linux-kernel - [PATCH resend] cpumask: don't perform while loop in cpumask_next

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Date:	Mon,  2 Mar 2015 00:22:03 +0900
From:	Sergey Senozhatsky <sergey.senozhatsky@...il.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Tejun Heo <tj@...nel.org>, "David S. Miller" <davem@...emloft.net>,
	Amir Vadai <amirv@...lanox.com>, linux-kernel@...r.kernel.org,
	Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
	Sergey Senozhatsky <sergey.senozhatsky@...il.com>
Subject: [PATCH resend] cpumask: don't perform while loop in cpumask_next_and()

cpumask_next_and() is looking for cpumask_next() in src1 in a loop and
tests if found cpu is also present in src2. remove that loop, perform
cpumask_and() of src1 and src2 first and use that new mask to find
cpumask_next().

Apart from removing while loop, ./bloat-o-meter on x86_64 shows
add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-8 (-8)
function                                     old     new   delta
cpumask_next_and                              62      54      -8

Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@...il.com>
---
 lib/cpumask.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/lib/cpumask.c b/lib/cpumask.c
index b6513a9..5ab1553 100644
--- a/lib/cpumask.c
+++ b/lib/cpumask.c
@@ -37,10 +37,11 @@ EXPORT_SYMBOL(__next_cpu_nr);
 int cpumask_next_and(int n, const struct cpumask *src1p,
 		     const struct cpumask *src2p)
 {
-	while ((n = cpumask_next(n, src1p)) < nr_cpu_ids)
-		if (cpumask_test_cpu(n, src2p))
-			break;
-	return n;
+	struct cpumask tmp;
+
+	if (cpumask_and(&tmp, src1p, src2p))
+		return cpumask_next(n, &tmp);
+	return nr_cpu_ids;
 }
 EXPORT_SYMBOL(cpumask_next_and);
 
-- 
2.3.1.167.g7f4ba4b

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