Re: [PATCH] Fix the cpumask rewrite

[Linus Torvalds]

On Sat, 26 Jun 2004, Vojtech Pavlik wrote:
> 
> At least input pretty much relies on the fact that bitops don't need
> locking and act as memory barriers.

Well, plain test_bit() has always been more relaxed than the others, and
has never implied a memory barrier. Only the "test_and_set/clear()" things
imply memory barriers.

What we _could_ do (without changing any existing rules) is to add a
"__test_bit()" that is the relaxed version that doesn't do any of the
volatile etc. That would match the "__"  versions of the other bit
operations.

Then people who know that they use the bits without any volatility issues 
can use that one, and let the compiler optimize more. 

Hmm?

		Linus
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