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virtio_ring: update weak barriers to use virt_xxx 

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 virt_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>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
This commit is contained in:
Michael S. Tsirkin 2015-12-27 17:55:35 +02:00
parent d307fb16f7
commit a65961272e
1 changed files with 4 additions and 21 deletions
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25
include/linux/virtio_ring.h
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@ -12,7 +12,7 @@
* anyone care? * anyone care?
* *
* For virtio_pci on SMP, we don't need to order with respect to MMIO * 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. * sufficient.
* *
* For using virtio to talk to real devices (eg. other heterogeneous * For using virtio to talk to real devices (eg. other heterogeneous
@ -21,11 +21,10 @@
* actually quite cheap. * actually quite cheap.
*/ */
#ifdef CONFIG_SMP
static inline void virtio_mb(bool weak_barriers) static inline void virtio_mb(bool weak_barriers)
{ {
if (weak_barriers) if (weak_barriers)
smp_mb(); virt_mb();
else else
mb(); mb();
} }
@ -33,7 +32,7 @@ static inline void virtio_mb(bool weak_barriers)
static inline void virtio_rmb(bool weak_barriers) static inline void virtio_rmb(bool weak_barriers)
{ {
if (weak_barriers) if (weak_barriers)
smp_rmb(); virt_rmb();
else else
rmb(); rmb();
} }
@ -41,26 +40,10 @@ static inline void virtio_rmb(bool weak_barriers)
static inline void virtio_wmb(bool weak_barriers) static inline void virtio_wmb(bool weak_barriers)
{ {
if (weak_barriers) if (weak_barriers)
smp_wmb(); virt_wmb();
else else
wmb(); 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 virtio_device;
struct virtqueue; struct virtqueue;