[PATCH RFC 10/13] exit: Add struct wait_opts's member held_lock and use it for tasklist_lock

[Kirill Tkhai <ktkhai@odin.com>]

These will be used in next patches.

Signed-off-by: Kirill Tkhai <ktkhai@odin.com>
---
 kernel/exit.c |   10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/kernel/exit.c b/kernel/exit.c
index c84f3e4..bb9d165 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -953,6 +953,7 @@ struct wait_opts {
 
 	wait_queue_t		child_wait;
 	int			notask_error;
+	rwlock_t		*held_lock;
 };
 
 static inline
@@ -1034,7 +1035,7 @@ static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p)
 		int why;
 
 		get_task_struct(p);
-		read_unlock(&tasklist_lock);
+		read_unlock(wo->held_lock);
 		sched_annotate_sleep();
 
 		if ((exit_code & 0x7f) == 0) {
@@ -1056,7 +1057,7 @@ static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p)
 	/*
 	 * We own this thread, nobody else can reap it.
 	 */
-	read_unlock(&tasklist_lock);
+	read_unlock(wo->held_lock);
 	sched_annotate_sleep();
 
 	/*
@@ -1246,7 +1247,7 @@ static int wait_task_stopped(struct wait_opts *wo,
 	get_task_struct(p);
 	pid = task_pid_vnr(p);
 	why = ptrace ? CLD_TRAPPED : CLD_STOPPED;
-	read_unlock(&tasklist_lock);
+	read_unlock(wo->held_lock);
 	sched_annotate_sleep();
 
 	if (unlikely(wo->wo_flags & WNOWAIT))
@@ -1309,7 +1310,7 @@ static int wait_task_continued(struct wait_opts *wo, struct task_struct *p)
 
 	pid = task_pid_vnr(p);
 	get_task_struct(p);
-	read_unlock(&tasklist_lock);
+	read_unlock(wo->held_lock);
 	sched_annotate_sleep();
 
 	if (!wo->wo_info) {
@@ -1538,6 +1539,7 @@ static long do_wait(struct wait_opts *wo)
 
 	set_current_state(TASK_INTERRUPTIBLE);
 	read_lock(&tasklist_lock);
+	wo->held_lock = &tasklist_lock;
 	for_each_thread(current, tsk) {
 		retval = do_wait_thread(wo, tsk);
 		if (retval)