From 50bdd430c20566b13d8bc59946184b08f5875de6 Mon Sep 17 00:00:00 2001 From: Glauber Costa Date: Tue, 18 Dec 2012 14:22:04 -0800 Subject: res_counter: return amount of charges after res_counter_uncharge() 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 Reviewed-by: Michal Hocko Acked-by: Kamezawa Hiroyuki Acked-by: David Rientjes Cc: Johannes Weiner Cc: Suleiman Souhlal Cc: Tejun Heo Cc: Christoph Lameter Cc: Frederic Weisbecker Cc: Greg Thelen Cc: JoonSoo Kim Cc: Mel Gorman Cc: Pekka Enberg Cc: Rik van Riel Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/res_counter.h | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) (limited to 'include/linux/res_counter.h') diff --git a/include/linux/res_counter.h b/include/linux/res_counter.h index 6f54e40fa21..5ae8456d967 100644 --- a/include/linux/res_counter.h +++ b/include/linux/res_counter.h @@ -125,14 +125,16 @@ int res_counter_charge_nofail(struct res_counter *counter, * * these calls check for usage underflow and show a warning on the console * _locked call expects the counter->lock to be taken + * + * returns the total charges still present in @counter. */ -void res_counter_uncharge_locked(struct res_counter *counter, unsigned long val); -void res_counter_uncharge(struct res_counter *counter, unsigned long val); +u64 res_counter_uncharge_locked(struct res_counter *counter, unsigned long val); +u64 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); +u64 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 -- cgit v1.2.3-70-g09d2