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Subject[PATCH 2/2] hung_task: change check_hung_uninterruptible_tasks() to use for_each_process_thread_break/continue
Change check_hung_uninterruptible_tasks() to use the new helpers and remove
the "can_cont" logic from rcu_lock_break().

We could add for_each_process_thread_break/continue right into rcu_lock_break()
but see the next patch.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
---
kernel/hung_task.c | 25 +++++++++----------------
1 file changed, 9 insertions(+), 16 deletions(-)

diff --git a/kernel/hung_task.c b/kernel/hung_task.c
index b9132d1..13af558 100644
--- a/kernel/hung_task.c
+++ b/kernel/hung_task.c
@@ -148,20 +148,11 @@ static void check_hung_task(struct task_struct *t, unsigned long timeout)
* For preemptible RCU it is sufficient to call rcu_read_unlock in order
* to exit the grace period. For classic RCU, a reschedule is required.
*/
-static bool rcu_lock_break(struct task_struct *g, struct task_struct *t)
+static void rcu_lock_break(void)
{
- bool can_cont;
-
- get_task_struct(g);
- get_task_struct(t);
rcu_read_unlock();
cond_resched();
rcu_read_lock();
- can_cont = pid_alive(g) && pid_alive(t);
- put_task_struct(t);
- put_task_struct(g);
-
- return can_cont;
}

/*
@@ -185,16 +176,18 @@ static void check_hung_uninterruptible_tasks(unsigned long timeout)
hung_task_show_lock = false;
rcu_read_lock();
for_each_process_thread(g, t) {
- if (!max_count--)
+ /* use "==" to skip the TASK_KILLABLE tasks waiting on NFS */
+ if (t->state == TASK_UNINTERRUPTIBLE)
+ check_hung_task(t, timeout);
+
+ if (!--max_count)
goto unlock;
if (!--batch_count) {
batch_count = HUNG_TASK_BATCHING;
- if (!rcu_lock_break(g, t))
- goto unlock;
+ for_each_process_thread_break(g, t);
+ rcu_lock_break();
+ for_each_process_thread_continue(&g, &t);
}
- /* use "==" to skip the TASK_KILLABLE tasks waiting on NFS */
- if (t->state == TASK_UNINTERRUPTIBLE)
- check_hung_task(t, timeout);
}
unlock:
rcu_read_unlock();
--
2.5.0

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