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Commit 9e1a27ea authored by Alexander Duyck's avatar Alexander Duyck Committed by Rusty Russell
Browse files

virtio_ring: Update weak barriers to use dma_wmb/rmb 



This change makes it so that instead of using smp_wmb/rmb which varies
depending on the kernel configuration we can can use dma_wmb/rmb which for
most architectures should be equal to or slightly more strict than
smp_wmb/rmb.

The advantage to this is that these barriers are available to uniprocessor
builds as well so the performance should improve under such a
configuration.

Signed-off-by: default avatarAlexander Duyck <alexander.h.duyck@redhat.com>
Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
parent a8557d32

include/linux/virtio_ring.h

+4 −19
Original line number Diff line number Diff line
@@ -21,19 +21,20 @@ 
 * actually quite cheap.

 */



#ifdef CONFIG_SMP

static inline void virtio_mb(bool weak_barriers)

{

#ifdef CONFIG_SMP

	if (weak_barriers)

		smp_mb();

	else

#endif

		mb();

}



static inline void virtio_rmb(bool weak_barriers)

{

	if (weak_barriers)

		smp_rmb();

		dma_rmb();

	else

		rmb();

}
@@ -41,26 +42,10 @@ static inline void virtio_rmb(bool weak_barriers) 
static inline void virtio_wmb(bool weak_barriers)

{

	if (weak_barriers)

		smp_wmb();

		dma_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;