From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from pidgin.makrotopia.org (pidgin.makrotopia.org [185.142.180.65]) (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 506D438837C for ; Sat, 25 Jul 2026 02:58:13 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=185.142.180.65 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784948294; cv=none; b=g52m8GtKSxNoGIGKGn+2ls5vfmlKuAhedfD8/GHf3uchK96+m7kSklykj78bpIz06yqvlT8OujG/L5vpsxN0cRhdfMBkI5ZcKeMuxEnfIhJfLzrmWah7eOrpPY8ZzwYymp9VL109tuR9fCGqoL2QIRWKscEnXSFc0G0PT2OBAY8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784948294; c=relaxed/simple; bh=jrTgka+ct8+dK3aVK/RgKLDCanFYhnlIsVkTvRq12aU=; h=Date:From:To:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=mzoDrVk8ASxfZPJuQ0jkzFKsa4zaq9R0eVfavnBN6l6DZqwtzt5SSa9hMUuuhVQlbSjekkrvhQrGnrHFyelX4CNdeal2nVSe29fzGrXj/m7GKJsE1fGxf5vYfHuazJKWFOaovtpxApipK964DdApnFsYVL12nwLLjaCIVccb3Ow= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=makrotopia.org; spf=pass smtp.mailfrom=makrotopia.org; arc=none smtp.client-ip=185.142.180.65 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=makrotopia.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=makrotopia.org Received: from local by pidgin.makrotopia.org with esmtpsa (TLS1.3:TLS_AES_256_GCM_SHA384:256) (Exim 4.99) (envelope-from ) id 1wnSaT-000000002xV-2XOj; Sat, 25 Jul 2026 02:58:05 +0000 Date: Sat, 25 Jul 2026 03:58:02 +0100 From: Daniel Golle To: Andrzej Hajda , Neil Armstrong , Robert Foss , Laurent Pinchart , Jonas Karlman , Jernej Skrabec , Luca Ceresoli , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , Matthias Brugger , AngeloGioacchino Del Regno , Allen Chen , Hermes Wu , Pin-yen Lin , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org, Chen-Yu Tsai Subject: [PATCH v6 01/13] drm/bridge: it6505: quiesce event sources and work on remove() Message-ID: <248a9b6a19da93d75b59e9fcad0e03fe94ea67d8.1784947240.git.daniel@makrotopia.org> References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: struct it6505 is freed by devres right after remove() returns, but remove() cancels none of the driver's work items, so link_works, hdcp_wait_ksv_list, hdcp_work and extcon_wq can still run afterwards and dereference freed memory. Cancelling alone would not be enough: the threaded IRQ and the extcon notifier stay live until devres teardown and can requeue the works. Unregister the extcon notifier and disable the IRQ first, then cancel all work. Make it6505_remove_notifier_module() idempotent, tracking the registration in a flag under extcon_lock, as both .detach() and remove() call it now. The notifier_call pointer is left intact: extcon traverses its raw notifier chain without holding a lock, so a traversal racing with the unregistration may still invoke the callback. Also initialise extcon_wq in probe: cancel_work_sync() on a never-initialised work item trips WARN_ON(!work->func). Fixes: b5c84a9edcd4 ("drm/bridge: add it6505 driver") Signed-off-by: Daniel Golle --- v6: track registration in a flag instead of clearing notifier_call, which an unlocked chain traversal racing the unregistration could have called as NULL v5: serialise notifier registration state with extcon_lock v4: * quiesce event sources before cancelling work; retitled * initialise extcon_wq in probe to avoid WARN_ON(!work->func) v3: new patch drivers/gpu/drm/bridge/ite-it6505.c | 27 +++++++++++++++++++++------ 1 file changed, 21 insertions(+), 6 deletions(-) diff --git a/drivers/gpu/drm/bridge/ite-it6505.c b/drivers/gpu/drm/bridge/ite-it6505.c index 8ecb43611dba..a7ba6a0befda 100644 --- a/drivers/gpu/drm/bridge/ite-it6505.c +++ b/drivers/gpu/drm/bridge/ite-it6505.c @@ -443,6 +443,7 @@ struct it6505 { struct drm_display_mode source_output_mode; struct drm_display_mode video_info; struct notifier_block event_nb; + bool extcon_registered; struct extcon_dev *extcon; struct work_struct extcon_wq; int extcon_state; @@ -2934,11 +2935,15 @@ static int it6505_use_notifier_module(struct it6505 *it6505) int ret; struct device *dev = it6505->dev; + mutex_lock(&it6505->extcon_lock); it6505->event_nb.notifier_call = it6505_extcon_notifier; - INIT_WORK(&it6505->extcon_wq, it6505_extcon_work); ret = devm_extcon_register_notifier(it6505->dev, it6505->extcon, EXTCON_DISP_DP, &it6505->event_nb); + if (!ret) + it6505->extcon_registered = true; + mutex_unlock(&it6505->extcon_lock); + if (ret) { dev_err(dev, "failed to register notifier for DP"); return ret; @@ -2951,13 +2956,16 @@ static int it6505_use_notifier_module(struct it6505 *it6505) static void it6505_remove_notifier_module(struct it6505 *it6505) { - if (it6505->extcon) { - devm_extcon_unregister_notifier(it6505->dev, - it6505->extcon, EXTCON_DISP_DP, + mutex_lock(&it6505->extcon_lock); + if (it6505->extcon && it6505->extcon_registered) { + devm_extcon_unregister_notifier(it6505->dev, it6505->extcon, + EXTCON_DISP_DP, &it6505->event_nb); - - flush_work(&it6505->extcon_wq); + it6505->extcon_registered = false; } + mutex_unlock(&it6505->extcon_lock); + + flush_work(&it6505->extcon_wq); } static void __maybe_unused it6505_delayed_audio(struct work_struct *work) @@ -3615,6 +3623,7 @@ static int it6505_i2c_probe(struct i2c_client *client) INIT_WORK(&it6505->link_works, it6505_link_training_work); INIT_WORK(&it6505->hdcp_wait_ksv_list, it6505_hdcp_wait_ksv_list); INIT_DELAYED_WORK(&it6505->hdcp_work, it6505_hdcp_work); + INIT_WORK(&it6505->extcon_wq, it6505_extcon_work); init_completion(&it6505->extcon_completion); memset(it6505->dpcd, 0, sizeof(it6505->dpcd)); it6505->powered = false; @@ -3647,6 +3656,12 @@ static void it6505_i2c_remove(struct i2c_client *client) drm_bridge_remove(&it6505->bridge); drm_dp_aux_unregister(&it6505->aux); it6505_debugfs_remove(it6505); + it6505_remove_notifier_module(it6505); + disable_irq(it6505->irq); + cancel_work_sync(&it6505->link_works); + cancel_work_sync(&it6505->hdcp_wait_ksv_list); + cancel_delayed_work_sync(&it6505->hdcp_work); + cancel_work_sync(&it6505->extcon_wq); it6505_poweroff(it6505); it6505_remove_edid(it6505); } -- 2.55.0