linux-kernel - [PATCH 24/26] staging/lustre/lprocfs: implement log2 using bitops

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Date:	Fri, 15 Nov 2013 00:43:11 +0800
From:	Peng Tao <bergwolf@...il.com>
To:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:	linux-kernel@...r.kernel.org,
	Andrew Perepechko <andrew_perepechko@...atex.com>,
	Peng Tao <bergwolf@...il.com>,
	Andreas Dilger <andreas.dilger@...el.com>
Subject: [PATCH 24/26] staging/lustre/lprocfs: implement log2 using bitops

From: Andrew Perepechko <andrew_perepechko@...atex.com>

This patch implements log2 using fls.

Reviewed-by: alexander_zarochentsev@...atex.com
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-3496
Signed-off-by: Andrew Perepechko <andrew_perepechko@...atex.com>
Reviewed-by: Alexander Boyko <Alexander_Boyko@...atex.com>
Reviewed-by: Vitaly Fertman <Vitaly_Fertman@...atex.com>
Lustre-change: http://review.whamcloud.com/6757
Reviewed-by: John L. Hammond <john.hammond@...el.com>
Reviewed-by: Bob Glossman <bob.glossman@...el.com>
Reviewed-by: Oleg Drokin <oleg.drokin@...el.com>
Signed-off-by: Peng Tao <bergwolf@...il.com>
Signed-off-by: Andreas Dilger <andreas.dilger@...el.com>
---
 .../lustre/lustre/obdclass/lprocfs_status.c        |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/staging/lustre/lustre/obdclass/lprocfs_status.c b/drivers/staging/lustre/lustre/obdclass/lprocfs_status.c
index 428a023..b2647c8 100644
--- a/drivers/staging/lustre/lustre/obdclass/lprocfs_status.c
+++ b/drivers/staging/lustre/lustre/obdclass/lprocfs_status.c
@@ -1961,10 +1961,10 @@ EXPORT_SYMBOL(lprocfs_oh_tally);
 
 void lprocfs_oh_tally_log2(struct obd_histogram *oh, unsigned int value)
 {
-	unsigned int val;
+	unsigned int val = 0;
 
-	for (val = 0; ((1 << val) < value) && (val <= OBD_HIST_MAX); val++)
-		;
+	if (likely(value != 0))
+		val = min(fls(value - 1), OBD_HIST_MAX);
 
 	lprocfs_oh_tally(oh, val);
 }
-- 
1.7.9.5

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