Re: [PATCH RT] locking/rtmutex: do lockdep before actual locking in rt_spin_lock()

[Steven Rostedt]

On Wed, 11 Oct 2017 18:16:46 +0200
Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx> wrote:

> rt_spin_lock() should first do the lock annotation via lockdep and then
> do the actual locking. That way we learn about the deadlock from lockdep
> before it happens.
> 
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
> ---
>  kernel/locking/rtmutex.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c
> index 79f49d73e4d0..639cfdaae72f 100644
> --- a/kernel/locking/rtmutex.c
> +++ b/kernel/locking/rtmutex.c
> @@ -1153,8 +1153,8 @@ void __sched rt_spin_lock_slowunlock(struct rt_mutex *lock)
>  void __lockfunc rt_spin_lock(spinlock_t *lock)
>  {
>  	migrate_disable();
> -	rt_spin_lock_fastlock(&lock->lock, rt_spin_lock_slowlock);
>  	spin_acquire(&lock->dep_map, 0, 0, _RET_IP_);
> +	rt_spin_lock_fastlock(&lock->lock, rt_spin_lock_slowlock);
>  }
>  EXPORT_SYMBOL(rt_spin_lock);
>  

Acked-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>

-- Steve