Commit a6596127 authored by Michael S. Tsirkin's avatar Michael S. Tsirkin
Browse files

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: default avatarMichael S. Tsirkin <mst@redhat.com>
Acked-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
parent d307fb16

include/linux/virtio_ring.h

+4 −21
Original line number Diff line number Diff line
@@ -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;

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