From: Jim Kukunas <james.t.kukunas@linux.intel.com>
Date: Tue, 22 May 2012 03:54:03 +0000 (+1000)
Subject: crypto: wait for a full jiffy in do_xor_speed
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=6a328475cccacb99a13b06978091da936dd51d89;p=GitHub%2FLineageOS%2Fandroid_kernel_samsung_universal7580.git

crypto: wait for a full jiffy in do_xor_speed

In the existing do_xor_speed(), there is no guarantee that we actually
run do_2() for a full jiffy. We get the current jiffy, then run do_2()
until the next jiffy.

Instead, let's get the current jiffy, then wait until the next jiffy
to start our test.

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

diff --git a/crypto/xor.c b/crypto/xor.c
index b75182d8ab1..87884435bdd 100644
--- a/crypto/xor.c
+++ b/crypto/xor.c
@@ -63,7 +63,7 @@ static void
 do_xor_speed(struct xor_block_template *tmpl, void *b1, void *b2)
 {
 	int speed;
-	unsigned long now;
+	unsigned long now, j;
 	int i, count, max;
 
 	tmpl->next = template_list;
@@ -76,9 +76,11 @@ do_xor_speed(struct xor_block_template *tmpl, void *b1, void *b2)
 	 */
 	max = 0;
 	for (i = 0; i < 5; i++) {
-		now = jiffies;
+		j = jiffies;
 		count = 0;
-		while (jiffies == now) {
+		while ((now = jiffies) == j)
+			cpu_relax();
+		while (time_before(jiffies, now + 1)) {
 			mb(); /* prevent loop optimzation */
 			tmpl->do_2(BENCH_SIZE, b1, b2);
 			mb();