[PATCH 06/19] libfc: Micro-optimize fc_setup_exch_mgr()

Robert Love
2013-10-21T18:00:58Z

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>
---
drivers/scsi/libfc/fc_exch.c | 10 +++-------
1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/drivers/scsi/libfc/fc_exch.c b/drivers/scsi/libfc/fc_exch.c
index cb2b900..d0be52a 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)