linux-kernel - Re: [PATCH] Tasklets: Avoid duplicating __tasklet_{,hi

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Message-ID: <20080219162718.GA3372@ubuntu>
Date:	Tue, 19 Feb 2008 18:27:18 +0200
From:	"Ahmed S. Darwish" <darwish.07@...il.com>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Ingo Molnar <mingo@...hat.com>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] Tasklets: Avoid duplicating __tasklet_{,hi_}schedule()
	code

On Tue, Feb 19, 2008 at 04:52:52PM +0100, Ingo Molnar wrote:
> 
> * Ahmed S. Darwish <darwish.07@...il.com> wrote:
> 
> > -		local_irq_disable();
> > -		t->next = __get_cpu_var(tasklet_vec).list;
> > -		__get_cpu_var(tasklet_vec).list = t;
> > -		__raise_softirq_irqoff(TASKLET_SOFTIRQ);
> > -		local_irq_enable();
> > +		/* We were not lucky enough to run, reschedule. */
> > +		__tasklet_schedule(t);
> 
> i think there's a subtle difference that you missed: this one does 
> __raise_softirq_irqoff(), while __tasklet_schedule() does a 
> raise_softirq_irqoff(). (note the lack of undescores)
> 
> the reason is to avoid infinitely self-activating tasklets.
> 

Indeed, thanks a lot for the explanation. (maybe it's time to check
for new eyeglasses ;)).

Regards

-- 
Ahmed S. Darwish
Homepage: http://darwish.07.googlepages.com
Blog: http://darwish-07.blogspot.com

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