From d45faaeedb762a3965a0246cf831e55045dd6ef8 Mon Sep 17 00:00:00 2001 From: "K. Y. Srinivasan" 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 Signed-off-by: Greg Kroah-Hartman --- 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 544362c6a9ca..6ea1b552cc8a 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