From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [PATCH v2] drivers: net: xgene: fix: Out of order descriptor bytes read Date: Fri, 30 Jan 2015 18:24:53 -0800 (PST) Message-ID: <20150130.182453.1030337100939592336.davem@davemloft.net> References: <1422571103-17497-1-git-send-email-isubramanian@apm.com> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, mlangsdo@redhat.com, patches@apm.com, eric.dumazet@gmail.com, kchudgar@apm.com To: isubramanian@apm.com Return-path: In-Reply-To: <1422571103-17497-1-git-send-email-isubramanian@apm.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org From: Iyappan Subramanian Date: Thu, 29 Jan 2015 14:38:23 -0800 > This patch fixes the following kernel crash, ... > Software writes poison data into the descriptor bytes[15:8] and upon > receiving the interrupt, if those bytes are overwritten by the hardware with > the valid data, software also reads bytes[7:0] and executes receive/tx > completion logic. > > If the CPU executes the above two reads in out of order fashion, then the > bytes[7:0] will have older data and causing the kernel panic. We have to > force the order of the reads and thus this patch introduces read memory > barrier between these reads. > > Signed-off-by: Iyappan Subramanian > Signed-off-by: Keyur Chudgar Applied, thanks.