If you have an interrupt context write to the head and a different context
reading the head then I would make the variable volatile. Doing so ensures
that the reader actually loads the variable from memory when you intend for
it to do so and not have to worry about register optimizations getting in
the way.
Stuart
----- Original Message -----
From: "Tzahi Fadida" <Tzahi.ML2@xxxxxxxxx>
To: "Anupam Kapoor" <anupam.kapoor@xxxxxxxxx>
Cc: "Stuart Macdonald" <stuart@xxxxxxxxxxxxx>; "Stavros Passas"
<stabat@xxxxxxxxxxxx>; <kernelnewbies@xxxxxxxxxxxx>
Sent: Thursday, March 08, 2007 2:33 AM
Subject: Re: Thread safe circular buffer.
On Thursday 08 March 2007 10:30, Anupam Kapoor wrote:
On 3/8/07, Tzahi Fadida <Tzahi.ML2@xxxxxxxxx> wrote:
> On Wednesday 07 March 2007 20:45, Stuart Macdonald wrote:
> > If you are on IA32 architecture then memory reads and writes are
> > atomic
> > provided that they don't cross a cache line.
>
> And how do i make sure of that? declare the variable head volatile?
don't use volatile in the kernel. straight from horse's mouth :
I don't understand, LDD3 uses volatile in drivers. Now they say i can't.
What is the alternative?
http://thread.gmane.org/gmane.linux.kernel/423487/focus=424677
anupam
--
Regards,
Tzahi.
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Tzahi Fadida
Blog: http://tzahi.blogsite.org | Home Site: http://tzahi.webhop.info
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