(2012/05/14 19:08), Frederic Weisbecker wrote:

2012/5/14 KAMEZAWA Hiroyuki [off-list ref]:

quoted

(2012/05/12 6:19), Andrew Morton wrote:

quoted

On Fri, 11 May 2012 18:47:06 +0900
KAMEZAWA Hiroyuki [off-list ref] wrote:

quoted

From: Frederic Weisbecker <redacted>

At killing 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 wasting 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, ops is atomic and efficient.

Changelog since v2
 - removed unnecessary lines.
 - Fixed 'From' , this patch comes from his series. Please signed-off-by if good.

Signed-off-by: KAMEZAWA Hiroyuki <redacted>

Frederic's Signed-off-by: is unavaliable?

I didn't add his Signed-off because I modified his orignal patch a little...
I dropped res_counter_charge_until() because it's not used in this series,
I have no justification for adding it.
The idea of res_counter_uncharge_until() is from his patch.

The property of Signed-off-by is that as long as you
carry/relay/modify a patch, you add your
own signed-off-by. But you can't remove the signed off by of somebody
in the chain.

Even if you did a change in the patch, you need to preserve the chain.

Oh, sorry. 

There may be some special cases with "Original-patch-from:" tags used when
one heavily inspire from a patch without taking much of its original code.

Is this ok ?

==
[PATCH 2/6] memcg: add res_counter_uncharge_until()

From: Frederic Weisbecker <redacted>

At killing 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 wasting 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, ops is atomic and efficient.

Changelog since v2
 - removed unnecessary lines.
 - added 'From' , this patch comes from his one.

Signed-off-by: Frederic Weisbecker <redacted>
Signed-off-by: KAMEZAWA Hiroyuki <redacted>
---
 Documentation/cgroups/resource_counter.txt |    8 ++++++++
 include/linux/res_counter.h                |    3 +++
 kernel/res_counter.c                       |   10 ++++++++--
 3 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/Documentation/cgroups/resource_counter.txt b/Documentation/cgroups/resource_counter.txt
index 95b24d7..703103a 100644
--- a/Documentation/cgroups/resource_counter.txt
+++ b/Documentation/cgroups/resource_counter.txt

@@ -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

diff --git a/include/linux/res_counter.h b/include/linux/res_counter.h
index da81af0..d11c1cd 100644
--- a/include/linux/res_counter.h
+++ b/include/linux/res_counter.h

@@ -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

diff --git a/kernel/res_counter.c b/kernel/res_counter.c
index d508363..d9ea45e 100644
--- a/kernel/res_counter.c
+++ b/kernel/res_counter.c

@@ -99,13 +99,15 @@ 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);

@@ -113,6 +115,10 @@ 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)

-- 
1.7.4.1