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Commit d45faaee authored by K. Y. Srinivasan's avatar K. Y. Srinivasan Committed by Greg Kroah-Hartman
Browse files

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: default avatarK. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent a6341f00

drivers/hv/ring_buffer.c

+3 −3
Original line number Diff line number Diff line
@@ -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;