Revert "virtio_ring: Update weak barriers to use dma_wmb/rmb"
This reverts commit 9e1a27ea42691429e31f158cce6fc61bc79bb2e9. 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>
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@ -21,20 +21,19 @@
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* actually quite cheap.
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*/
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#ifdef CONFIG_SMP
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static inline void virtio_mb(bool weak_barriers)
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{
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#ifdef CONFIG_SMP
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if (weak_barriers)
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smp_mb();
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else
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#endif
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mb();
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}
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static inline void virtio_rmb(bool weak_barriers)
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{
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if (weak_barriers)
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dma_rmb();
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smp_rmb();
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else
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rmb();
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}
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@ -42,10 +41,26 @@ static inline void virtio_rmb(bool weak_barriers)
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static inline void virtio_wmb(bool weak_barriers)
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{
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if (weak_barriers)
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dma_wmb();
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smp_wmb();
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else
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wmb();
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}
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#else
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static inline void virtio_mb(bool weak_barriers)
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{
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mb();
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}
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static inline void virtio_rmb(bool weak_barriers)
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{
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rmb();
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}
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static inline void virtio_wmb(bool weak_barriers)
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{
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wmb();
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}
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#endif
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struct virtio_device;
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struct virtqueue;
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