[PATCH 5/8] res_counter: allow charge failure pointer to be null

[Frederic Weisbecker <fweisbec@gmail.com>]

So that callers of res_counter_charge() don't have to create and pass this
pointer even if they aren't interested in it.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Paul Menage <paul@paulmenage.org>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Aditya Kali <adityakali@google.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Cc: Tim Hockin <thockin@hockin.org>
Cc: Tejun Heo <htejun@gmail.com>
Acked-by: Kirill A. Shutemov <kirill@shutemov.name>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
 kernel/res_counter.c |    6 ++++--
 1 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/kernel/res_counter.c b/kernel/res_counter.c
index 86d72b8..644898a 100644
--- a/kernel/res_counter.c
+++ b/kernel/res_counter.c
@@ -43,14 +43,16 @@ int res_counter_charge_until(struct res_counter *counter,
 	unsigned long flags;
 	struct res_counter *c, *u;
 
-	*limit_fail_at = NULL;
+	if (limit_fail_at)
+		*limit_fail_at = NULL;
 	local_irq_save(flags);
 	for (c = counter; c != limit; c = c->parent) {
 		spin_lock(&c->lock);
 		ret = res_counter_charge_locked(c, val);
 		spin_unlock(&c->lock);
 		if (ret < 0) {
-			*limit_fail_at = c;
+			if (limit_fail_at)
+				*limit_fail_at = c;
 			goto undo;
 		}
 	}
-- 
1.7.5.4