Re: [PATCH 1/2] rt/threadirqs: don't need to save irqs in do_hardirq()

[Arnaldo Carvalho de Melo <acme@redhat.com>]

Em Thu, Feb 12, 2009 at 07:27:08PM +0100, Frederic Weisbecker escreveu:
> do_hardirq() has only one caller do_irqd() in a path where irq are already
> disabled. So we don't need to save irqs while holding desc->lock
> 
> Replace spin_lock_irqsave by spin_lock.
> 
> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
> ---
>  kernel/irq/manage.c |    4 ++--
>  1 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
> index ed7c5e3..6e9baf8 100644
> --- a/kernel/irq/manage.c
> +++ b/kernel/irq/manage.c
> @@ -905,7 +905,7 @@ static void do_hardirq(struct irq_desc *desc)
>  {
>  	unsigned long flags;

Can flags be removed too?
  
> -	spin_lock_irqsave(&desc->lock, flags);
> +	spin_lock(&desc->lock);
>  
>  	if (!(desc->status & IRQ_INPROGRESS))
>  		goto out;
> @@ -921,7 +921,7 @@ static void do_hardirq(struct irq_desc *desc)
>  	else
>  		thread_do_irq(desc);
>   out:
> -	spin_unlock_irqrestore(&desc->lock, flags);
> +	spin_unlock(&desc->lock);
>  
>  	if (waitqueue_active(&desc->wait_for_handler))
>  		wake_up(&desc->wait_for_handler);