On Thu, 05 Jun 2014 15:28:33 -0000
Thomas Gleixner <[email protected]> wrote:
> @@ -536,8 +569,9 @@ static int task_blocks_on_rt_mutex(struc
> {
> struct task_struct *owner = rt_mutex_owner(lock);
> struct rt_mutex_waiter *top_waiter = waiter;
> + struct rt_mutex *next_lock = NULL;
> unsigned long flags;
> - int chain_walk = 0, res;
> + int chain_walk, res;
>
> /*
> * Early deadlock detection. We really don't want the task to
> @@ -569,19 +603,21 @@ static int task_blocks_on_rt_mutex(struc
> if (!owner)
> return 0;
>
> + raw_spin_lock_irqsave(&owner->pi_lock, flags);
> if (waiter == rt_mutex_top_waiter(lock)) {
> - raw_spin_lock_irqsave(&owner->pi_lock, flags);
> rt_mutex_dequeue_pi(owner, top_waiter);
> rt_mutex_enqueue_pi(owner, waiter);
>
> __rt_mutex_adjust_prio(owner);
> if (owner->pi_blocked_on)
> chain_walk = 1;
> - raw_spin_unlock_irqrestore(&owner->pi_lock, flags);
> - }
> - else if (debug_rt_mutex_detect_deadlock(waiter, detect_deadlock))
> + } else if (debug_rt_mutex_detect_deadlock(waiter, detect_deadlock)) {
> chain_walk = 1;
> + }
> + if (owner->pi_blocked_on)
> + next_lock = owner->pi_blocked_on->lock;
>
> + raw_spin_unlock_irqrestore(&owner->pi_lock, flags);
> if (!chain_walk)
> return 0;
Here's another optimization:
/* If the owner is not blocked, no need to walk the chain */
if (!chain_walk || !next_lock)
return 0;
-- Steve
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