From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752249AbeDJRGR (ORCPT ); Tue, 10 Apr 2018 13:06:17 -0400 Received: from verein.lst.de ([213.95.11.211]:45472 "EHLO newverein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752078AbeDJRGQ (ORCPT ); Tue, 10 Apr 2018 13:06:16 -0400 Date: Tue, 10 Apr 2018 19:06:15 +0200 From: Christoph Hellwig To: Takashi Iwai Cc: Christoph Hellwig , Christian =?iso-8859-1?Q?K=F6nig?= , Konrad Rzeszutek Wilk , iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] swiotlb: Fix unexpected swiotlb_alloc_coherent() failures Message-ID: <20180410170615.GA27589@lst.de> References: <20180410170513.22834-1-tiwai@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180410170513.22834-1-tiwai@suse.de> User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Apr 10, 2018 at 07:05:13PM +0200, Takashi Iwai wrote: > The code refactoring by commit 0176adb00406 ("swiotlb: refactor > coherent buffer allocation") made swiotlb_alloc_buffer() almost always > failing due to a thinko: namely, the function evaluates the > dma_coherent_ok() call incorrectly and dealing as if it's invalid. > This ends up with weird errors like iwlwifi probe failure or amdgpu > screen flickering. > > This patch corrects the logic error. This looks ok, although even hitting this code is a bad sign. Do you know why the previous dma_direct_alloc didn't succeed? > > Bugzilla: https://bugzilla.suse.com/show_bug.cgi?id=1088658 > Bugzilla: https://bugzilla.suse.com/show_bug.cgi?id=1088902 > Fixes: 0176adb00406 ("swiotlb: refactor coherent buffer allocation") > Cc: # v4.16+ > Signed-off-by: Takashi Iwai > --- > lib/swiotlb.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/lib/swiotlb.c b/lib/swiotlb.c > index 47aeb04c1997..de7cc540450f 100644 > --- a/lib/swiotlb.c > +++ b/lib/swiotlb.c > @@ -719,7 +719,7 @@ swiotlb_alloc_buffer(struct device *dev, size_t size, dma_addr_t *dma_handle, > goto out_warn; > > *dma_handle = __phys_to_dma(dev, phys_addr); > - if (dma_coherent_ok(dev, *dma_handle, size)) > + if (!dma_coherent_ok(dev, *dma_handle, size)) > goto out_unmap; > > memset(phys_to_virt(phys_addr), 0, size); > -- > 2.16.3 ---end quoted text---