Re: [rfc][patch 2/2] x86_64: FIFO ticket spinlocks

From: Nick Piggin
Date: Tue Jul 17 2007 - 11:08:26 EST


On Tue, Jul 17, 2007 at 04:25:42PM +0200, Andi Kleen wrote:
>
>
> When you revamp everything I guess it would make the locks
> easier to read to just put them into a .S file? They're
> out of line anyways.

It is a bit tricky because of the way kernel/spinlock.c uses
the the inline asm (that, and unlocks are inlined), and some
of the debugging code.

Also, I'm not exactly sure what is the best way to clean up
spinlocks, if it is even possible. I'm afraid to touch it
more than I have to :)

>
> In general they look ok.
>
> >
> > static inline void __raw_spin_unlock(raw_spinlock_t *lock)
> > {
> > - asm volatile("movl $1,%0" :"=m" (lock->slock) :: "memory");
> > + __asm__ __volatile__(
>
> Minor nit: please don't use these underlined keywords. They just look
> ugly and asm volatile works as well.

OK, I like that better too. I didn't even realise I changed this
because it is mechanical to do the __. That's good to know and I'll
change my habit now.
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