From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1423273AbcBZVfj (ORCPT ); Fri, 26 Feb 2016 16:35:39 -0500 Received: from p3plsmtps2ded01.prod.phx3.secureserver.net ([208.109.80.58]:54009 "EHLO p3plsmtps2ded01.prod.phx3.secureserver.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755452AbcBZVfG (ORCPT ); Fri, 26 Feb 2016 16:35:06 -0500 x-originating-ip: 72.167.245.219 From: "K. Y. Srinivasan" To: gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, devel@linuxdriverproject.org, olaf@aepfle.de, apw@canonical.com, vkuznets@redhat.com, jasowang@redhat.com Cc: "K. Y. Srinivasan" Subject: [PATCH 4/8] Drivers: hv: vmbus: avoid unneeded compiler optimizations in vmbus_wait_for_unload() Date: Fri, 26 Feb 2016 15:13:18 -0800 Message-Id: <1456528402-21982-4-git-send-email-kys@microsoft.com> X-Mailer: git-send-email 1.7.4.1 In-Reply-To: <1456528402-21982-1-git-send-email-kys@microsoft.com> References: <1456528381-21943-1-git-send-email-kys@microsoft.com> <1456528402-21982-1-git-send-email-kys@microsoft.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-CMAE-Envelope: MS4wfCPtwJSyjDQQuOls0f4n99U3a7R7o7jXL7WnEfMZDo8dO/oSM56g/1gg4qe2L+eokbUFHLVwJaQtiL6cgDbM9Hparg6/HQjEyQB7b5ltkWuALuWxLdc+ 2oLucegHqXQcfBXKTh1TklwqvKHWgPYfk+3M/TMiyJP0oyvO0iizq3Zp489X6kUqioFbwTRo3XJzVcP6O9KxF6cW3hXMUOt5wLHQ1iVRjXLWw7QlOKRwnFHw IYsLLJKZ1gQc7+Y1UDz4bd80yKvxvZF0dCsCXAufRizl4xPQZLrs5HCjELQJQGj5g/x9XptZ6lpHCrYdpNJSRHtfeFFbipt3bpLkHjgHlTqTtJfH7BEdbbjY hrfXH3LYCB8Zz8JMjOAF6cCslBUmqdWQQtrPez++bdOezPX4eVD2+u5ziaP9wrFk9NO/2WWv Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Vitaly Kuznetsov Message header is modified by the hypervisor and we read it in a loop, we need to prevent compilers from optimizing accesses. There are no such optimizations at this moment, this is just a future proof. Suggested-by: Radim Krcmar Signed-off-by: Vitaly Kuznetsov Reviewed-by: Radim Kr.má Signed-off-by: K. Y. Srinivasan --- drivers/hv/channel_mgmt.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-) diff --git a/drivers/hv/channel_mgmt.c b/drivers/hv/channel_mgmt.c index 73a17be..38b682ba 100644 --- a/drivers/hv/channel_mgmt.c +++ b/drivers/hv/channel_mgmt.c @@ -605,7 +605,7 @@ static void vmbus_wait_for_unload(void) bool unloaded = false; while (1) { - if (msg->header.message_type == HVMSG_NONE) { + if (READ_ONCE(msg->header.message_type) == HVMSG_NONE) { mdelay(10); continue; } -- 1.7.4.1