Re: [patch] waitqueue optimization, 2.4.0-test7

From: yodaiken@fsmlabs.com
Date: Mon Aug 28 2000 - 12:45:26 EST


On Mon, Aug 28, 2000 at 07:51:55PM +0200, Ingo Molnar wrote:
> we have a number of other places that rely on clear_bit() being atomic -
> if this isnt true anymore on Alpha then we could make it nonatomic on x86

So what is the semantics of a non-atomic clear-bit?

BTW: here is the comment in include/asm-i386/bitops.h -- similar in
the other architectures I looked at.

* These have to be done with inline assembly: that way the bit-setting
 * is guaranteed to be atomic. All bit operations return 0 if the bit
 * was cleared before the operation and != 0 if it was not.

-- 
---------------------------------------------------------
Victor Yodaiken 
Finite State Machine Labs: The RTLinux Company.
 www.fsmlabs.com  www.rtlinux.com

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