From mboxrd@z Thu Jan 1 00:00:00 1970 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 gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id BD030C87FD2 for ; Fri, 8 Aug 2025 14:49:33 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 3435310E957; Fri, 8 Aug 2025 14:49:33 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=bootlin.com header.i=@bootlin.com header.b="e07+lHfe"; dkim-atps=neutral Received: from relay7-d.mail.gandi.net (relay7-d.mail.gandi.net [217.70.183.200]) by gabe.freedesktop.org (Postfix) with ESMTPS id 2DCE910E06A for ; Fri, 8 Aug 2025 14:49:30 +0000 (UTC) Received: by mail.gandi.net (Postfix) with ESMTPSA id 2E8AE4397C; Fri, 8 Aug 2025 14:49:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=gm1; t=1754664569; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=YuF4nnvi3fV43zgWxp+tW6JoStyuwuQCwhjAMoEMygw=; b=e07+lHfe25z6EU4RbT2WyUVdiZane0nD01Q4wJLAx9JlqBRpSAKJEW2itqfpya2L9bRCts hhhzK8bjqR/KHEkPfw2zaJz074hSaWMdP6A4xzg+4MjQfL4jAh9pZl7HUQ0iHLg2wc6OVm mDSmY45HdYThz8gIs0SV4M/bkRgKWPOwZRdgTuqw9IMFiqp/Ow5dsUou147Us6vtUdIL4G dQ2UtLveUwKvUgJ9GQdj4ap3rY4ql0boysIbh9zUVlSnjfhADJ1OCJWpuiT0WhocONNs60 0Dk0mr4HFHzEH5rdrk1ZmudGfUlqfr6slyMcIBeiac4EigxFUIgHsPQ9ORYHcQ== From: Luca Ceresoli Subject: [PATCH v2 0/9] drm/bridge: get/put the bridge when looping over the encoder chain Date: Fri, 08 Aug 2025 16:49:07 +0200 Message-Id: <20250808-drm-bridge-alloc-getput-for_each_bridge-v2-0-edb6ee81edf1@bootlin.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit X-B4-Tracking: v=1; b=H4sIAGMOlmgC/42P7Y6DIBBFX8Xwe2kAFT/SbPoeTdMMOFRSlS5Q0 6bx3Rd1H2B/3pnknnM/JKC3GEibfYjH2QbrphTEV0Z0D9MNqe1SJoKJklW8pp0fqfK2Sx8YBqf pDePjGalx/oqg++vf0/CCA/JKyRJIant4NPa1kc6XPXv8eSZg3I9EQUCq3Tja2GadUEVthMqZE WXTVLCWQcc0GtCy1qI0tc5ztlaPGAJspm123ESlYIxzyeWBJ2VO7+gnHE5g/f1tD4nxTVaH3ob o/HsbP/NNYt8p8n/vnDllVGFtCkDGJDYn5Vwc7LRiyGVZll80rISvZAEAAA== X-Change-ID: 20250718-drm-bridge-alloc-getput-for_each_bridge-f141ae17b65a To: Andrzej Hajda , Neil Armstrong , Robert Foss , Laurent Pinchart , Jonas Karlman , Jernej Skrabec , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , Miguel Ojeda , Nathan Chancellor , Nick Desaulniers , Bill Wendling , Justin Stitt , Tomi Valkeinen Cc: Dmitry Baryshkov , Chaoyi Chen , Hui Pu , Thomas Petazzoni , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, llvm@lists.linux.dev, Luca Ceresoli X-Mailer: b4 0.14.2 X-GND-State: clean X-GND-Score: -100 X-GND-Cause: gggruggvucftvghtrhhoucdtuddrgeeffedrtdefgdduvdegtdelucetufdoteggodetrfdotffvucfrrhhofhhilhgvmecuifetpfffkfdpucggtfgfnhhsuhgsshgtrhhisggvnecuuegrihhlohhuthemuceftddunecusecvtfgvtghiphhivghnthhsucdlqddutddtmdenucfjughrpefhufffkfggtgfgvfevofesthekredtredtjeenucfhrhhomhepnfhutggrucevvghrvghsohhlihcuoehluhgtrgdrtggvrhgvshholhhisegsohhothhlihhnrdgtohhmqeenucggtffrrghtthgvrhhnpeejjefhgfffleevhefhfeduhedtfedttedtkefgkeeuieehtdeifeduveejffevgeenucffohhmrghinhepfhhrvggvuggvshhkthhophdrohhrghdpkhgvrhhnvghlrdhorhhgnecukfhppeejkedrvdduvddrvdejrdduudehnecuvehluhhsthgvrhfuihiivgeptdenucfrrghrrghmpehinhgvthepjeekrddvuddvrddvjedrudduhedphhgvlhhopegludejvddrudeirddtrddungdpmhgrihhlfhhrohhmpehluhgtrgdrtggvrhgvshholhhisegsohhothhlihhnrdgtohhmpdhnsggprhgtphhtthhopedvhedprhgtphhtthhopehnihgtkhdruggvshgruhhlnhhivghrshdolhhkmhhlsehgmhgrihhlrdgtohhmpdhrtghpthhtohepmhhorhgsohesghhoohhglhgvrdgtohhmpdhrtghpthhtohepshhimhhonhgrsehffhiflhhlrdgthhdprhgtphhtthhopefnrghurhgvnhhtrdhpihhntghhrghrthesihguv ggrshhonhgsohgrrhgurdgtohhmpdhrtghpthhtohepthhomhhirdhvrghlkhgvihhnvghnsehiuggvrghsohhnsghorghrugdrtghomhdprhgtphhtthhopehjohhnrghssehkfihisghoohdrshgvpdhrtghpthhtoheprhhfohhssheskhgvrhhnvghlrdhorhhgpdhrtghpthhtohepohhjvggurgeskhgvrhhnvghlrdhorhhg X-GND-Sasl: luca.ceresoli@bootlin.com X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" This series adds drm_bridge_get/put() calls for DRM bridges used when looping over bridges in an encoder chain. This is part of