From patchwork Thu Aug 17 10:41:32 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Hans Verkuil X-Patchwork-Id: 13356241 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 171EFEB64DD for ; Thu, 17 Aug 2023 10:42:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1349961AbjHQKl6 (ORCPT ); Thu, 17 Aug 2023 06:41:58 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43998 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242143AbjHQKli (ORCPT ); Thu, 17 Aug 2023 06:41:38 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E68C52D5A; Thu, 17 Aug 2023 03:41:36 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 7B97E611D4; Thu, 17 Aug 2023 10:41:36 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id A568AC433C7; Thu, 17 Aug 2023 10:41:34 +0000 (UTC) Message-ID: Date: Thu, 17 Aug 2023 12:41:32 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.12.0 Content-Language: en-US, nl To: Linux Media Mailing List Cc: Marek Szyprowski , Tomasz Figa , Linux Kernel , Jan Kara , David Hildenbrand , Linus Torvalds From: Hans Verkuil Subject: [PATCH] media: vb2: frame_vector.c: replace WARN_ONCE with a comment Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org The WARN_ONCE was issued also in cases that had nothing to do with VM_IO (e.g. if the start address was just a random value and uaccess fails with -EFAULT). There are no reports of WARN_ONCE being issued for actual VM_IO cases, so just drop it and instead add a note to the comment before the function. Signed-off-by: Hans Verkuil Reviewed-by: David Hildenbrand Reported-by: Yikebaer Aizezi diff --git a/drivers/media/common/videobuf2/frame_vector.c b/drivers/media/common/videobuf2/frame_vector.c index 0f430ddc1f67..fd87747be9b1 100644 --- a/drivers/media/common/videobuf2/frame_vector.c +++ b/drivers/media/common/videobuf2/frame_vector.c @@ -31,6 +31,10 @@ * different type underlying the specified range of virtual addresses. * When the function isn't able to map a single page, it returns error. * + * Note that get_vaddr_frames() cannot follow VM_IO mappings. It used + * to be able to do that, but that could (racily) return non-refcounted + * pfns. + * * This function takes care of grabbing mmap_lock as necessary. */ int get_vaddr_frames(unsigned long start, unsigned int nr_frames, bool write, @@ -59,8 +63,6 @@ int get_vaddr_frames(unsigned long start, unsigned int nr_frames, bool write, if (likely(ret > 0)) return ret; - /* This used to (racily) return non-refcounted pfns. Let people know */ - WARN_ONCE(1, "get_vaddr_frames() cannot follow VM_IO mapping"); vec->nr_frames = 0; return ret ? ret : -EFAULT; }