[PATCH] delayacct: fix incomplete disable operation when switch enable to disable

[cgel . zte]

From: Yang Yang <yang.yang29@xxxxxxxxxx> 

When a task is created after delayacct is enabled, kernel will do all the
delay accountings for that task. The problems is if user disables delayacct
by set /proc/sys/kernel/task_delayacct to zero, only blkio delay accounting
is disabled.

Now disable all the kinds of delay accountings when
/proc/sys/kernel/task_delayacct sets to zero.

Signed-off-by: Yang Yang <yang.yang29@xxxxxxxxxx>
Reported-by: Zeal Robot <zealci@xxxxxxxxxx>
---
 include/linux/delayacct.h | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/include/linux/delayacct.h b/include/linux/delayacct.h
index b96d68f310a2..c675cfb6437e 100644
--- a/include/linux/delayacct.h
+++ b/include/linux/delayacct.h
@@ -131,36 +131,54 @@ static inline __u64 delayacct_blkio_ticks(struct task_struct *tsk)
 
 static inline void delayacct_freepages_start(void)
 {
+	if (!static_branch_unlikely(&delayacct_key))
+		return;
+
 	if (current->delays)
 		__delayacct_freepages_start();
 }
 
 static inline void delayacct_freepages_end(void)
 {
+	if (!static_branch_unlikely(&delayacct_key))
+		return;
+
 	if (current->delays)
 		__delayacct_freepages_end();
 }
 
 static inline void delayacct_thrashing_start(void)
 {
+	if (!static_branch_unlikely(&delayacct_key))
+		return;
+
 	if (current->delays)
 		__delayacct_thrashing_start();
 }
 
 static inline void delayacct_thrashing_end(void)
 {
+	if (!static_branch_unlikely(&delayacct_key))
+		return;
+
 	if (current->delays)
 		__delayacct_thrashing_end();
 }
 
 static inline void delayacct_swapin_start(void)
 {
+	if (!static_branch_unlikely(&delayacct_key))
+		return;
+
 	if (current->delays)
 		__delayacct_swapin_start();
 }
 
 static inline void delayacct_swapin_end(void)
 {
+	if (!static_branch_unlikely(&delayacct_key))
+		return;
+
 	if (current->delays)
 		__delayacct_swapin_end();
 }
-- 
2.25.1