[PATCH 6/7] cgroups: Add res counter common ancestor searching

Frederic Weisbecker
2011-07-11T14:15:32Z

Add a new API to find the common ancestor between two resource
counters. This includes the passed resource counter themselves.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Paul Menage <menage@google.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Aditya Kali <adityakali@google.com>
---
include/linux/res_counter.h | 2 ++
kernel/res_counter.c | 19 +++++++++++++++++++
2 files changed, 21 insertions(+), 0 deletions(-)

diff --git a/include/linux/res_counter.h b/include/linux/res_counter.h
index 8c421ac..354ed30 100644
--- a/include/linux/res_counter.h
+++ b/include/linux/res_counter.h
@@ -139,6 +139,8 @@ void res_counter_uncharge_until(struct res_counter *counter, struct res_counter
unsigned long val);
void res_counter_uncharge(struct res_counter *counter, unsigned long val);

+struct res_counter *res_counter_common_ancestor(struct res_counter *l, struct res_counter *r);
+
/**
* res_counter_margin - calculate chargeable space of a counter
* @cnt: the counter
diff --git a/kernel/res_counter.c b/kernel/res_counter.c
index 39f2513..1b2efd6 100644
--- a/kernel/res_counter.c
+++ b/kernel/res_counter.c
@@ -102,6 +102,25 @@ void res_counter_uncharge(struct res_counter *counter, unsigned long val)
res_counter_uncharge_until(counter, NULL, val);
}

+struct res_counter *
+res_counter_common_ancestor(struct res_counter *r1, struct res_counter *r2)
+{
+ struct res_counter *iter;
+
+ while (r1) {
+ iter = r2;
+ while (iter) {
+ if (iter == r1)
+ return iter;
+ iter = iter->parent;
+ }
+
+ r1 = r1->parent;
+ }
+
+ return NULL;
+}
+
static inline unsigned long long *
res_counter_member(struct res_counter *counter, int member)
{
--
1.7.5.4