From: Bart Van Assche <bvanassche@acm.org>
Date: Wed, 14 Aug 2013 15:33:35 +0000 (+0000)
Subject: libfc: Micro-optimize fc_setup_exch_mgr()
X-Git-Tag: next-20131105~12^2~1^2~13
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=a84ea8c7e839a73dab4bfc755f7f52e947690dab;p=karo-tx-linux.git

libfc: Micro-optimize fc_setup_exch_mgr()

Convert a loop into an ilog2() call. Although this code is not performance
sensitive this conversion makes this code easier to read.

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Cc: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: Robert Love <robert.w.love@intel.com>
---

diff --git a/drivers/scsi/libfc/fc_exch.c b/drivers/scsi/libfc/fc_exch.c
index cb2b900c011d..d0be52ab62c8 100644
--- a/drivers/scsi/libfc/fc_exch.c
+++ b/drivers/scsi/libfc/fc_exch.c
@@ -27,6 +27,7 @@
 #include <linux/slab.h>
 #include <linux/err.h>
 #include <linux/export.h>
+#include <linux/log2.h>
 
 #include <scsi/fc/fc_fc2.h>
 
@@ -2530,13 +2531,8 @@ int fc_setup_exch_mgr(void)
 	 * cpu on which exchange originated by simple bitwise
 	 * AND operation between fc_cpu_mask and exchange id.
 	 */
-	fc_cpu_mask = 1;
-	fc_cpu_order = 0;
-	while (fc_cpu_mask < nr_cpu_ids) {
-		fc_cpu_mask <<= 1;
-		fc_cpu_order++;
-	}
-	fc_cpu_mask--;
+	fc_cpu_order = ilog2(roundup_pow_of_two(nr_cpu_ids));
+	fc_cpu_mask = (1 << fc_cpu_order) - 1;
 
 	fc_exch_workqueue = create_singlethread_workqueue("fc_exch_workqueue");
 	if (!fc_exch_workqueue)