From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752815AbcD1PMs (ORCPT ); Thu, 28 Apr 2016 11:12:48 -0400 Received: from mail-wm0-f49.google.com ([74.125.82.49]:38703 "EHLO mail-wm0-f49.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752692AbcD1PMr (ORCPT ); Thu, 28 Apr 2016 11:12:47 -0400 Message-ID: <5722283C.60209@gmail.com> Date: Thu, 28 Apr 2016 17:11:56 +0200 From: Vyacheslav Yurkov User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.1.0 MIME-Version: 1.0 To: Andrey Gursky CC: linux-kernel@vger.kernel.org, Greg Kroah-Hartman Subject: Re: [PATCH] drivers/base: wrong return value of dmam_declare_coherent_memory References: <20160428163128.2670db58033e598779e373f6@e-mail.ua> In-Reply-To: <20160428163128.2670db58033e598779e373f6@e-mail.ua> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 28.04.2016 16:31, Andrey Gursky wrote: > Vyacheslav, > > thanks for your patch. > > For now it introduces a new bug. > > Vyacheslav Yurkov gmail.com> writes: > >> >> Hi guys, >> I found an issue in managed version of dma_declare_coherent_memory, >> i.e. in dmam_declare_coherent_memory. It looks like the return value >> of dma_declare_coherent_memory is zero in case of error and a >> requested flag on success, > > You should take this into account and not ignore the value of rc at all > by using flags instead, which is not being altered by > dma_declare_coherent_memory() making the latter appear to succeed > always. > > Hi Andrey, Thanks for spotting this. My intention was to compare rc of course, not the flags. While thinking it over I came up with improved version, which is inlined below. --- Yours sincerely, Vyacheslav V. Yurkov P.S.: I'm not subscribed to the maillist, so please include me in CC when responding to this Email. --- --- linux-4.5.2/drivers/base/dma-mapping.c.orig 2016-04-20 08:46:35.000000000 +0200 +++ linux-4.5.2/drivers/base/dma-mapping.c 2016-04-28 16:55:13.211945276 +0200 @@ -198,10 +198,14 @@ int dmam_declare_coherent_memory(struct rc = dma_declare_coherent_memory(dev, phys_addr, device_addr, size, flags); - if (rc == 0) + + if ((rc & (DMA_MEMORY_MAP | DMA_MEMORY_IO)) != 0) { devres_add(dev, res); - else + rc = 0; + } else { devres_free(res); + rc = -ENOMEM; + } return rc; } Signed-off-by: Vyacheslav Yurkov