linux-kernel - [RFC][PATCH 4/5] percpu: Fix abs() usage in percpu_counter

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Date:	Mon, 14 Sep 2015 18:05:23 -0700
From:	John Stultz <john.stultz@...aro.org>
To:	LKML <linux-kernel@...r.kernel.org>
Cc:	John Stultz <john.stultz@...aro.org>,
	Dave Chinner <dchinner@...hat.com>, Tejun Heo <tj@...nel.org>,
	Ingo Molnar <mingo@...nel.org>
Subject: [RFC][PATCH 4/5] percpu: Fix abs() usage in percpu_counter_compare()

s64 values should not be used with abs(), as is one
in __percpu_counter_compare(), since it may cap the
result to 32-bits.

This patch modifies __percpu_counter_compare() to
use abs64() instead.

Cc: Dave Chinner <dchinner@...hat.com>
Cc: Tejun Heo <tj@...nel.org>
Cc: Ingo Molnar <mingo@...nel.org>
Signed-off-by: John Stultz <john.stultz@...aro.org>
---
 lib/percpu_counter.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/percpu_counter.c b/lib/percpu_counter.c
index f051d69..3d1aba9 100644
--- a/lib/percpu_counter.c
+++ b/lib/percpu_counter.c
@@ -203,7 +203,7 @@ int __percpu_counter_compare(struct percpu_counter *fbc, s64 rhs, s32 batch)
 
 	count = percpu_counter_read(fbc);
 	/* Check to see if rough count will be sufficient for comparison */
-	if (abs(count - rhs) > (batch * num_online_cpus())) {
+	if (abs64(count - rhs) > (batch * num_online_cpus())) {
 		if (count > rhs)
 			return 1;
 		else
-- 
1.9.1

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