From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758763Ab3EFVGf (ORCPT ); Mon, 6 May 2013 17:06:35 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:59122 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756616Ab3EFUq1 (ORCPT ); Mon, 6 May 2013 16:46:27 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, "K. Y. Srinivasan" , Haiyang Zhang , Olaf Hering Subject: [ 048/115] Drivers: hv: vmbus: Fix a bug in hv_need_to_signal() Date: Mon, 6 May 2013 13:44:44 -0700 Message-Id: <20130506203100.485848515@linuxfoundation.org> X-Mailer: git-send-email 1.8.3.rc0.20.gb99dd2e In-Reply-To: <20130506203055.537199268@linuxfoundation.org> References: <20130506203055.537199268@linuxfoundation.org> User-Agent: quilt/0.60-5.1.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: "K. Y. Srinivasan" commit 288fa3e022eb85fa151e0f9bcd15caeb81679af6 upstream. As part of updating the vmbus protocol, the function hv_need_to_signal() was introduced. This functions helps optimize signalling from guest to host. The newly added memory barrier is needed to ensure that we correctly decide when to signal the host. Signed-off-by: K. Y. Srinivasan Reviewed-by: Haiyang Zhang Reported-by: Olaf Hering Signed-off-by: Greg Kroah-Hartman --- drivers/hv/ring_buffer.c | 1 + 1 file changed, 1 insertion(+) --- a/drivers/hv/ring_buffer.c +++ b/drivers/hv/ring_buffer.c @@ -71,6 +71,7 @@ u32 hv_end_read(struct hv_ring_buffer_in static bool hv_need_to_signal(u32 old_write, struct hv_ring_buffer_info *rbi) { + smp_mb(); if (rbi->ring_buffer->interrupt_mask) return false;