From: Anton Blanchard <anton@samba.org>
Date: Wed, 20 Jun 2012 19:53:03 +0000 (-0700)
Subject: fault-inject: avoid call to random32() if fault injection is disabled
X-Git-Tag: v3.5-rc4~20^2~4
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=f39cdaebb89dc3e6dd4f3e75b6d4e87ef12190af;p=platform%2Fkernel%2Flinux-exynos.git

fault-inject: avoid call to random32() if fault injection is disabled

After enabling CONFIG_FAILSLAB I noticed random32 in profiles even if slub
fault injection wasn't enabled at runtime.

should_fail forces a comparison against random32() even if probability is
0:

        if (attr->probability <= random32() % 100)
                return false;

Add a check up front for probability == 0 and avoid all of the more
complicated checks.

Signed-off-by: Anton Blanchard <anton@samba.org>
Acked-by: Akinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

diff --git a/lib/fault-inject.c b/lib/fault-inject.c
index 6805453..f7210ad 100644
--- a/lib/fault-inject.c
+++ b/lib/fault-inject.c
@@ -101,6 +101,10 @@ static inline bool fail_stacktrace(struct fault_attr *attr)
 
 bool should_fail(struct fault_attr *attr, ssize_t size)
 {
+	/* No need to check any other properties if the probability is 0 */
+	if (attr->probability == 0)
+		return false;
+
 	if (attr->task_filter && !fail_task(attr, current))
 		return false;