linux-kernel - [tip:locking/urgent] locking/rtmutex: Set state back to running on error

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Message-ID: <tip-8671e69f00c2733c995d188b9f8d6f9cbb67897c@git.kernel.org>
Date:	Sat, 28 Feb 2015 02:00:48 -0800
From:	tip-bot for Sebastian Andrzej Siewior <tipbot@...or.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	bigeasy@...utronix.de, hpa@...or.com, tglx@...utronix.de,
	linux-kernel@...r.kernel.org, mingo@...nel.org,
	torvalds@...ux-foundation.org, peterz@...radead.org,
	maarten.lankhorst@...onical.com
Subject: [tip:locking/urgent] locking/rtmutex:
  Set state back to running on error

Commit-ID:  8671e69f00c2733c995d188b9f8d6f9cbb67897c
Gitweb:     http://git.kernel.org/tip/8671e69f00c2733c995d188b9f8d6f9cbb67897c
Author:     Sebastian Andrzej Siewior <bigeasy@...utronix.de>
AuthorDate: Fri, 27 Feb 2015 17:57:09 +0100
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Sat, 28 Feb 2015 10:47:37 +0100

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>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Maarten Lankhorst <maarten.lankhorst@...onical.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Link: http://lkml.kernel.org/r/1425056229-22326-4-git-send-email-bigeasy@linutronix.de
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 kernel/locking/rtmutex.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c
index e16e554..5845068 100644
--- a/kernel/locking/rtmutex.c
+++ b/kernel/locking/rtmutex.c
@@ -1193,6 +1193,7 @@ rt_mutex_slowlock(struct rt_mutex *lock, int state,
 		ret = __rt_mutex_slowlock(lock, state, timeout, &waiter);
 
 	if (unlikely(ret)) {
+		set_current_state(TASK_RUNNING);
 		if (rt_mutex_has_waiters(lock))
 			remove_waiter(lock, &waiter);
 		rt_mutex_handle_deadlock(ret, chwalk, &waiter);
--
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