diff options
| author | Sebastian Andrzej Siewior <bigeasy@linutronix.de> | 2013-11-15 14:46:50 (GMT) |
|---|---|---|
| committer | Scott Wood <scottwood@freescale.com> | 2014-05-14 18:38:29 (GMT) |
| commit | 9600ea2db9ec32d06bccc3c8f62123398fa17a82 (patch) | |
| tree | 49fbc7888c9e8e7f44fc4445edd92e3e8d40e815 /kernel/timer.c | |
| parent | 87c9c56df822bb559b9b9f66e98e0e0fab6ef73e (diff) | |
| download | linux-fsl-qoriq-9600ea2db9ec32d06bccc3c8f62123398fa17a82.tar.xz | |
rtmutex: use a trylock for waiter lock in trylock
Mike Galbraith captered the following:
| >#11 [ffff88017b243e90] _raw_spin_lock at ffffffff815d2596
| >#12 [ffff88017b243e90] rt_mutex_trylock at ffffffff815d15be
| >#13 [ffff88017b243eb0] get_next_timer_interrupt at ffffffff81063b42
| >#14 [ffff88017b243f00] tick_nohz_stop_sched_tick at ffffffff810bd1fd
| >#15 [ffff88017b243f70] tick_nohz_irq_exit at ffffffff810bd7d2
| >#16 [ffff88017b243f90] irq_exit at ffffffff8105b02d
| >#17 [ffff88017b243fb0] reschedule_interrupt at ffffffff815db3dd
| >--- <IRQ stack> ---
| >#18 [ffff88017a2a9bc8] reschedule_interrupt at ffffffff815db3dd
| > [exception RIP: task_blocks_on_rt_mutex+51]
| >#19 [ffff88017a2a9ce0] rt_spin_lock_slowlock at ffffffff815d183c
| >#20 [ffff88017a2a9da0] lock_timer_base.isra.35 at ffffffff81061cbf
| >#21 [ffff88017a2a9dd0] schedule_timeout at ffffffff815cf1ce
| >#22 [ffff88017a2a9e50] rcu_gp_kthread at ffffffff810f9bbb
| >#23 [ffff88017a2a9ed0] kthread at ffffffff810796d5
| >#24 [ffff88017a2a9f50] ret_from_fork at ffffffff815da04c
lock_timer_base() does a try_lock() which deadlocks on the waiter lock
not the lock itself.
This patch takes the waiter_lock with trylock so it should work from interrupt
context as well. If the fastpath doesn't work and the waiter_lock itself is
taken then it seems that the lock itself taken.
This patch also adds "rt_spin_unlock_after_trylock_in_irq" to keep lockdep
happy. If we managed to take the wait_lock in the first place we should also
be able to take it in the unlock path.
Cc: stable-rt@vger.kernel.org
Reported-by: Mike Galbraith <bitbucket@online.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Diffstat (limited to 'kernel/timer.c')
| -rw-r--r-- | kernel/timer.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/timer.c b/kernel/timer.c index 31757c0..b4f860c 100644 --- a/kernel/timer.c +++ b/kernel/timer.c @@ -1400,7 +1400,7 @@ unsigned long get_next_timer_interrupt(unsigned long now) expires = base->next_timer; } #ifdef CONFIG_PREEMPT_RT_FULL - rt_spin_unlock(&base->lock); + rt_spin_unlock_after_trylock_in_irq(&base->lock); #else spin_unlock(&base->lock); #endif |