From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754043AbaHDROW (ORCPT ); Mon, 4 Aug 2014 13:14:22 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:56478 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751770AbaHDQty (ORCPT ); Mon, 4 Aug 2014 12:49:54 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Christoph Hellwig" , "Nathan Fontenot" , "Brian King" Date: Mon, 04 Aug 2014 17:48:31 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 13/94] ibmvscsi: Add memory barriers for send / receive In-Reply-To: X-SA-Exim-Connect-IP: 192.168.4.249 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.2.62-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Brian King commit 7114aae02742d6b5c5a0d39a41deb61d415d3717 upstream. Add a memory barrier prior to sending a new command to the VIOS to ensure the VIOS does not receive stale data in the command buffer. Also add a memory barrier when processing the CRQ for completed commands. Signed-off-by: Brian King Acked-by: Nathan Fontenot Signed-off-by: Christoph Hellwig [bwh: Backported to 3.2: as the iSeries code is still present, these functions have different names and live in rpa_vscsi.c.] Signed-off-by: Ben Hutchings --- drivers/scsi/ibmvscsi/ibmvscsi.c | 10 ++++++++++ 1 file changed, 10 insertions(+) --- a/drivers/scsi/ibmvscsi/rpa_vscsi.c +++ b/drivers/scsi/ibmvscsi/rpa_vscsi.c @@ -104,6 +104,11 @@ static struct viosrp_crq *crq_queue_next if (crq->valid & 0x80) { if (++queue->cur == queue->size) queue->cur = 0; + + /* Ensure the read of the valid bit occurs before reading any + * other bits of the CRQ entry + */ + rmb(); } else crq = NULL; spin_unlock_irqrestore(&queue->lock, flags); @@ -122,6 +127,11 @@ static int rpavscsi_send_crq(struct ibmv { struct vio_dev *vdev = to_vio_dev(hostdata->dev); + /* + * Ensure the command buffer is flushed to memory before handing it + * over to the VIOS to prevent it from fetching any stale data. + */ + mb(); return plpar_hcall_norets(H_SEND_CRQ, vdev->unit_address, word1, word2); }