Re: Another ldcw inline assembler patch

[Grant Grundler <grundler@parisc-linux.org>]

On Sat, Jun 28, 2008 at 05:34:07PM -0600, Matthew Wilcox wrote:
> On Sat, Jun 28, 2008 at 06:07:57PM -0400, John David Anglin wrote:
> > There are two reasons to expose the memory *a in the asm:
> > 
> > 1) To prevent the compiler from discarding a preceeding write to *a, and
> > 2) to prevent it from caching *a in a register over the asm.
> 
> Do either of those scenarios apply, given that every usage of this is
> preceded by an asm clobbering memory?
> 
> I believe the correct thing to do is to take out the two mb()s in the
> various spin_lock routines and make the __ldcw() macro itself clobber
> memory.

I agree. Do you want jda to submit another patch or did you want kyle to
take jda's patch and apply a second one to remove the mb()'s?

thanks.
grant

> 
> -- 
> Intel are signing my paycheques ... these opinions are still mine
> "Bill, look, we understand that you're interested in selling us this
> operating system, but compare it to ours.  We can't possibly take such
> a retrograde step."
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