drivers: hv: switch to use mb() instead of smp_mb()
Even if guest were compiled without SMP support, it could not assume that host wasn't. So switch to use mb() instead of smp_mb() to force memory barriers for UP guest. Signed-off-by: Jason Wang <jasowang@redhat.com> Cc: Haiyang Zhang <haiyangz@microsoft.com> Cc: stable <stable@vger.kernel.org> Signed-off-by: K. Y. Srinivasan <kys@microsoft.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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@ -32,7 +32,7 @@
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void hv_begin_read(struct hv_ring_buffer_info *rbi)
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{
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rbi->ring_buffer->interrupt_mask = 1;
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smp_mb();
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mb();
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}
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u32 hv_end_read(struct hv_ring_buffer_info *rbi)
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@ -41,7 +41,7 @@ u32 hv_end_read(struct hv_ring_buffer_info *rbi)
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u32 write;
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rbi->ring_buffer->interrupt_mask = 0;
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smp_mb();
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mb();
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/*
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* Now check to see if the ring buffer is still empty.
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@ -71,7 +71,7 @@ u32 hv_end_read(struct hv_ring_buffer_info *rbi)
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static bool hv_need_to_signal(u32 old_write, struct hv_ring_buffer_info *rbi)
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{
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smp_mb();
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mb();
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if (rbi->ring_buffer->interrupt_mask)
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return false;
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@ -442,7 +442,7 @@ int hv_ringbuffer_write(struct hv_ring_buffer_info *outring_info,
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sizeof(u64));
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/* Issue a full memory barrier before updating the write index */
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smp_mb();
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mb();
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/* Now, update the write location */
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hv_set_next_write_location(outring_info, next_write_location);
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@ -549,7 +549,7 @@ int hv_ringbuffer_read(struct hv_ring_buffer_info *inring_info, void *buffer,
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/* Make sure all reads are done before we update the read index since */
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/* the writer may start writing to the read area once the read index */
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/*is updated */
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smp_mb();
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mb();
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/* Update the read index */
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hv_set_next_read_location(inring_info, next_read_location);
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@ -434,7 +434,7 @@ static void vmbus_on_msg_dpc(unsigned long data)
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* will not deliver any more messages since there is
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* no empty slot
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*/
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smp_mb();
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mb();
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if (msg->header.message_flags.msg_pending) {
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/*
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