From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751927Ab3FTFJ2 (ORCPT ); Thu, 20 Jun 2013 01:09:28 -0400 Received: from mx1.redhat.com ([209.132.183.28]:34965 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751092Ab3FTFJ1 (ORCPT ); Thu, 20 Jun 2013 01:09:27 -0400 From: Jason Wang To: kys@microsoft.com, devel@linuxdriverproject.org, linux-kernel@vger.kernel.org, gregkh@linuxfoundation.org Cc: haiyangz@microsoft.com, Jason Wang Subject: [PATCH] drivers: hv: check interrupt mask before read_index Date: Thu, 20 Jun 2013 12:58:57 +0800 Message-Id: <1371704337-46108-1-git-send-email-jasowang@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 --- drivers/hv/ring_buffer.c | 2 ++ 1 files changed, 2 insertions(+), 0 deletions(-) diff --git a/drivers/hv/ring_buffer.c b/drivers/hv/ring_buffer.c index 791f45d..26c93cf 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. -- 1.7.1