From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7ED67358373; Thu, 30 Jul 2026 15:48:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785426514; cv=none; b=d2QwXD94Rxl4IfgVs68zIUWNyIh/22lWGlBCTRrv4GJru6KsUZAHJDnEA6xUvavtoheBm5ZMgsjjdRs2m9ov6U046uqhvSeq7/CNkJJn766N4mfMo1ylVSyjy2b9G6qZp6tfn/e8de5AFSdBu3p8EmacftuuOZ5LAX/kgQJ36sU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785426514; c=relaxed/simple; bh=/s2jjV+Rz/Vyv8ffdcxAwmEqWVoJ13yApUoLSPgKH18=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=qrnenii0kfEW3l/GjVRJMvDO2ocsyYmiUEFnI2nOIp/Sp6T5fmVxzllckADGGvu6BjNpDrvTsLnFiRa2Q2t04IF0PWShy/rfW4AwcgG8IYn7ufSDLlzm/azFGMptCpRmIN7YOjxQAFRiJm3DQYLwbAii25uhgqABBnp55hgJ5cg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=hY0OPMP7; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="hY0OPMP7" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E2F2C1F000E9; Thu, 30 Jul 2026 15:48:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1785426513; bh=NStuLYkYGbAIIAP7UgU64tCywn7p/aZV8E3+rJsLTmU=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=hY0OPMP7KNsiR4C6NaxQ45UNnnRt2IytpEf8B7JLlXNSxykJpaju9bax64BoE+NTy pFMgL2aR+j3DBhZP+isHhhhWIja44zhxOwPyzuCD+my0OH0tME3uMmcdPxvU1CG/wp vvzRY/Kvh/ox3YpOv3fkh27x0nnB4lLOixV73pUU= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Imre Deak , Lyude Paul , intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, Jonas Emilsson , Luca Coelho , Maarten Lankhorst Subject: [PATCH 6.12 446/602] drm/dp_mst: Handle torn-down topology gracefully in drm_dp_mst_topology_queue_probe() Date: Thu, 30 Jul 2026 16:13:58 +0200 Message-ID: <20260730141445.334798009@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260730141435.976815864@linuxfoundation.org> References: <20260730141435.976815864@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Luca Coelho commit 613059875958e7b217b250ed14c3b189f9488421 upstream. A hotplug or link-loss event can tear down the MST topology (setting mgr->mst_state = false and mgr->mst_primary = NULL) concurrently with a caller invoking drm_dp_mst_topology_queue_probe(). Since the check is already performed under mgr->lock, the condition is not a programming error but a valid race -- the topology was valid when the caller decided to call this function, but was torn down before the lock was acquired. Replace the drm_WARN_ON() with a graceful early return. This eliminates spurious kernel warnings and the resulting compositor crashes observed when connecting/disconnecting DP MST monitors, while keeping the correct behavior of doing nothing when MST is not active. A drm_dbg_mst() trace is added so the skipped probe remains observable under MST debug logging. The existing WARN_ON(mgr->mst_primary) in drm_dp_mst_topology_mgr_set_mst() already catches the case where the topology is initialized twice, so no diagnostic coverage is lost. Fixes: dbaeef363ea5 ("drm/dp_mst: Add a helper to queue a topology probe") Cc: Imre Deak Cc: Lyude Paul Cc: stable@vger.kernel.org Cc: intel-gfx@lists.freedesktop.org Cc: dri-devel@lists.freedesktop.org Signed-off-by: Jonas Emilsson Signed-off-by: Luca Coelho Link: https://lore.kernel.org/all/20260503034533.1023686-1-jonas.emilsson@gmail.com Acked-by: Imre Deak Link: https://patch.msgid.link/20260622140532.526722-1-luciano.coelho@intel.com Signed-off-by: Maarten Lankhorst Signed-off-by: Greg Kroah-Hartman --- drivers/gpu/drm/display/drm_dp_mst_topology.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) --- a/drivers/gpu/drm/display/drm_dp_mst_topology.c +++ b/drivers/gpu/drm/display/drm_dp_mst_topology.c @@ -3743,8 +3743,10 @@ void drm_dp_mst_topology_queue_probe(str { mutex_lock(&mgr->lock); - if (drm_WARN_ON(mgr->dev, !mgr->mst_state || !mgr->mst_primary)) + if (!mgr->mst_state || !mgr->mst_primary) { + drm_dbg_kms(mgr->dev, "queue_probe skipped: topology torn down\n"); goto out_unlock; + } drm_dp_mst_topology_mgr_invalidate_mstb(mgr->mst_primary); drm_dp_mst_queue_probe_work(mgr);