From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5D53A606A326 for ; Fri, 6 Nov 2026 13:32:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=SMX0mLEl Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id B4206112D67; Fri, 6 Nov 2026 13:32:16 +0000 (UTC) Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by gabe.freedesktop.org (Postfix) with ESMTPS id 31490112D67 for ; Fri, 6 Nov 2026 13:32:10 +0000 (UTC) Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id EEDC741A84 for ; Fri, 6 Nov 2026 13:32:09 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id AA2C61F0089F; Fri, 6 Nov 2026 13:32:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793971929; bh=LrFYHDu+0cgUyqOZLejxo7bDM4Z0LD9eaDc6yWVPixc=; h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=SMX0mLElZ/m2K8FZJOF9gV35NIbASr9aUYV+3bEUVCBT0T/M7ajfdef8zXttkbYdy K987qWReKDjzZONSqt25roUJ15xXlEtUL6/oMwxY4TMnGUEYUprGZ2PJaY6IWNFHtB MCVw/BxJWtNRfnmOUtSOEm7ncw7q/Sx/2D+zP+oBtlcwlPRBfcfInKvyq0MYZKTm8H +eoUMftH1iR5YWvE/hl7OE7IL6PmkiTQ9Fv95L/KYuMQTvfOM2ODrcp6yPbJzk+LUX wFaoyXe06sS/jUfBiTqNRbdHvEuIInVNi9wWtsiDGEUyIDeOBnQPTP7n2pVUEqRZ9p oWoMQGktcuOPg== Message-ID: From: sashiko-bot@kernel.org Subject: Re: [PATCH v8 10/39] drm/fb-dma-helper: Handle framebuffers without a GEM object To: "Maxime Ripard" Cc: dri-devel@lists.freedesktop.org In-Reply-To: <20261106-drm-state-readout-v8-10-cbe78624e1bc@kernel.org> References: <20261106-drm-state-readout-v8-0-cbe78624e1bc@kernel.org> <20261106-drm-state-readout-v8-10-cbe78624e1bc@kernel.org> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Fri, 06 Nov 2026 13:32:09 +0000 X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: sashiko-reviews@lists.linux.dev Sender: "dri-devel" X-Spam-Status: No, score=-10.8 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=ham autolearn_force=no version=4.0.1 X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 X-Archived-By: Thank you for your contribution! Sashiko AI review found 1 potential issue to consider: - [Medium] drm/fb-dma-helper: drm_WARN_ON_ONCE() in drm_fb_dma_get_scanout_buffer() -- commit 42874beaaaa70520e8f9990fa06a12e91732fab6 Author: Maxime Ripard drm/fb-dma-helper: Handle framebuffers without a GEM object This commit updates drm_fb_dma_get_scanout_buffer() to return -ENODEV when a framebuffer has no backing GEM object on its first plane, such as a framebuffer reconstructed from hardware state readout. > diff --git a/drivers/gpu/drm/drm_fb_dma_helper.c b/drivers/gpu/drm/drm_fb= _dma_helper.c > index fd71969d2fb15..3a37253ab9f83 100644 > --- a/drivers/gpu/drm/drm_fb_dma_helper.c > +++ b/drivers/gpu/drm/drm_fb_dma_helper.c > @@ -179,6 +179,14 @@ int drm_fb_dma_get_scanout_buffer(struct drm_plane *= plane, > =20 > dma_obj =3D drm_fb_dma_get_gem_obj(fb, 0); > =20 > + /* > + * The framebuffer has no GEM object backing its first plane, > + * like a framebuffer reconstructed from a hardware state > + * readout: we cannot access its contents. > + */ > + if (!dma_obj) > + return -ENODEV; > + > /* Buffer should be accessible from the CPU */ > if (drm_gem_is_imported(&dma_obj->base)) > return -ENODEV; [Severity: Medium] Does calling drm_fb_dma_get_gem_obj(fb, 0) here trigger a drm_WARN_ON_ONCE() when fb->obj[0] is NULL? drm_fb_dma_get_gem_obj() calls drm_gem_fb_get_obj(), which warns when a plane has no backing GEM object: drivers/gpu/drm/drm_gem_framebuffer_helper.c:drm_gem_fb_get_obj() { ... if (drm_WARN_ON_ONCE(dev, plane >=3D ARRAY_SIZE(fb->obj))) return NULL; else if (drm_WARN_ON_ONCE(dev, !fb->obj[plane])) return NULL; ... } When a panic occurs while a hardware readout framebuffer is still active, drm_fb_dma_get_scanout_buffer() will hit that warning (or a nested panic if panic_on_warn is set). Note that the following patch in the series, commit "drm/gem-atomic-helper: Handle framebuffers without a GEM object", checks state->fb->obj[i] directly in drm_gem_plane_helper_prepare_fb() to avoid this same warning. Checking !fb->obj[0] before calling drm_fb_dma_get_gem_obj(fb, 0) would avoid it here as well. --=20 Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/20261106-drm-state-= readout-v8-0-cbe78624e1bc@kernel.org?part=3D10