Re: [RFC][PATCH] irq_work -v2

[Peter Zijlstra <peterz@infradead.org>]

On Fri, 2010-06-25 at 21:30 +0200, Andi Kleen wrote:
> > +             entry->next = next_flags(NULL, IRQ_WORK_BUSY);
> > +             entry->func(entry);
> 
> Needs compiler memory barrier here I think.
> 
> > +             /*
> > +              * Clear the BUSY bit and return to the free state if
> > +              * no-one else claimed it meanwhile.
> > +              */
> > +             cmpxchg(&entry->next, next_flags(NULL, IRQ_WORK_BUSY), NULL);
> > +     } 

Both the (indirect) function call and the cmpxchg imply a compiler
barrier.