From d45faaeedb762a3965a0246cf831e55045dd6ef8 Mon Sep 17 00:00:00 2001
From: "K. Y. Srinivasan" <kys@microsoft.com>
Date: Sat, 2 Apr 2016 17:59:47 -0700
Subject: [PATCH] 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>
---
drivers/hv/ring_buffer.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/drivers/hv/ring_buffer.c b/drivers/hv/ring_buffer.c
index 544362c6a9cac..6ea1b552cc8a1 100644
--- 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;
--
2.30.2