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

[Peng Tao]

From: Andrew Perepechko <andrew_perepechko@xxxxxxxxxxx>

This patch implements log2 using fls.

Reviewed-by: alexander_zarochentsev@xxxxxxxxxxx
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-3496
Signed-off-by: Andrew Perepechko <andrew_perepechko@xxxxxxxxxxx>
Reviewed-by: Alexander Boyko <Alexander_Boyko@xxxxxxxxxxx>
Reviewed-by: Vitaly Fertman <Vitaly_Fertman@xxxxxxxxxxx>
Lustre-change: http://review.whamcloud.com/6757
Reviewed-by: John L. Hammond <john.hammond@xxxxxxxxx>
Reviewed-by: Bob Glossman <bob.glossman@xxxxxxxxx>
Reviewed-by: Oleg Drokin <oleg.drokin@xxxxxxxxx>
Signed-off-by: Peng Tao <bergwolf@xxxxxxxxx>
Signed-off-by: Andreas Dilger <andreas.dilger@xxxxxxxxx>
---
 .../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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