Drivers: hv: vmbus: Use READ_ONCE() to read variables that are volatile

Use the READ_ONCE macro to access variabes that can change asynchronously.
This is the recommended mechanism for dealing with "unsafe" compiler
optimizations.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.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 544362c..6ea1b55 100644 (file)
--- a/drivers/hv/ring_buffer.c
+++ b/drivers/hv/ring_buffer.c
@@ -69,7 +69,7 @@ u32 hv_end_read(struct hv_ring_buffer_info *rbi)
 static bool hv_need_to_signal(u32 old_write, struct hv_ring_buffer_info *rbi)
 {
        mb();
-       if (rbi->ring_buffer->interrupt_mask)
+       if (READ_ONCE(rbi->ring_buffer->interrupt_mask))
                return false;
 
        /* check interrupt_mask before read_index */
@@ -78,7 +78,7 @@ static bool hv_need_to_signal(u32 old_write, struct hv_ring_buffer_info *rbi)
         * This is the only case we need to signal when the
         * ring transitions from being empty to non-empty.
         */
-       if (old_write == rbi->ring_buffer->read_index)
+       if (old_write == READ_ONCE(rbi->ring_buffer->read_index))
                return true;
 
        return false;
@@ -117,7 +117,7 @@ static bool hv_need_to_signal_on_read(struct hv_ring_buffer_info *rbi)
         */
        mb();
 
-       pending_sz = rbi->ring_buffer->pending_send_sz;
+       pending_sz = READ_ONCE(rbi->ring_buffer->pending_send_sz);
        /* If the other end is not blocked on write don't bother. */
        if (pending_sz == 0)
                return false;