From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 08314C3A5A6 for ; Thu, 19 Sep 2019 10:28:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D032721907 for ; Thu, 19 Sep 2019 10:28:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731984AbfISK2A (ORCPT ); Thu, 19 Sep 2019 06:28:00 -0400 Received: from metis.ext.pengutronix.de ([85.220.165.71]:52961 "EHLO metis.ext.pengutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730905AbfISK17 (ORCPT ); Thu, 19 Sep 2019 06:27:59 -0400 Received: from kresse.hi.pengutronix.de ([2001:67c:670:100:1d::2a]) by metis.ext.pengutronix.de with esmtp (Exim 4.92) (envelope-from ) id 1iAtfK-0005Fo-Jo; Thu, 19 Sep 2019 12:27:58 +0200 Message-ID: <7d694da8ffe098c6c8f6fe9c3a2306fda55eb655.camel@pengutronix.de> Subject: Re: [PATCH v2 1/3] dmaengine: imx-sdma: fix buffer ownership From: Lucas Stach To: Philipp Puschmann , linux-kernel@vger.kernel.org Cc: yibin.gong@nxp.com, fugang.duan@nxp.com, dan.j.williams@intel.com, vkoul@kernel.org, shawnguo@kernel.org, s.hauer@pengutronix.de, kernel@pengutronix.de, festevam@gmail.com, linux-imx@nxp.com, dmaengine@vger.kernel.org, linux-arm-kernel@lists.infradead.org Date: Thu, 19 Sep 2019 12:27:58 +0200 In-Reply-To: <20190919102319.23368-2-philipp.puschmann@emlix.com> References: <20190911144943.21554-1-philipp.puschmann@emlix.com> <20190919102319.23368-1-philipp.puschmann@emlix.com> <20190919102319.23368-2-philipp.puschmann@emlix.com> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.30.5-1.1 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-SA-Exim-Connect-IP: 2001:67c:670:100:1d::2a X-SA-Exim-Mail-From: l.stach@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-kernel@vger.kernel.org Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Philipp, On Do, 2019-09-19 at 12:23 +0200, Philipp Puschmann wrote: > BD_DONE flag marks ownership of the buffer. When 1 SDMA owns the > buffer, when 0 ARM owns it. When processing the buffers in > sdma_update_channel_loop the ownership of the currently processed > buffer was set to SDMA again before running the callback function of > the buffer and while the sdma script may be running in parallel. So > there was the possibility to get the buffer overwritten by SDMA > before > it has been processed by kernel leading to kind of random errors in > the > upper layers, e.g. bluetooth. > > Signed-off-by: Philipp Puschmann > > --- > > Changelog v2: > - add dma_wb() > > drivers/dma/imx-sdma.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/drivers/dma/imx-sdma.c b/drivers/dma/imx-sdma.c > index 9ba74ab7e912..e029a2443cfc 100644 > --- a/drivers/dma/imx-sdma.c > +++ b/drivers/dma/imx-sdma.c > @@ -802,7 +802,6 @@ static void sdma_update_channel_loop(struct > sdma_channel *sdmac) > */ > > desc->chn_real_count = bd->mode.count; > - bd->mode.status |= BD_DONE; > bd->mode.count = desc->period_len; > desc->buf_ptail = desc->buf_tail; > desc->buf_tail = (desc->buf_tail + 1) % desc->num_bd; > @@ -817,6 +816,9 @@ static void sdma_update_channel_loop(struct > sdma_channel *sdmac) > dmaengine_desc_get_callback_invoke(&desc->vd.tx, NULL); > spin_lock(&sdmac->vc.lock); > > + dma_wb(); Has this change been tested? The function you want here is called dma_wmb(). Regards, Lucas > + bd->mode.status |= BD_DONE; > + > if (error) > sdmac->status = old_status; > }