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 cb2b900c011d6b481fd8360e27e0543e2289ea40..d0be52ab62c877a14c9e172c18dee10f4e7707be 100644 (file)
--- 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)