From patchwork Mon Jan 9 23:15:55 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Marijn Suijten X-Patchwork-Id: 640731 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 458C6C678DC for ; Mon, 9 Jan 2023 23:17:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237882AbjAIXQu (ORCPT ); Mon, 9 Jan 2023 18:16:50 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46228 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237682AbjAIXQO (ORCPT ); Mon, 9 Jan 2023 18:16:14 -0500 Received: from relay06.th.seeweb.it (relay06.th.seeweb.it [5.144.164.167]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DEF0D2668 for ; Mon, 9 Jan 2023 15:16:10 -0800 (PST) Received: from localhost.localdomain (94-211-6-86.cable.dynamic.v4.ziggo.nl [94.211.6.86]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by m-r2.th.seeweb.it (Postfix) with ESMTPSA id 5D8883EB5B; Tue, 10 Jan 2023 00:16:07 +0100 (CET) From: Marijn Suijten To: phone-devel@vger.kernel.org Cc: ~postmarketos/upstreaming@lists.sr.ht, AngeloGioacchino Del Regno , Konrad Dybcio , Martin Botka , Jami Kettunen , Marijn Suijten , Rob Clark , Abhinav Kumar , Dmitry Baryshkov , Sean Paul , David Airlie , Daniel Vetter , Stephen Boyd , Vinod Koul , Drew Davenport , linux-arm-msm@vger.kernel.org, dri-devel@lists.freedesktop.org, freedreno@lists.freedesktop.org, linux-kernel@vger.kernel.org Subject: [PATCH v3] drm/msm/dpu: Disallow unallocated resources to be returned Date: Tue, 10 Jan 2023 00:15:55 +0100 Message-Id: <20230109231556.344977-1-marijn.suijten@somainline.org> X-Mailer: git-send-email 2.39.0 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-arm-msm@vger.kernel.org In the event that the topology requests resources that have not been created by the system (because they are typically not represented in dpu_mdss_cfg ^1), the resource(s) in global_state (in this case DSC blocks, until their allocation/assignment is being sanity-checked in "drm/msm/dpu: Reject topologies for which no DSC blocks are available") remain NULL but will still be returned out of dpu_rm_get_assigned_resources, where the caller expects to get an array containing num_blks valid pointers (but instead gets these NULLs). To prevent this from happening, where null-pointer dereferences typically result in a hard-to-debug platform lockup, num_blks shouldn't increase past NULL blocks and will print an error and break instead. After all, max_blks represents the static size of the maximum number of blocks whereas the actual amount varies per platform. ^1: which can happen after a git rebase ended up moving additions to _dpu_cfg to a different struct which has the same patch context. Fixes: bb00a452d6f7 ("drm/msm/dpu: Refactor resource manager") Signed-off-by: Marijn Suijten Reviewed-by: Dmitry Baryshkov --- Changes since v2: - Dropped all 7 other patches that were queued for -next; - Reworded error message to clarify that the requested resource should have already been allocated, rather than sounding like dpu_rm_get_assigned_resources is (re)allocating/(re)assigning resources here; - This patch is now (implicitly!) based after "drm/msm/dpu: Reject topologies for which no DSC blocks are available", which should make it impossible to reach this condition, making it more of a safeguard in case of future code changes and/or hidden issues: and is more clearly conveyed in the patch message as well. v2: https://lore.kernel.org/linux-arm-msm/20221221231943.1961117-5-marijn.suijten@somainline.org/ drivers/gpu/drm/msm/disp/dpu1/dpu_rm.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_rm.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_rm.c index 73b3442e7467..7ada957adbbb 100644 --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_rm.c +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_rm.c @@ -660,6 +660,11 @@ int dpu_rm_get_assigned_resources(struct dpu_rm *rm, blks_size, enc_id); break; } + if (!hw_blks[i]) { + DPU_ERROR("Allocated resource %d unavailable to assign to enc %d\n", + type, enc_id); + break; + } blks[num_blks++] = hw_blks[i]; }