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List:       linux-kernel
Subject:    Re: [BUG] Variable stopmachine_state should be volatile
From:       Pavel Machek <pavel () ucw ! cz>
Date:       2005-11-30 22:19:31
Message-ID: 20051130221931.GB2056 () elf ! ucw ! cz
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Hi!

> The model to access variable stopmachine_state is that a main thread
> writes it and other threads read it. Its declaration has no sign
> volatile. In the while loop in function stopmachine, this variable is
> read, and compiler might optimize it by reading it once before the loop
> and not reading it again in the loop, so the thread might enter dead
> loop.

No. volatile may look like a solution, but it usually is not. You may
need some barriers, atomic_t or locking.
								Pavel
-- 
Thanks, Sharp!
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