From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757672AbcDAAAU (ORCPT ); Thu, 31 Mar 2016 20:00:20 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:39375 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753150AbcDAAAS (ORCPT ); Thu, 31 Mar 2016 20:00:18 -0400 Date: Thu, 31 Mar 2016 17:00:17 -0700 From: Greg KH To: "K. Y. Srinivasan" Cc: linux-kernel@vger.kernel.org, devel@linuxdriverproject.org, olaf@aepfle.de, apw@canonical.com, vkuznets@redhat.com, jasowang@redhat.com, stable@vger.kernel.org Subject: Re: [PATCH 3/7] Drivers: hv: vmbus: Fix a bug in hv_need_to_signal_on_read() Message-ID: <20160401000017.GB10232@kroah.com> References: <1458780816-4328-1-git-send-email-kys@microsoft.com> <1458780837-4367-1-git-send-email-kys@microsoft.com> <1458780837-4367-3-git-send-email-kys@microsoft.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1458780837-4367-3-git-send-email-kys@microsoft.com> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Mar 23, 2016 at 05:53:53PM -0700, K. Y. Srinivasan wrote: > We need to issue a full memory barrier prior making a signalling decision. > > Signed-off-by: K. Y. Srinivasan > Cc: stable@vger.kernel.org > --- > drivers/hv/ring_buffer.c | 1 + > 1 files changed, 1 insertions(+), 0 deletions(-) > > diff --git a/drivers/hv/ring_buffer.c b/drivers/hv/ring_buffer.c > index 2919395..67dc245 100644 > --- a/drivers/hv/ring_buffer.c > +++ b/drivers/hv/ring_buffer.c > @@ -104,6 +104,7 @@ static bool hv_need_to_signal_on_read(struct hv_ring_buffer_info *rbi) > u32 cur_write_sz; > u32 pending_sz; > > + mb(); And, are you sure this is correct? You better document the heck out of this, why it's here, and what it is protecting. "raw" mb() calls are really rare for good reason. thanks, greg k-h