From e91e84fa4cfeb67a9a096f1adaa1a1a692474724 Mon Sep 17 00:00:00 2001 From: Jason Wang Date: Thu, 20 Jun 2013 12:58:57 +0800 Subject: [PATCH] drivers: hv: check interrupt mask before read_index This patches add a read barriers to force the driver to check the interrupt mask before read_index. Otherwise we may lost a kick to host. Cc: K. Y. Srinivasan Cc: Haiyang Zhang Signed-off-by: Jason Wang Signed-off-by: K. Y. Srinivasan Signed-off-by: Greg Kroah-Hartman --- drivers/hv/ring_buffer.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/hv/ring_buffer.c b/drivers/hv/ring_buffer.c index 791f45dfc85d..26c93cf9f6be 100644 --- a/drivers/hv/ring_buffer.c +++ b/drivers/hv/ring_buffer.c @@ -75,6 +75,8 @@ static bool hv_need_to_signal(u32 old_write, struct hv_ring_buffer_info *rbi) if (rbi->ring_buffer->interrupt_mask) return false; + /* check interrupt_mask before read_index */ + rmb(); /* * This is the only case we need to signal when the * ring transitions from being empty to non-empty. -- 2.30.2