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=-11.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 9A390C432BE for ; Tue, 17 Aug 2021 11:57:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8076060F38 for ; Tue, 17 Aug 2021 11:57:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239777AbhHQL5k (ORCPT ); Tue, 17 Aug 2021 07:57:40 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49576 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237001AbhHQL5j (ORCPT ); Tue, 17 Aug 2021 07:57:39 -0400 Received: from mail-pj1-x102a.google.com (mail-pj1-x102a.google.com [IPv6:2607:f8b0:4864:20::102a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 456E9C0613C1 for ; Tue, 17 Aug 2021 04:57:06 -0700 (PDT) Received: by mail-pj1-x102a.google.com with SMTP id oa17so31648315pjb.1 for ; Tue, 17 Aug 2021 04:57:06 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=5eVWcqoojYYHru/CT40TixXoXoJZblc78933GWI+qc4=; b=Z+URnrGA0iYXyqx0+EwysvNVtOVd/Qg1weNCKom9Cykq/vKnuc/3Ozg0SuDdh8H9Jl INx88aBuUSjXb+wrOFcWiXYtydeSGYZgbe7lq/4+OzyaYskq1ZNsFNjU63ZBOSFtNX2q sva2h9Tucj6yOM3qYeQPRZlfOV0RjZlGok/fc= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=5eVWcqoojYYHru/CT40TixXoXoJZblc78933GWI+qc4=; b=eCBnm5XfWsapemA1E0/02fXfcOR8UupYSN1OXhBqw5Cvjo0UP5IivYeyIqOj7k3Hpr 7w0lC3PFlGkubKjK9COg9aox5ZtVjO8eY2PMum7t6z+/D0c9m/h2nXN2j+b7IsoPArZQ UnICA2NdO7gdMhuqY9c26+fLXiY80FQTzb3KU4EFCucw5w8KwdFrJIKJqlQtnTOQJYUB yku1bzZhocfNcG/SCSDS3/2K9IwcLpPRFsgoiImBWq+n5w564yCHAYfdPLHG4NCWdMOf 2eLYrehmyHDwz1xqFAzeaxWNneWlUT7hAKFYmcURujlMEIXlYqCiJy9Ad/6F4GNJDqRH x/uw== X-Gm-Message-State: AOAM531YmCLwlb1j416msy1KcvUmzx2PaNQxsaBTiPEEBBrdM8gDK9rm 3N857gUN2L0q5yqYQdP4in8k/g== X-Google-Smtp-Source: ABdhPJyELtpHZ2cwJXA+46vVbt40ueVOgtpSjStycCk1fXsL7JKuECiBqUZZ+dxXVh6iLCDlkTKYGw== X-Received: by 2002:a17:902:f688:b0:12d:7aa6:1e44 with SMTP id l8-20020a170902f68800b0012d7aa61e44mr2773102plg.8.1629201425796; Tue, 17 Aug 2021 04:57:05 -0700 (PDT) Received: from google.com ([2409:10:2e40:5100:8aab:cb84:5fe8:99dd]) by smtp.gmail.com with ESMTPSA id y5sm2200275pjy.37.2021.08.17.04.57.02 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 17 Aug 2021 04:57:05 -0700 (PDT) Date: Tue, 17 Aug 2021 20:56:59 +0900 From: Sergey Senozhatsky To: Hans Verkuil Cc: Sergey Senozhatsky , Tomasz Figa , Dafna Hirschfeld , Ricardo Ribalda , Christoph Hellwig , Mauro Carvalho Chehab , linux-media@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCHv4 8/8] videobuf2: handle non-contiguous DMA allocations Message-ID: References: <20210727070517.443167-1-senozhatsky@chromium.org> <20210727070517.443167-9-senozhatsky@chromium.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On (21/08/03 12:15), Hans Verkuil wrote: > > static void *vb2_dc_vaddr(struct vb2_buffer *vb, void *buf_priv) > > { > > struct vb2_dc_buf *buf = buf_priv; > > - struct dma_buf_map map; > > - int ret; > > > > - if (!buf->vaddr && buf->db_attach) { > > - ret = dma_buf_vmap(buf->db_attach->dmabuf, &map); > > - buf->vaddr = ret ? NULL : map.vaddr; > > + if (buf->vaddr) > > + return buf->vaddr; > > + > > + if (buf->db_attach) { > > + struct dma_buf_map map; > > + > > + if (!dma_buf_vmap(buf->db_attach->dmabuf, &map)) > > + buf->vaddr = map.vaddr; > > + > > + return buf->vaddr; > > } > > > > + if (!buf->coherent_mem) > > + buf->vaddr = dma_vmap_noncontiguous(buf->dev, buf->size, > > + buf->dma_sgt); > > return buf->vaddr; > > } > > This function really needs a bunch of comments. > > What I want to see here specifically is under which circumstances this function > can return NULL. > > - dma_buf_vmap returns an error > - for non-coherent memory dma_vmap_noncontiguous returns an error > - coherent memory with DMA_ATTR_NO_KERNEL_MAPPING set. OK, I added some comments. > In the latter case, if a buffer with coherent memory and DMA_ATTR_NO_KERNEL_MAPPING > is exported as a dma_buf, and dma_buf_vmap is called by the importer of this dma-buf, > what happens then? I think that in that case dma_buf_vmap should return an error? Should we error out in vb2_dc_vaddr() in this case? --- diff --git a/drivers/media/common/videobuf2/videobuf2-dma-contig.c b/drivers/media/common/videobuf2/videobuf2-dma-contig.c index d4089d0b5ec5..e1d8ae1548fa 100644 --- a/drivers/media/common/videobuf2/videobuf2-dma-contig.c +++ b/drivers/media/common/videobuf2/videobuf2-dma-contig.c @@ -102,6 +102,9 @@ static void *vb2_dc_vaddr(struct vb2_buffer *vb, void *buf_priv) if (buf->db_attach) { struct dma_buf_map map; + if (WARN_ON(buf->attrs & DMA_ATTR_NO_KERNEL_MAPPING)) + return NULL; + if (!dma_buf_vmap(buf->db_attach->dmabuf, &map)) buf->vaddr = map.vaddr; --- [..] > > @@ -362,7 +451,7 @@ static int vb2_dc_dmabuf_ops_vmap(struct dma_buf *dbuf, struct dma_buf_map *map) > > { > > struct vb2_dc_buf *buf = dbuf->priv; > > > > - dma_buf_map_set_vaddr(map, buf->vaddr); > > + dma_buf_map_set_vaddr(map, vb2_dc_vaddr(buf->vb, buf)); > > vb2_dc_vaddr() can return NULL, shouldn't this function return an error in that case? Done, thanks. > BTW, looking at where vb2_plane_vaddr() is called in drivers I notice that most (all?) > drivers do not check for NULL. Somewhat scary, to be honest. That's a separate issue, though. I may have some time in the future and can add missing if-s to the drivers.