linux-kernel - [PATCH 3/3] locking: rtmutex: set state back to running on error

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Date:	Fri, 27 Feb 2015 17:57:09 +0100
From:	Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To:	linux-kernel@...r.kernel.org
Cc:	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...hat.com>,
	Maarten Lankhorst <maarten.lankhorst@...onical.com>,
	Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Subject: [PATCH 3/3] locking: rtmutex: set state back to running on error

The "usual" path is:
- rt_mutex_slowlock()
 - set_current_state()
 - task_blocks_on_rt_mutex() (ret 0)
 - __rt_mutex_slowlock()
   - sleep or not but do return with __set_current_state(TASK_RUNNING)
 - back to caller.

In the early error case where task_blocks_on_rt_mutex() return -EDEADLK
we never change the task's state back to RUNNING. I assume this is
intended. Without this change after ww_mutex using rt_mutex the selftest
passes but later I get plenty of
| bad: scheduling from the idle thread!
backtraces.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
---
 kernel/locking/rtmutex.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c
index 6d7d72ffa619..c4d07f254bb4 100644
--- a/kernel/locking/rtmutex.c
+++ b/kernel/locking/rtmutex.c
@@ -1305,6 +1305,7 @@ rt_mutex_slowlock(struct rt_mutex *lock, int state,
 	}
 
 	if (unlikely(ret)) {
+		set_current_state(TASK_RUNNING);
 		if (rt_mutex_has_waiters(lock))
 			remove_waiter(lock, &waiter);
 		/* ww_mutex need the error reported */
-- 
2.1.4

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