may help you with common needs, like

include/linux/res_counter.h

+3 −0
Original line number Diff line number Diff line
@@ -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

kernel/res_counter.c

+8 −2
Original line number Diff line number Diff line
@@ -94,13 +94,15 @@ void res_counter_uncharge_locked(struct res_counter *counter, unsigned long val) 
	counter->usage -= 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)

{

	unsigned long flags;

	struct res_counter *c;



	local_irq_save(flags);

	for (c = counter; c != NULL; c = c->parent) {

	for (c = counter; c != top; c = c->parent) {

		spin_lock(&c->lock);

		res_counter_uncharge_locked(c, val);

		spin_unlock(&c->lock);
@@ -108,6 +110,10 @@ void res_counter_uncharge(struct res_counter *counter, unsigned long val) 
	local_irq_restore(flags);

}



void res_counter_uncharge(struct res_counter *counter, unsigned long val)

{

	res_counter_uncharge_until(counter, NULL, val);

}



static inline unsigned long long *

res_counter_member(struct res_counter *counter, int member)

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