[PATCH 3.4 157/214] drivers: hv: switch to use mb() instead of smp_mb()

Greg Kroah-Hartman
2014-06-05T04:21:51Z

From: Jason Wang <jasowang@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 <jasowang@redhat.com>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[bwh: Backported to 3.2:
- Drop changes to functions that don't exist here
- hv_ringbuffer_write() has only a write memory barrier]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
[hq: Backported to 3.4:
- Add the change in hv_ringbuffer_read]
Signed-off-by: Qiang Huang <h.huangqiang@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/hv/ring_buffer.c | 4 ++--
drivers/hv/vmbus_drv.c | 2 +-
2 files changed, 3 insertions(+), 3 deletions(-)

--- a/drivers/hv/ring_buffer.c
+++ b/drivers/hv/ring_buffer.c
@@ -383,7 +383,7 @@ int hv_ringbuffer_write(struct hv_ring_b
sizeof(u64));

/* Make sure we flush all writes before updating the writeIndex */
- smp_wmb();
+ wmb();

/* Now, update the write location */
hv_set_next_write_location(outring_info, next_write_location);
@@ -485,7 +485,7 @@ 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
@@ -466,7 +466,7 @@ 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) {
/*