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authorGlauber Costa <glommer@parallels.com>2012-12-18 14:22:04 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2012-12-18 15:02:12 -0800
commit50bdd430c20566b13d8bc59946184b08f5875de6 (patch)
tree15ccc558002367c3d2c6b092ccc1d49e6d14acf1 /include
parent6a1a0d3b625a4091e7a0eb249aefc6a644385149 (diff)
downloadvexpress-lsk-50bdd430c20566b13d8bc59946184b08f5875de6.tar.gz
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 <glommer@parallels.com> Reviewed-by: Michal Hocko <mhocko@suse.cz> Acked-by: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Suleiman Souhlal <suleiman@google.com> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Frederic Weisbecker <fweisbec@redhat.com> Cc: Greg Thelen <gthelen@google.com> Cc: JoonSoo Kim <js1304@gmail.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Pekka Enberg <penberg@cs.helsinki.fi> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include')
-rw-r--r--include/linux/res_counter.h12
1 files changed, 7 insertions, 5 deletions
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