From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from relay15.mail.gandi.net (relay15.mail.gandi.net [217.70.178.235]) (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 3B69B1C3BE0 for ; Fri, 1 Aug 2025 17:05:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.70.178.235 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754067940; cv=none; b=QOjHRiBEWZZQnLq5hTU/iwdVirOjy6Q0MOdyDiu59xG/ZQEnQYDSQ0CUfWUr7SNNdiSj8cicJ3MwJdJbg7RF0K4o2g+r+cAAFriDL7vGKKPyfrp3I0sxvzQzbfQFiPWqfPqkLG492UspMdv4/V8GuTUs7iuFQvLdxJXBCyQEDFA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754067940; c=relaxed/simple; bh=77LGnkqRlcQzJx7xZ4uWapnv8ICF3iNyaEBAchhFd5I=; h=From:Subject:Date:Message-Id:MIME-Version:Content-Type:To:Cc; b=gLrRRKypencVyKyOmP9AY7UIVaRc8qATSptfB8474qZKqnZv4JVRM3tjeIsKqUnlJMZaNkoBQt2S8qPXNTNzwSHyXoufG772lwziQYnKd3F59NX27LhdR3kNSP2LziGpmtJSOb1mYK5zV476OQUbLyvnholPWkCnEhVQ2bWH0AY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=bootlin.com; spf=pass smtp.mailfrom=bootlin.com; dkim=pass (2048-bit key) header.d=bootlin.com header.i=@bootlin.com header.b=dYo82Kz2; arc=none smtp.client-ip=217.70.178.235 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=bootlin.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=bootlin.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=bootlin.com header.i=@bootlin.com header.b="dYo82Kz2" Received: by mail.gandi.net (Postfix) with ESMTPSA id 95A064422B; Fri, 1 Aug 2025 17:05:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=gm1; t=1754067935; 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=aD/nGiCc+YDCCx8g28qn2jStr5eOipu4kAA3wazt60A=; b=dYo82Kz2g0XG37+HAIyUSe1wvU/3lqmUzqgOGOc9XPTUIlYZXzUXtV/IuhOsd6EoE5LdpW /KHotDEkI8Pixvc/6UCyqmqxp/jL9YfbkF7MacTeVxn8Lx984eyNJzCXn8MY5aQuZgUCLr dcjRsyaPqhVTBVy1PWbv61YJek8DpIa3MKriReGpRzPsedNf0KxQv8EvvcRab9cWnNcVOF JX+3ShYH+RdKUOFnrv/zqTKRvK8DvPWfkFRURGyc53X5OaCrkzauS5PYHw0nuLEFoPoP5t mYwc4VfRJZ7APdUF+Z3nEThkc7a61kyrWgSkuJ6xgANLoQ44Lvgn5C3IHJNNyA== From: Luca Ceresoli Subject: [PATCH v2 0/9] drm/bridge: get/put the bridge returned by drm_bridge_get_next_bridge() Date: Fri, 01 Aug 2025 19:05:22 +0200 Message-Id: <20250801-drm-bridge-alloc-getput-drm_bridge_get_next_bridge-v2-0-888912b0be13@bootlin.com> 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="utf-8" Content-Transfer-Encoding: 8bit X-B4-Tracking: v=1; b=H4sIANLzjGgC/6WOTQ6DIBhEr2JYlwawpcVV79EYg/zolygYoMbGe Pei7Q26fG+SmVlRNAFMRFWxomBmiOBdBnYqkOql6wwGnRkxwq7kRgTWYcRtAJ0TOQxe4c6k6ZV 233x9k03jzJJ+jKm2XErLGS05ysVTMBaWY/RZZ+4hJh/ex4eZ7vavuZligi93wUgrlC25eLTep wHcWfkR1du2fQA+e3GR9gAAAA== X-Change-ID: 20250709-drm-bridge-alloc-getput-drm_bridge_get_next_bridge-1df6aaf62136 To: Andrzej Hajda , Neil Armstrong , Robert Foss , Laurent Pinchart , Jonas Karlman , Jernej Skrabec , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , Liu Ying , Shawn Guo , Sascha Hauer , Pengutronix Kernel Team , Fabio Estevam , Tomi Valkeinen , Philipp Zabel Cc: Hui Pu , Thomas Petazzoni , linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, imx@lists.linux.dev, linux-arm-kernel@lists.infradead.org, Luca Ceresoli , Andy Shevchenko , Andrew Morton , Zijun Hu , Greg Kroah-Hartman X-Mailer: b4 0.14.2 X-GND-State: clean X-GND-Score: -100 X-GND-Cause: