RE: SMP share data declaration

[Hannibal B]

Spinlocks would be the one to protect the variable and synchronies
between CPU, But it's a busy waiting mechanism(just a word of caution).
Regards,
Hannibal

-----Original Message-----
From: Jesper Juhl [mailto:jesper.juhl@xxxxxxxxx] 
Sent: Friday, July 14, 2006 2:18 PM
To: wyb@xxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Subject: Re: SMP share data declaration

On 14/07/06, wyb@xxxxxxxxxxxxx <wyb@xxxxxxxxxxxxx> wrote:
> I know that an integer variable should be declared volatile to share
between
> CPUs.

NO. volatile won't protect you sufficiently.

Use spinlocks, mutexes, semaphores, barriers and the like to protect
variables from concurrent access. Using volatile for this is a BUG and
it won't work correctly.


-- 
Jesper Juhl <jesper.juhl@xxxxxxxxx>
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