From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753017AbcKGNvL (ORCPT ); Mon, 7 Nov 2016 08:51:11 -0500 Received: from mout.kundenserver.de ([212.227.17.24]:57824 "EHLO mout.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752427AbcKGNvG (ORCPT ); Mon, 7 Nov 2016 08:51:06 -0500 From: Arnd Bergmann To: linux-arm-kernel@lists.infradead.org Cc: Christophe JAILLET , gregkh@linuxfoundation.org, jslaby@suse.com, baohua@kernel.org, kernel-janitors@vger.kernel.org, linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] serial: sirf: Simplify a test Date: Mon, 07 Nov 2016 14:50:27 +0100 Message-ID: <2916662.De1FDumaQl@wuerfel> User-Agent: KMail/5.1.3 (Linux/4.4.0-34-generic; KDE/5.18.0; x86_64; ; ) In-Reply-To: <20161101070333.12255-1-christophe.jaillet@wanadoo.fr> References: <20161101070333.12255-1-christophe.jaillet@wanadoo.fr> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" X-Provags-ID: V03:K0:fOLWJXt1zAzgOc6V4ZGCX6ZQRNEyD13dtq6wQZgrAOvFqbaemOn CpldtkbUGO0uV0ERdss5RnQfL0u46C/3c35lKXPlt0wWNyEKuM0KVP0/EW1i9GY+u2V4BYp iwi/xr4yNLFq0Yk3ano6g4f059EoPJNAY0ObU15wyOj6f2vWBb/b40QJCZ7s7UN0zIF+3ms +91/jbFxCtPpSWWdfEbgA== X-UI-Out-Filterresults: notjunk:1;V01:K0:OdlXptgQhVY=:PtDSy6e6xGDN66ytJgr8ZM 0fnp+LNhjjKS+WE4VLtX+Y3aemhiN4zsClnaYYkt9vqt+VC+fMZTl5LDXxhwKKmTNRN8rCV4d nIzldK9AIQLPwgcl52QgABvOEOYFs8Lp1mt0mZnKmcQgZyvMMw9N43Ri2cZfbM9Yah0fRCfV2 nXL1rYICCbU5+H3oERjx9wuhz8YPFOnouBPsKoR+Qj9Ur0b8Z81glMyratIJn8xmOUgoBV91S 74eduqcMzBqRsGN3kZQEglLPelfOgT/iFkPMkl0rpGpZDyVUruDG+KPKc5pscBGLFSjYbnE2D G2Y/p8oEh2RWESTtYiiWMxm9IAJh6iH+2hOklLKfjNLsABOYOyVyYBhgtcgKcu6b3SbrM6SpW 4MY3MgdqBBa8xto9BCgqmFU+ccTZJdl4nXkTok74Wbpy8fZkbtA5OTfQmei/bzEu18CSXgU9Q fWjvaywSXDVZvnzqY2G1ZGtO3yWGIvOhzz54jmcIQCu/UTXM4goMiqA0LXPGPWoCLpMjCF3Vu goMIzMTyXFEtwz5rIoupvf1ZGL3+VLMJyzqlBL0TTQXrjDP/JOWkaOdQ9RA7WV0gasJDlfo2h pB9e41SZVP8NgNAKXKjnKk9BMRtRYtS+CdeEG5Lw//oP5p5Ojgds0LmE5g4SjfxmwioaNTWcL jRjuF16+rjg9TumqEAhZNAauWIkaIG44hl/4Vv0Zn+ILPUZ4ZbAk0WdsNQshSSNoj4r9JDaKE SBihFjH6dyZKTKcI Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tuesday, November 1, 2016 8:03:33 AM CET Christophe JAILLET wrote: > 'dmaengine_prep_dma_cyclic()' does not return an error pointer, so the test > can be simplified to be more consistent. > > Signed-off-by: Christophe JAILLET The change looks correct in principle. It would be good to automate looking for other instances of this bug. How did you find it? Do you have e.g. a coccinelle script or did you just stumble over the issue by accident? There is one problem with your patch: > drivers/tty/serial/sirfsoc_uart.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/tty/serial/sirfsoc_uart.c b/drivers/tty/serial/sirfsoc_uart.c > index b186c9c4f850..666ca3156961 100644 > --- a/drivers/tty/serial/sirfsoc_uart.c > +++ b/drivers/tty/serial/sirfsoc_uart.c > @@ -609,7 +609,7 @@ static void sirfsoc_uart_start_next_rx_dma(struct uart_port *port) > sirfport->rx_dma_items.dma_addr, SIRFSOC_RX_DMA_BUF_SIZE, > SIRFSOC_RX_DMA_BUF_SIZE / 2, > DMA_DEV_TO_MEM, DMA_PREP_INTERRUPT); > - if (IS_ERR_OR_NULL(sirfport->rx_dma_items.desc)) { > + if (!sirfport->rx_dma_items.desc) { > dev_err(port->dev, "DMA slave single fail\n"); > return; > } The serial driver is for the sirf platform, which uses the sirf-dma dmaengine driver, and that particular driver has an incorrect dma_prep_cyclic implementation, so I think we also need this fix: diff --git a/drivers/dma/sirf-dma.c b/drivers/dma/sirf-dma.c index 8f62edad51be..220c611c89ae 100644 --- a/drivers/dma/sirf-dma.c +++ b/drivers/dma/sirf-dma.c @@ -775,7 +775,7 @@ sirfsoc_dma_prep_cyclic(struct dma_chan *chan, dma_addr_t addr, * BUFB */ if (buf_len != 2 * period_len) - return ERR_PTR(-EINVAL); + return NULL; /* Get free descriptor */ spin_lock_irqsave(&schan->lock, iflags); Arnd