linux-kernel - [PATCH 2/6] ftrace: use fls() to get the bits for dup

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Message-Id: <20200831031104.23322-3-richard.weiyang@linux.alibaba.com>
Date:   Mon, 31 Aug 2020 11:11:00 +0800
From:   Wei Yang <richard.weiyang@...ux.alibaba.com>
To:     rostedt@...dmis.org, mingo@...hat.com
Cc:     linux-kernel@...r.kernel.org,
        Wei Yang <richard.weiyang@...ux.alibaba.com>
Subject: [PATCH 2/6] ftrace: use fls() to get the bits for dup_hash()

The effect here is to get the number of bits, lets use fls() to do
this job.

Signed-off-by: Wei Yang <richard.weiyang@...ux.alibaba.com>
---
 kernel/trace/ftrace.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 12cb535769bc..9021e16fa079 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -1370,8 +1370,9 @@ static struct ftrace_hash *dup_hash(struct ftrace_hash *src, int size)
 	/*
 	 * Make the hash size about 1/2 the # found
 	 */
-	for (size /= 2; size; size >>= 1)
-		bits++;
+	bits = fls(size);
+	if (bits)
+		bits--;
 
 	/* Don't allocate too much */
 	if (bits > FTRACE_HASH_MAX_BITS)
-- 
2.20.1 (Apple Git-117)