On Tue, 20 May 2008, Gregory Haskins wrote:
> From: Peter W. Morreale <pmorreale@xxxxxxxxxx>
>
> Remove the redundant attempt to get the lock. While it is true that the
> exit path with this patch adds an un-necessary xchg (in the event the
> lock is granted without further traversal in the loop) experimentation
> shows that we almost never encounter this situation.
>
> Signed-off-by: Peter W. Morreale <pmorreale@xxxxxxxxxx>
> Signed-off-by: Gregory Haskins <ghaskins@xxxxxxxxxx>
> ---
>
> kernel/rtmutex.c | 6 ------
> 1 files changed, 0 insertions(+), 6 deletions(-)
>
> diff --git a/kernel/rtmutex.c b/kernel/rtmutex.c
> index ec1f7d4..1da7813 100644
> --- a/kernel/rtmutex.c
> +++ b/kernel/rtmutex.c
> @@ -785,12 +785,6 @@ rt_spin_lock_slowlock(struct rt_mutex *lock)
> spin_lock_irqsave(&lock->wait_lock, flags);
> init_lists(lock);
>
> - /* Try to acquire the lock again: */
> - if (do_try_to_take_rt_mutex(lock, STEAL_LATERAL)) {
> - spin_unlock_irqrestore(&lock->wait_lock, flags);
> - return;
> - }
> -
This would suggested that lock stealing doesn't happen. On lock stealing,
this is the condition that is triggered and we have a nice quick exit.
-- Steve
> BUG_ON(rt_mutex_owner(lock) == current);
>
> /*
>
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