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 31F333C3F4C; Thu, 30 Jul 2026 14:53:42 +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=1785423223; cv=none; b=aK+FGEsy23ALOITUS2LVNUmDGt/9Yn9Uk9eDI/enxN6RD0oaKQgZQcrqISnQeoNU8VlRWHrYOm44NW/0qfb1YyziDdXBCWAEytsSjkLQ+cU/cDTpeUSjP+E2fHWTWP0q5VuEi8p+/p9k9jRVALl5NbCFJmRLT6ucH3VlhrmcvHs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785423223; c=relaxed/simple; bh=KGWlvSzi4gygoksALEjWXJ1ZXQDcc3TpAdsLT4mkpEQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=XS091TsQrB0HGuQ28dwbfUifE7ck3ADksPQnIH/t2zBvOpwdxUrrtPdCnTYahnbVyZ1k997s5aiqbGi003hmtWA6w9Lw8XAd323pIW40CfT0j72G+rVKD1yWwovYq1hUlsdG0PMkNJ1WJMNksw0YTeSz3olGCL0mM0XkW+nJjmk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=T9bvCTJb; 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="T9bvCTJb" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 965CB1F000E9; Thu, 30 Jul 2026 14:53:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1785423222; bh=2mM3eqLxKuc25YYALIM4LgVx2G3SlG8xlQEfvTfCj04=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=T9bvCTJbN2vuPVEZC3UOWEavjfX4x66jWh9p145Rd2TtPQu8Vw9+t+mdvyOwsv8Hz KMO8y5gcAwkZnQgr64cdUCJQd73W16ZWXxqvyqN6LiOYUq0+ZSedMOYSCd61y4yYFK +aJMxwSlrANOe1gst+QThFQmtgqqstq2dW0Otuqk= 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 7.1 710/744] drm/dp_mst: Handle torn-down topology gracefully in drm_dp_mst_topology_queue_probe() Date: Thu, 30 Jul 2026 16:16:23 +0200 Message-ID: <20260730141459.368002107@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260730141444.267951807@linuxfoundation.org> References: <20260730141444.267951807@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 7.1-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 @@ -3740,8 +3740,10 @@ 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);