On Tue, Oct 16, 2018 at 19:10:03 +0800, guangrong.xiao@xxxxxxxxx wrote: (snip) > diff --git a/include/qemu/ptr_ring.h b/include/qemu/ptr_ring.h > new file mode 100644 > index 0000000000..d8266d45f6 > --- /dev/null > +++ b/include/qemu/ptr_ring.h > @@ -0,0 +1,235 @@ (snip) > +#define SMP_CACHE_BYTES 64 > +#define ____cacheline_aligned_in_smp \ > + __attribute__((__aligned__(SMP_CACHE_BYTES))) You could use QEMU_ALIGNED() here. > + > +#define WRITE_ONCE(ptr, val) \ > + (*((volatile typeof(ptr) *)(&(ptr))) = (val)) > +#define READ_ONCE(ptr) (*((volatile typeof(ptr) *)(&(ptr)))) Why not atomic_read/set, like in the rest of the QEMU code base? Furthermore, READ_ONCE in the kernel implies smp_read_barrier_depends, whereas here you're not bringing that in. That means that your barrier pairing, e.g. > + /* Pairs with READ_ONCE in ptr_ring_consume. */ > + smp_wmb(); is incorrect for Alpha. Thanks, E.
