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Subject[PATCH 04/10] cgroups: add res counter common ancestor searching
Date
From: "Kirill A. Shutemov" <kirill@shutemov.name>

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

Signed-off-by: Kirill A. Shutemov <kirill@shutemov.name>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Paul Menage <paul@paulmenage.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Aditya Kali <adityakali@google.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Tim Hockin <thockin@hockin.org>
Cc: Tejun Heo <htejun@gmail.com>
Cc: Containers <containers@lists.linux-foundation.org>
Cc: Glauber Costa <glommer@gmail.com>
Cc: Cgroups <cgroups@vger.kernel.org>
Cc: Daniel J Walsh <dwalsh@redhat.com>
Cc: "Daniel P. Berrange" <berrange@redhat.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Max Kellermann <mk@cm4all.com>
Cc: Mandeep Singh Baines <msb@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
include/linux/res_counter.h | 3 +++
kernel/res_counter.c | 33 +++++++++++++++++++++++++++++++++
2 files changed, 36 insertions(+), 0 deletions(-)
diff --git a/include/linux/res_counter.h b/include/linux/res_counter.h
index de4ba29..558f39b 100644
--- a/include/linux/res_counter.h
+++ b/include/linux/res_counter.h
@@ -147,6 +147,9 @@ static inline void res_counter_uncharge(struct res_counter *counter,
res_counter_uncharge_until(counter, NULL, 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 40f15aa..6dc6164 100644
--- a/kernel/res_counter.c
+++ b/kernel/res_counter.c
@@ -91,6 +91,39 @@ void res_counter_uncharge_until(struct res_counter *counter,
local_irq_restore(flags);
}

+/*
+ * Walk through r1 and r2 parents and try to find the closest common one
+ * between both. If none is found, it returns NULL.
+ */
+struct res_counter *
+res_counter_common_ancestor(struct res_counter *r1, struct res_counter *r2)
+{
+ struct res_counter *iter;
+ int r1_depth = 0, r2_depth = 0;
+
+ for (iter = r1; iter; iter = iter->parent)
+ r1_depth++;
+
+ for (iter = r2; iter; iter = iter->parent)
+ r2_depth++;
+
+ while (r1_depth > r2_depth) {
+ r1 = r1->parent;
+ r1_depth--;
+ }
+
+ while (r2_depth > r1_depth) {
+ r2 = r2->parent;
+ r2_depth--;
+ }
+
+ while (r1 != r2) {
+ r1 = r1->parent;
+ r2 = r2->parent;
+ }
+
+ return r1;
+}

static inline unsigned long long *
res_counter_member(struct res_counter *counter, int member)
--
1.7.5.4


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