Revert "virtio_ring: Update weak barriers to use dma_wmb/rmb" (d307fb16) · Commits · 戴 / test

This reverts commit . While that commit optimizes !CONFIG_SMP, it mixes up DMA and SMP concepts, making the code hard to figure out. A better way to optimize this is with the new __smp_XXX barriers. As a first step, go back to full rmb/wmb barriers for !SMP. We switch to __smp_XXX barriers in the next patch. 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>

include/linux/virtio_ring.h

+19 −4

Original line number	Diff line number	Diff line
		@@ -21,20 +21,19 @@
		* 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)
		dma_rmb();
		smp_rmb();
		else
		rmb();
		}
		@@ -42,10 +41,26 @@ static inline void virtio_rmb(bool weak_barriers)
		static inline void virtio_wmb(bool weak_barriers)
		{
		if (weak_barriers)
		dma_wmb();
		smp_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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