From: kuznet@ms2.inr.ac.ru
Message-Id: <200308270147.FAA07024@dub.inr.ac.ru>
Subject: Re: tasklet_kill will always hang for recursive tasklets on a UP
To: wa@almesberger.net (Werner Almesberger)
Date: Wed, 27 Aug 2003 05:47:18 +0400 (MSD)
Cc: quade@hsnr.de, nagendra_tomar@adaptec.com, linux-kernel@vger.kernel.org
In-Reply-To: <20030826145636.E1212@almesberger.net> from "Werner Almesberger" at  =?ISO-8859-1?Q?=20=E1?=
	=?ISO-8859-1?Q?=D7=C7?= 26, 2003 02:56:36 
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Hello!

> Hmm, actually, no. On UP, yes. But on SMP, you might tasklet_kill
> while the tasklet is running, but before it has had a chance to
> tasklet_schedule itself. tasklet_schedule will have no effect in
> this case.
> 
> Alexey, if my observation is correct, the property
> 
> | * If tasklet_schedule() is called, then tasklet is guaranteed
> |   to be executed on some cpu at least once after this.
> 
> does not hold if using tasklet_kill on SMP.

It still holds. tasklet_kill just waits for completion of scheduled
events. Well, it _assumes_ that cpu which calls tasklet_schedule
does not try to wake the tasklet after death. But it is from area
of pure scholastics already: waker and killer have to synchronize in some
way anyway. 

Alexey
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