crypto: disable preemption while benchmarking RAID5 xor checksumming

With CONFIG_PREEMPT=y, we need to disable preemption while benchmarking
RAID5 xor checksumming to ensure we're actually measuring what we think
we're measuring.

Signed-off-by: Jim Kukunas <james.t.kukunas@linux.intel.com>
Signed-off-by: NeilBrown <neilb@suse.de>

1 files changed, 5 insertions, 0 deletions

diff --git a/crypto/xor.c b/crypto/xor.c
index 87884435bddb..84daa1111dad 100644
--- a/crypto/xor.c
+++ b/crypto/xor.c
@@ -21,6 +21,7 @@
 #include <linux/gfp.h>
 #include <linux/raid/xor.h>
 #include <linux/jiffies.h>
+#include <linux/preempt.h>
 #include <asm/xor.h>
 
 /* The xor routines to use.  */
@@ -69,6 +70,8 @@ do_xor_speed(struct xor_block_template *tmpl, void *b1, void *b2)
         tmpl->next = template_list;
         template_list = tmpl;
 
+        preempt_disable();
+
         /*
          * Count the number of XORs done during a whole jiffy, and use
          * this to calculate the speed of checksumming.  We use a 2-page
@@ -91,6 +94,8 @@ do_xor_speed(struct xor_block_template *tmpl, void *b1, void *b2)
                         max = count;
         }
 
+        preempt_enable();
+
         speed = max * (HZ * BENCH_SIZE / 1024);
         tmpl->speed = speed;