Re: [PATCH] removal of unnecessary irq save/restore in tasklet_hi_schedule

From: Stuart MacDonald (stuartm@connecttech.com)
Date: Wed Jul 26 2000 - 09:43:17 EST


From: "Linus Torvalds" <torvalds@transmeta.com>
> On Wed, 26 Jul 2000, Daniel Marmier wrote:
> > If my understanding is correct :
> > a) tasklet_hi_schedule is to be called by hardirqs
> > b) hardirqs cannot be re-entered
>
> No, hard-irq's _can_ be re-entered. One hard-irq cannot re-enter itself,
> but you can have _different_ irq's enter each other. As such, to avoid
> deadlock in on the local CPU the current code is needed..

So the following is allowable?

hard_irq_a() {
..
  hard_irq_b();
..
}

hard_irq_b() {
..
  hard_irq_a();
..
}

Then hard_irq_a has re-entered itself.

..Stu

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