delayacct: clear right task's flag after blkio completes

When I was implementing a latency analyzer tool by using task->delays
and other things, I found an issue in delayacct.  The issue is it should
clear the target's flag instead of current's in delayacct_blkio_end().

When I git blame delayacct, I found there're some similar issues we have
fixed in delayacct_blkio_end().

 - Commit c96f5471ce7d ("delayacct: Account blkio completion on the
   correct task") fixed the issue that it should account blkio
   completion on the target task instead of current.

 - Commit b512719f771a ("delayacct: fix crash in delayacct_blkio_end()
   after delayacct init failure") fixed the issue that it should check
   target task's delays instead of current task'.

It seems that delayacct_blkio_{begin, end} are error prone.

So I introduce a new paratmeter - the target task 'p' - to these
helpers.  After that change, the callsite will specifilly set the right
task, which should make it less error prone.

Link: https://lkml.kernel.org/r/20210414083720.24083-1-laoar.shao@gmail.com
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Josh Snyder <joshs@netflix.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 10 insertions, 10 deletions

diff --git a/include/linux/delayacct.h b/include/linux/delayacct.h
index 2d3bdcccf5eb..21651f946751 100644
--- a/include/linux/delayacct.h
+++ b/include/linux/delayacct.h
@@ -82,16 +82,16 @@ static inline int delayacct_is_task_waiting_on_io(struct task_struct *p)
 		return 0;
 }
 
-static inline void delayacct_set_flag(int flag)
+static inline void delayacct_set_flag(struct task_struct *p, int flag)
 {
-	if (current->delays)
-		current->delays->flags |= flag;
+	if (p->delays)
+		p->delays->flags |= flag;
 }
 
-static inline void delayacct_clear_flag(int flag)
+static inline void delayacct_clear_flag(struct task_struct *p, int flag)
 {
-	if (current->delays)
-		current->delays->flags &= ~flag;
+	if (p->delays)
+		p->delays->flags &= ~flag;
 }
 
 static inline void delayacct_tsk_init(struct task_struct *tsk)
@@ -114,7 +114,7 @@ static inline void delayacct_tsk_free(struct task_struct *tsk)
 
 static inline void delayacct_blkio_start(void)
 {
-	delayacct_set_flag(DELAYACCT_PF_BLKIO);
+	delayacct_set_flag(current, DELAYACCT_PF_BLKIO);
 	if (current->delays)
 		__delayacct_blkio_start();
 }
@@ -123,7 +123,7 @@ static inline void delayacct_blkio_end(struct task_struct *p)
 {
 	if (p->delays)
 		__delayacct_blkio_end(p);
-	delayacct_clear_flag(DELAYACCT_PF_BLKIO);
+	delayacct_clear_flag(p, DELAYACCT_PF_BLKIO);
 }
 
 static inline int delayacct_add_tsk(struct taskstats *d,
@@ -166,9 +166,9 @@ static inline void delayacct_thrashing_end(void)
 }
 
 #else
-static inline void delayacct_set_flag(int flag)
+static inline void delayacct_set_flag(struct task_struct *p, int flag)
 {}
-static inline void delayacct_clear_flag(int flag)
+static inline void delayacct_clear_flag(struct task_struct *p, int flag)
 {}
 static inline void delayacct_init(void)
 {}