Re: [RFC][PATCH] spinlock: Kill spin_unlock_wait()

[Oleg Nesterov]

On 01/05, Peter Zijlstra wrote:
>
> On Tue, 2011-01-04 at 17:45 +1100, Nick Piggin wrote:
> > So I agree, taking it out the back and shooting it in the head would make
> > the world a better place.
>
> There appear to be only two callsites of said horror,

Not sure I understand why spin_unlock_wait() is really awful, but OK.

> --- a/kernel/exit.c
> +++ b/kernel/exit.c
> @@ -956,7 +956,8 @@ NORET_TYPE void do_exit(long code)
>  	 * an exiting task cleaning up the robust pi futexes.
>  	 */
>  	smp_mb();
> -	raw_spin_unlock_wait(&tsk->pi_lock);
> +	raw_spin_lock_irq(&tsk->pi_lock);
> +	raw_spin_unlock_irq(&tsk->pi_lock);

then you can kill smp_mb() above.

Oleg.

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