gggruggvucftvghtrhhoucdtuddrgeeffedrtdefgddutdegvdegucetufdoteggodetrfdotffvucfrrhhofhhilhgvmecuifetpfffkfdpucggtfgfnhhsuhgsshgtrhhisggvnecuuegrihhlohhuthemuceftddunecusecvtfgvtghiphhivghnthhsucdlqddutddtmdenucfjughrpefhufffkfggtgfgvfevofesthekredtredtjeenucfhrhhomhepnfhutggrucevvghrvghsohhlihcuoehluhgtrgdrtggvrhgvshholhhisegsohhothhlihhnrdgtohhmqeenucggtffrrghtthgvrhhnpeejjefhgfffleevhefhfeduhedtfedttedtkefgkeeuieehtdeifeduveejffevgeenucffohhmrghinhepfhhrvggvuggvshhkthhophdrohhrghdpkhgvrhhnvghlrdhorhhgnecukfhppedvrgdtvdemieejtdemvddtvddtmegvrgdtudemsggvgedumeelhegvjeemfeegfeemledufegvnecuvehluhhsthgvrhfuihiivgeptdenucfrrghrrghmpehinhgvthepvdgrtddvmeeijedtmedvtddvtdemvggrtddumegsvgegudemleehvgejmeefgeefmeeludefvgdphhgvlhhopegludelvddrudeikedrudejkedruddukegnpdhmrghilhhfrhhomheplhhutggrrdgtvghrvghsohhlihessghoohhtlhhinhdrtghomhdpnhgspghrtghpthhtohepvdelpdhrtghpthhtohepmhgrrghrthgvnhdrlhgrnhhkhhhorhhstheslhhinhhugidrihhnthgvlhdrtghomhdprhgtphhtthhopehprdiirggsvghlsehpvghng hhuthhrohhnihigrdguvgdprhgtphhtthhopehshhgrfihnghhuoheskhgvrhhnvghlrdhorhhgpdhrtghpthhtohepjfhuihdrrfhusehgvghhvggrlhhthhgtrghrvgdrtghomhdprhgtphhtthhopegurhhiqdguvghvvghlsehlihhsthhsrdhfrhgvvgguvghskhhtohhprdhorhhgpdhrtghpthhtoheprghnughriigvjhdrhhgrjhgurgesihhnthgvlhdrtghomhdprhgtphhtthhopehrfhhoshhssehkvghrnhgvlhdrohhrghdprhgtphhtthhopehthhhomhgrshdrphgvthgriiiiohhnihessghoohhtlhhinhdrtghomh Note: the cover in v1 was mentioning by mistake drm_bridge_get_last_bridge() instead of drm_bridge_get_next_bridge(). ^^^^ This series adds drm_bridge_get/put() calls for DRM bridges returned by drm_bridge_get_next_bridge(). 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) There are various users of drm_bridge_get_next_bridge() which cannot be converted easily. Luckily they are not really looking for the next bridge, but for something else, such as getting the last bridge in the encoder chain or checking whether a bridge is the last in the encoder chain. So introduce better functions for those users and use them instead of drm_bridge_get_next_bridge(), making the code cleaner at the same time. Finally add a drm_bridge_get() to drm_bridge_get_next_bridge() and drm_bridge_put() to the remaining, and legitimate, calls. [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: - Use cleanup action in patches 4, 8 and 9 - Fix: replace get_last -> get_next in cover - Link to v1: https://lore.kernel.org/r/20250709-drm-bridge-alloc-getput-drm_bridge_get_next_bridge-v1-0-48920b9cf369@bootlin.com --- Luca Ceresoli (9): list: add list_last_entry_or_null() drm/bridge: add drm_bridge_chain_get_last_bridge() drm/bridge: imx93-mipi-dsi: use drm_bridge_chain_get_last_bridge() drm/omapdrm: use drm_bridge_chain_get_last_bridge() drm/bridge: add drm_bridge_is_last() drm/display: bridge_connector: use drm_bridge_is_last() drm/bridge: get the bridge returned by drm_bridge_get_next_bridge() drm/bridge: put the bridge returned by drm_bridge_get_next_bridge() drm/imx: parallel-display: put the bridge returned by drm_bridge_get_next_bridge() drivers/gpu/drm/bridge/imx/imx93-mipi-dsi.c | 12 ++++------ drivers/gpu/drm/display/drm_bridge_connector.c | 5 ++-- drivers/gpu/drm/drm_bridge.c | 3 +-- drivers/gpu/drm/imx/ipuv3/parallel-display.c | 4 ++-- drivers/gpu/drm/omapdrm/omap_drv.c | 6 ++--- include/drm/drm_bridge.h | 32 +++++++++++++++++++++++++- include/linux/list.h | 14 +++++++++++ 7 files changed, 57 insertions(+), 19 deletions(-) --- base-commit: b13c47e0f6f5a7be56ed93d596f80eb9d8e12c77 change-id: 20250709-drm-bridge-alloc-getput-drm_bridge_get_next_bridge-1df6aaf62136 Best regards, -- Luca Ceresoli