Re: [PATCH] Documentation/preempt-locking.txt clarification

From: Andrew Morton
Date: Wed Nov 10 2004 - 03:59:02 EST

Thomas Hood <jdthood@xxxxxxxxxxx> wrote:
> I have tried to clarify the text while at the same time
> preserving the original meaning. Everything is pretty clear
> now except for the last paragraph which I still find baffling.
> I don't know what "a test to see if preemption is required" is
> exactly and I don't understand when such a test is required.

I guess it's saying that if you do this:


then you should follow that by


just in case someone told this task to preempt itself while it had
interrupts disabled.

But I don't see why that's needed: if the preempt command came from another
CPU then this CPU will take the cross-CPU interrupt as soon as interrupts
are enabled. And the preempt command couldn't have come from _this_ CPU,
because it had interrupts disabled.

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