| Message ID | 1451572003-2440-31-git-send-email-mst@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Fri, Jan 01, 2016 at 11:39:40AM +0200, Michael S. Tsirkin wrote: > virtio ring uses smp_wmb on SMP and wmb on !SMP, > the reason for the later being that it might be > talking to another kernel on the same SMP machine. > > This is exactly what __smp_XXX barriers do, > so switch to these instead of homegrown ifdef hacks. > > Cc: Peter Zijlstra <peterz@infradead.org> > Cc: Alexander Duyck <alexander.duyck@gmail.com> > Signed-off-by: Michael S. Tsirkin <mst@redhat.com> The subject and commit log should say virt_xxx and not __smp_xxx - I fixed this up in my tree. > --- > include/linux/virtio_ring.h | 25 ++++--------------------- > 1 file changed, 4 insertions(+), 21 deletions(-) > > diff --git a/include/linux/virtio_ring.h b/include/linux/virtio_ring.h > index 67e06fe..f3fa55b 100644 > --- a/include/linux/virtio_ring.h > +++ b/include/linux/virtio_ring.h > @@ -12,7 +12,7 @@ > * anyone care? > * > * For virtio_pci on SMP, we don't need to order with respect to MMIO > - * accesses through relaxed memory I/O windows, so smp_mb() et al are > + * accesses through relaxed memory I/O windows, so virt_mb() et al are > * sufficient. > * > * For using virtio to talk to real devices (eg. other heterogeneous > @@ -21,11 +21,10 @@ > * actually quite cheap. > */ > > -#ifdef CONFIG_SMP > static inline void virtio_mb(bool weak_barriers) > { > if (weak_barriers) > - smp_mb(); > + virt_mb(); > else > mb(); > } > @@ -33,7 +32,7 @@ static inline void virtio_mb(bool weak_barriers) > static inline void virtio_rmb(bool weak_barriers) > { > if (weak_barriers) > - smp_rmb(); > + virt_rmb(); > else > rmb(); > } > @@ -41,26 +40,10 @@ static inline void virtio_rmb(bool weak_barriers) > static inline void virtio_wmb(bool weak_barriers) > { > if (weak_barriers) > - smp_wmb(); > + virt_wmb(); > else > wmb(); > } > -#else > -static inline void virtio_mb(bool weak_barriers) > -{ > - mb(); > -} > - > -static inline void virtio_rmb(bool weak_barriers) > -{ > - rmb(); > -} > - > -static inline void virtio_wmb(bool weak_barriers) > -{ > - wmb(); > -} > -#endif > > struct virtio_device; > struct virtqueue; > -- > MST
diff --git a/include/linux/virtio_ring.h b/include/linux/virtio_ring.h index 67e06fe..f3fa55b 100644 --- a/include/linux/virtio_ring.h +++ b/include/linux/virtio_ring.h @@ -12,7 +12,7 @@ * anyone care? * * For virtio_pci on SMP, we don't need to order with respect to MMIO - * accesses through relaxed memory I/O windows, so smp_mb() et al are + * accesses through relaxed memory I/O windows, so virt_mb() et al are * sufficient. * * For using virtio to talk to real devices (eg. other heterogeneous @@ -21,11 +21,10 @@ * actually quite cheap. */ -#ifdef CONFIG_SMP static inline void virtio_mb(bool weak_barriers) { if (weak_barriers) - smp_mb(); + virt_mb(); else mb(); } @@ -33,7 +32,7 @@ static inline void virtio_mb(bool weak_barriers) static inline void virtio_rmb(bool weak_barriers) { if (weak_barriers) - smp_rmb(); + virt_rmb(); else rmb(); } @@ -41,26 +40,10 @@ static inline void virtio_rmb(bool weak_barriers) static inline void virtio_wmb(bool weak_barriers) { if (weak_barriers) - smp_wmb(); + virt_wmb(); else wmb(); } -#else -static inline void virtio_mb(bool weak_barriers) -{ - mb(); -} - -static inline void virtio_rmb(bool weak_barriers) -{ - rmb(); -} - -static inline void virtio_wmb(bool weak_barriers) -{ - wmb(); -} -#endif struct virtio_device; struct virtqueue;
virtio ring uses smp_wmb on SMP and wmb on !SMP, the reason for the later being that it might be talking to another kernel on the same SMP machine. This is exactly what __smp_XXX barriers do, so switch to these instead of homegrown ifdef hacks. Cc: Peter Zijlstra <peterz@infradead.org> Cc: Alexander Duyck <alexander.duyck@gmail.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com> --- include/linux/virtio_ring.h | 25 ++++--------------------- 1 file changed, 4 insertions(+), 21 deletions(-)