[PATCH 2/3] clockesource: set override clocksource

[Alex Shi <alex.shi@intel.com>]

Shrink the mutex region. And save a clocksource_select action if set
clocksource is same as current clocksource.

Signed-off-by: Alex Shi <alex.shi@intel.com>
---
 kernel/time/clocksource.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c
index 021c159..9d6c333 100644
--- a/kernel/time/clocksource.c
+++ b/kernel/time/clocksource.c
@@ -885,13 +885,15 @@ static ssize_t sysfs_override_clocksource(struct device *dev,
 {
 	size_t ret;
 
-	mutex_lock(&clocksource_mutex);
-
 	ret = sysfs_get_uname(buf, override_name, count);
-	if (ret >= 0)
-		clocksource_select();
+	if (ret >= 0) {
+		if (!strcmp(curr_clocksource->name, override_name))
+			return ret;
 
-	mutex_unlock(&clocksource_mutex);
+		mutex_lock(&clocksource_mutex);
+		clocksource_select();
+		mutex_unlock(&clocksource_mutex);
+	}
 
 	return ret;
 }
-- 
1.7.12