the work towards removal of bridges from a still existing DRM pipeline without use-after-free. The grand plan was discussed in [1]. Here's the work breakdown (➜ marks the current series): 1. ➜ add refcounting to DRM bridges (struct drm_bridge) (based on devm_drm_bridge_alloc() [0]) A. ✔ add new alloc API and refcounting (in v6.16-rc1) B. ✔ convert all bridge drivers to new API (now in drm-misc-next) C. ✔ kunit tests (now in drm-misc-next) D. ✔ add get/put to drm_bridge_add/remove() + attach/detach() and warn on old allocation pattern (now in drm-misc-next) E. ➜ add get/put on drm_bridge accessors 1. ✔ drm_bridge_chain_get_first_bridge() + add a cleanup action 2. … drm_bridge_get_prev_bridge() 3. … drm_bridge_get_next_bridge() 4. ➜ drm_for_each_bridge_in_chain() 5. drm_bridge_connector_init 6. of_drm_find_bridge 7. drm_of_find_panel_or_bridge, *_of_get_bridge F. debugfs improvements 2. handle gracefully atomic updates during bridge removal 3. … avoid DSI host drivers to have dangling pointers to DSI devices 4. finish the hotplug bridge work, removing the "always-disconnected" connector, moving code to the core and potentially removing the hotplug-bridge itself (this needs to be clarified as points 1-3 are developed) Most loops on the encoder bridge chain are based on drm_for_each_bridge_in_chain(), which does not get/put the bridge pointed to by the loop iterator. Add a scoped variant that ensures ta reference to the bridge pointed to by the iterator is taken/released before/after every iteration (and when breaking out of the loop). Using the scoped version, the bridge being iterated on will always have a reference taken during the shole iteration. This is similar to what for_each_child_of_node() and similar for_each_* macros do. All conversions are trivial except for drm_bridge_connector_init() which needs some preliminary cleanups (patches 1-2). omapdrm/omap_encoder.c is the only driver iterating over the encoder bridge chain starting from a specific bridge, instead of iterating over the whole list. For this use case, add a drm_for_each_bridge_in_chain_from() variant. This series depends on: * commit 103578241512 ("drm/bridge-connector: Fix bridge in drm_connector_hdmi_audio_init()"), currently in drm-misc-fixes, not yet on drm-misc-next [0] https://gitlab.freedesktop.org/drm/misc/kernel/-/commit/0cc6aadd7fc1e629b715ea3d1ba537ef2da95eec [1] https://lore.kernel.org/lkml/20250206-hotplug-drm-bridge-v6-0-9d6f2c9c3058@bootlin.com/t/#u Signed-off-by: Luca Ceresoli --- Changes in v2: - Prune series dependency list - Clarify wording in cover letter and patch 3 - Link to v1: https://lore.kernel.org/r/20250723-drm-bridge-alloc-getput-for_each_bridge-v1-0-be8f4ae006e9@bootlin.com --- Luca Ceresoli (9): drm/display: bridge-connector: use scope-specific variable for the bridge pointer drm/display: bridge-connector: remove unused variable assignment drm/bridge: add drm_for_each_bridge_in_chain_scoped() drm/display: bridge-connector: use drm_for_each_bridge_in_chain_scoped() drm/atomic: use drm_for_each_bridge_in_chain_scoped() drm/bridge: use drm_for_each_bridge_in_chain_scoped() drm/bridge: remove drm_for_each_bridge_in_chain() drm/bridge: add drm_for_each_bridge_in_chain_from() drm/omap: use drm_for_each_bridge_in_chain_from() .clang-format | 2 +- drivers/gpu/drm/display/drm_bridge_connector.c | 13 +++---- drivers/gpu/drm/drm_atomic.c | 3 +- drivers/gpu/drm/drm_bridge.c | 3 +- drivers/gpu/drm/omapdrm/omap_encoder.c | 4 +- include/drm/drm_bridge.h | 52 ++++++++++++++++++++++++-- 6 files changed, 58 insertions(+), 19 deletions(-) --- base-commit: d2b48f2b30f25997a1ae1ad0cefac68c25f8c330 change-id: 20250718-drm-bridge-alloc-getput-for_each_bridge-f141ae17b65a prerequisite-message-id: <20250620011616.118-1-kernel@airkyi.com> prerequisite-patch-id: ba5a6a15ea02bcee387db0e92ffb4cd0e1fbf816 Best regards, -- Luca Ceresoli