Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761516AbXKOGyz (ORCPT ); Thu, 15 Nov 2007 01:54:55 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932442AbXKOGqz (ORCPT ); Thu, 15 Nov 2007 01:46:55 -0500 Received: from pentafluge.infradead.org ([213.146.154.40]:57861 "EHLO pentafluge.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1762876AbXKOGqx (ORCPT ); Thu, 15 Nov 2007 01:46:53 -0500 Date: Wed, 14 Nov 2007 22:44:18 -0800 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org, stable@kernel.org Cc: Justin Forbes , Zwane Mwaikambo , "Theodore Ts'o" , Randy Dunlap , Dave Jones , Chuck Wolber , Chris Wedgwood , Michael Krufky , Chuck Ebbert , Domenico Andreoli , torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Roland Dreier Subject: [patch 08/40] IB/mthca: Use mmiowb() to avoid firmware commands getting jumbled up Message-ID: <20071115064418.GI19218@kroah.com> References: <20071115062710.885284510@mini.kroah.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline; filename="ib-mthca-use-mmiowb-to-avoid-firmware-commands-getting-jumbled-up.patch" In-Reply-To: <20071115064302.GA19218@kroah.com> User-Agent: Mutt/1.5.16 (2007-06-09) X-Bad-Reply: References and In-Reply-To but no 'Re:' in Subject. Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1624 Lines: 47 -stable review patch. If anyone has any objections, please let us know. ------------------ From: Roland Dreier Upstream as 76d7cc0345a037e8eea426f8abc710abd22946dd Firmware commands are sent to the HCA by writing multiple words to a command register block. Access to this block of registers is serialized with a mutex. However, on large SGI systems, problems were seen with multiple CPUs issuing FW commands at the same time, because the writes to the register block may be reordered within the system interconnect and reach the HCA in a different order than they were issued (even with the mutex). Fix this by adding an mmiowb() before dropping the mutex. Tested-by: Arthur Kepner Signed-off-by: Roland Dreier Signed-off-by: Greg Kroah-Hartman --- drivers/infiniband/hw/mthca/mthca_cmd.c | 6 ++++++ 1 file changed, 6 insertions(+) --- a/drivers/infiniband/hw/mthca/mthca_cmd.c +++ b/drivers/infiniband/hw/mthca/mthca_cmd.c @@ -290,6 +290,12 @@ static int mthca_cmd_post(struct mthca_d err = mthca_cmd_post_hcr(dev, in_param, out_param, in_modifier, op_modifier, op, token, event); + /* + * Make sure that our HCR writes don't get mixed in with + * writes from another CPU starting a FW command. + */ + mmiowb(); + mutex_unlock(&dev->cmd.hcr_mutex); return err; } -- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/