Re: [PATCH] Fix the cpumask rewrite

[Linus Torvalds]

On Sat, 26 Jun 2004, Linus Torvalds wrote:
> 
> Why not? The thing is, the bitmap operators are supposed to work on 
> volatile data, ie people are literally using them for things like
> 
> 	while (test_bit(TASKLET_STATE_SCHED, &t->state));

Ahh. That one is part of a "do while ()" loop, and grep mis-identifies it. 
So parisc gets it right, because the whole loop is

	do
		yield();
	while (test_bit(TASKLET_STATE_SCHED, &t->state));

so at least the compiler didn't get to optimize it away.

Hopefully we don't have any other busy loops either - even if it is a busy
loop, we should have a "cpu_relax()" or something there just to keep power
levels down, and that should also tell the compiler not to do anything
silly. But the conceptual point stands.

		Linus
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