drivers: hv: switch to use mb() instead of smp_mb()

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>

diff --git a/drivers/hv/ring_buffer.c b/drivers/hv/ring_buffer.c
index 8af25a0..d01edf3 100644 (file)
--- a/drivers/hv/ring_buffer.c
+++ b/drivers/hv/ring_buffer.c
@@ -383,7 +383,7 @@ int hv_ringbuffer_write(struct hv_ring_buffer_info *outring_info,
                                             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_buffer_info *inring_info, void *buffer,
        /* 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);

diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index a220e57..10619b3 100644 (file)
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -466,7 +466,7 @@ static void vmbus_on_msg_dpc(unsigned long data)
                 * will not deliver any more messages since there is
                 * no empty slot
                 */
-               smp_mb();
+               mb();
 
                if (msg->header.message_flags.msg_pending) {
                        /*