Re: [patch V3 4/7] rtmutex: Siplify remove_waiter()

[Steven Rostedt]

On Mon, 09 Jun 2014 20:28:08 -0000
Thomas Gleixner <t...@linutronix.de> wrote:

> Exit right away, when the removed waiter was not the top prioriy
> waiter on the lock. Get rid of the extra indent level.
> 
> Signed-off-by: Thomas Gleixner <t...@linutronix.de>
> ---
>  kernel/locking/rtmutex.c |   26 ++++++++++----------------
>  1 file changed, 10 insertions(+), 16 deletions(-)
> 
> Index: tip/kernel/locking/rtmutex.c
> ===================================================================
> --- tip.orig/kernel/locking/rtmutex.c
> +++ tip/kernel/locking/rtmutex.c
> @@ -780,7 +780,7 @@ static void remove_waiter(struct rt_mute
>  {
>       int first = (waiter == rt_mutex_top_waiter(lock));
>       struct task_struct *owner = rt_mutex_owner(lock);
> -     struct rt_mutex *next_lock = NULL;
> +     struct rt_mutex *next_lock;
>       unsigned long flags;
>  
>       raw_spin_lock_irqsave(&current->pi_lock, flags);
> @@ -788,28 +788,22 @@ static void remove_waiter(struct rt_mute
>       current->pi_blocked_on = NULL;
>       raw_spin_unlock_irqrestore(&current->pi_lock, flags);
>  

Add comment here, something like...

        /*
         * Only update priority if this task was the highest priority
         * task waiting on the lock, and there is an owner to update.
         */

Rest looks good.

Reviewed-by: Steven Rostedt <rost...@goodmis.org>

-- Steve


> -     if (!owner)
> +     if (!owner || !first)
>               return;
>  
> -     if (first) {
> +     raw_spin_lock_irqsave(&owner->pi_lock, flags);
>  
> -             raw_spin_lock_irqsave(&owner->pi_lock, flags);
> +     rt_mutex_dequeue_pi(owner, waiter);
>  
> -             rt_mutex_dequeue_pi(owner, waiter);
> +     if (rt_mutex_has_waiters(lock))
> +             rt_mutex_enqueue_pi(owner, rt_mutex_top_waiter(lock));
>  
> -             if (rt_mutex_has_waiters(lock)) {
> -                     struct rt_mutex_waiter *next;
> +     __rt_mutex_adjust_prio(owner);
>  
> -                     next = rt_mutex_top_waiter(lock);
> -                     rt_mutex_enqueue_pi(owner, next);
> -             }
> -             __rt_mutex_adjust_prio(owner);
> +     /* Store the lock on which owner is blocked or NULL */
> +     next_lock = task_blocked_on_lock(owner);
>  
> -             /* Store the lock on which owner is blocked or NULL */
> -             next_lock = task_blocked_on_lock(owner);
> -
> -             raw_spin_unlock_irqrestore(&owner->pi_lock, flags);
> -     }
> +     raw_spin_unlock_irqrestore(&owner->pi_lock, flags);
>  
>       if (!next_lock)
>               return;
> 

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