3.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: Jason Wang <jasow...@redhat.com>
commit 35848f68b07df3f917cb13fc3c134718669f569b upstream.
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 <jasow...@redhat.com>
Cc: Haiyang Zhang <haiya...@microsoft.com>
Signed-off-by: K. Y. Srinivasan <k...@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
drivers/hv/ring_buffer.c | 10 +++++-----
drivers/hv/vmbus_drv.c | 2 +-
2 files changed, 6 insertions(+), 6 deletions(-)
--- a/drivers/hv/ring_buffer.c
+++ b/drivers/hv/ring_buffer.c
@@ -32,7 +32,7 @@
void hv_begin_read(struct hv_ring_buffer_info *rbi)
{
rbi->ring_buffer->interrupt_mask = 1;
- smp_mb();
+ mb();
}
u32 hv_end_read(struct hv_ring_buffer_info *rbi)
@@ -41,7 +41,7 @@ u32 hv_end_read(struct hv_ring_buffer_in
u32 write;
rbi->ring_buffer->interrupt_mask = 0;
- smp_mb();
+ mb();
/*
* Now check to see if the ring buffer is still empty.
@@ -71,7 +71,7 @@ u32 hv_end_read(struct hv_ring_buffer_in
static bool hv_need_to_signal(u32 old_write, struct hv_ring_buffer_info *rbi)
{
- smp_mb();
+ mb();
if (rbi->ring_buffer->interrupt_mask)
return false;
@@ -442,7 +442,7 @@ int hv_ringbuffer_write(struct hv_ring_b
sizeof(u64));
/* Issue a full memory barrier before updating the write index */
- smp_mb();
+ mb();
/* Now, update the write location */
hv_set_next_write_location(outring_info, next_write_location);
@@ -549,7 +549,7 @@ int hv_ringbuffer_read(struct hv_ring_bu
/* Make sure all reads are done before we update the read index since */
/* the writer may start writing to the read area once the read index */
/*is updated */
- smp_mb();
+ mb();
/* Update the read index */
hv_set_next_read_location(inring_info, next_read_location);
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -434,7 +434,7 @@ static void vmbus_on_msg_dpc(unsigned lo
* will not deliver any more messages since there is
* no empty slot
*/
- smp_mb();
+ mb();
if (msg->header.message_flags.msg_pending) {
/*
--
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