Hi Andrew,
Sorry for the late answer.
On 23/07/2020 14:59, Andrew Cooper wrote:
On 23/07/2020 14:22, Julien Grall wrote:
Hi Jan,
On 23/07/2020 12:23, Jan Beulich wrote:
On 22.07.2020 18:53, Julien Grall wrote:
--- a/xen/arch/x86/irq.c
+++ b/xen/arch/x86/irq.c
@@ -1187,7 +1187,7 @@ struct irq_desc *pirq_spin_lock_irq_desc(
for ( ; ; )
{
- int irq = pirq->arch.irq;
+ int irq = read_atomic(&pirq->arch.irq);
There we go - I'd be fine this way, but I'm pretty sure Andrew
would want this to be ACCESS_ONCE(). So I guess now is the time
to settle which one to prefer in new code (or which criteria
there are to prefer one over the other).
I would prefer if we have a single way to force the compiler to do a
single access (read/write).
Unlikely to happen, I'd expect.
But I would really like to get rid of (or at least rename)
read_atomic()/write_atomic() specifically because they've got nothing to
do with atomic_t's and the set of functionality who's namespace they share.
Would you be happy if I rename both to READ_ONCE() and WRITE_ONCE()? I
would also suggest to move them implementation in a new header asm/lib.h.
Cheers,
--
Julien Grall
