From patchwork Thu Mar 20 15:42:09 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Luca Ceresoli X-Patchwork-Id: 14024083 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 7388BC28B30 for ; Thu, 20 Mar 2025 15:42:43 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 8015D10E659; Thu, 20 Mar 2025 15:42:41 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=bootlin.com header.i=@bootlin.com header.b="m18W9V4w"; dkim-atps=neutral Received: from relay8-d.mail.gandi.net (relay8-d.mail.gandi.net [217.70.183.201]) by gabe.freedesktop.org (Postfix) with ESMTPS id 6B9F210E652 for ; Thu, 20 Mar 2025 15:42:35 +0000 (UTC) Received: by mail.gandi.net (Postfix) with ESMTPSA id ACB0D44408; Thu, 20 Mar 2025 15:42:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=gm1; t=1742485352; 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=8mBeHfjSG+AR7A8Fp8QKLSrhvK7lhd1SXAkNAnYVLtw=; b=m18W9V4w7yusNw0mo6qqU9toSKUuwPKXTEBs5rlqYEFiw4yzWXhSy1EChVjxOqiubNVJjD pAL2KTjUrvqX1tzM1/cEkI6ZOaVEzFJ8nBLpbpADeIq/6/Ayqk9wKswVouV6NfHHNExWw5 qayfzfiglank6Q4uNeCYNi5MXslQnDXWuQwiX8kro0kwzD5xfvJiD3cAGAxZYzlZm0yrdf bpSLDnc2PkZg3S7s0PDz49uSDOtQWVhv1CP5JVL4RRDpf1Y7DKDC7Uipt3XcQ5jCAXwtJw SKvFr4HyEtnAily0Fp+lKUbE8CL0CNj3JiMEAoILcnAW1QOGAn0KrBOE9AgrmQ== From: Luca Ceresoli Subject: [PATCH v8 0/5] drm/bridge: add devm_drm_bridge_alloc() with bridge refcount Date: Thu, 20 Mar 2025 16:42:09 +0100 Message-Id: <20250320-drm-bridge-refcount-v8-0-b3ddaa9f1368@bootlin.com> MIME-Version: 1.0 X-B4-Tracking: v=1; b=H4sIAFE33GcC/32NTQ7CIBCFr9LMWgzUUqgr72G6sPzYSSwYqETTc HfHHsDkbb75Mu9tkF1Cl+HcbJBcwYwxEOhDA2a+hbtjaImh5a3kJ9ExmxY2JbRkkvMmvsLKpLY DWYrvgT6fZPC9t15H4hnzGtNnHynqd/3fVxTjTMhWKuG16YfuMsW4PjAcTVxgrLV+AR1PxK24A AAA X-Change-ID: 20250314-drm-bridge-refcount-58d9503503f6 To: Andrzej Hajda , Neil Armstrong , Robert Foss , Laurent Pinchart , Jonas Karlman , Jernej Skrabec , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , Marek Vasut , Stefan Agner , Shawn Guo , Sascha Hauer , Pengutronix Kernel Team , Fabio Estevam , Inki Dae , Jagan Teki , Marek Szyprowski Cc: Thomas Petazzoni , Anusha Srivatsa , Paul Kocialkowski , Dmitry Baryshkov , =?utf-8?q?Herv=C3=A9_Codina?= , Hui Pu , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, imx@lists.linux.dev, linux-arm-kernel@lists.infradead.org, Luca Ceresoli X-Mailer: b4 0.14.2 X-GND-State: clean X-GND-Score: -100 X-GND-Cause: gggruggvucftvghtrhhoucdtuddrgeefvddrtddtgddugeekiedtucetufdoteggodetrfdotffvucfrrhhofhhilhgvmecuifetpfffkfdpucggtfgfnhhsuhgsshgtrhhisggvnecuuegrihhlohhuthemuceftddunecusecvtfgvtghiphhivghnthhsucdlqddutddtmdenucfjughrpefhufffkfggtgfgvfevofesthejredtredtjeenucfhrhhomhepnfhutggrucevvghrvghsohhlihcuoehluhgtrgdrtggvrhgvshholhhisegsohhothhlihhnrdgtohhmqeenucggtffrrghtthgvrhhnpefgieetkeekgfdtudevueffueffveekheeiudfhfedvhfeukeeuhffhtddtvdekfeenucffohhmrghinhepkhgvrhhnvghlrdhorhhgnecukfhppedvrgdtvdemieejtdemvddtvddtmegvrgdtudemsggvgedumeelhegvjeemfeegfeemledufegvnecuvehluhhsthgvrhfuihiivgeptdenucfrrghrrghmpehinhgvthepvdgrtddvmeeijedtmedvtddvtdemvggrtddumegsvgegudemleehvgejmeefgeefmeeludefvgdphhgvlhhopegludelvddrudeikedrudejkedruddukegnpdhmrghilhhfrhhomheplhhutggrrdgtvghrvghsohhlihessghoohhtlhhinhdrtghomhdpnhgspghrtghpthhtohepfedupdhrtghpthhtoheprhhfohhssheskhgvrhhnvghlrdhorhhgpdhrtghpthhtoheprghnughriigvjhdrhhgrjhgurgesihhnthgvlhdrtghomhdprhgtphhtthhopehtiihimhhmvghrmhgrnhhnsehsu hhsvgdruggvpdhrtghpthhtohepihhmgieslhhishhtshdrlhhinhhugidruggvvhdprhgtphhtthhopehjvghrnhgvjhdrshhkrhgrsggvtgesghhmrghilhdrtghomhdprhgtphhtthhopehluhgtrgdrtggvrhgvshholhhisegsohhothhlihhnrdgtohhmpdhrtghpthhtohepnfgruhhrvghnthdrphhinhgthhgrrhhtsehiuggvrghsohhnsghorghrugdrtghomhdprhgtphhtthhopehhvghrvhgvrdgtohguihhnrgessghoohhtlhhinhdrtghomh 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 improves the way DRM bridges are allocated and initialized and makes them reference-counted. The goal of reference counting is to avoid use-after-free by drivers which got a pointer to a bridge and keep it stored and used even after the bridge has been deallocated. The overall goal is supporting Linux devices with a DRM pipeline whose final components can be hot-plugged and hot-unplugged, including one or more bridges. For more details see the big picture [0]. DRM bridge drivers will have to be adapted to the new API -- the change is trivial for most cases. This series converts two of them to serve as an example. The remaining ones will be done as a follow-up after this first part is merged. After that, refcounting will have to be added on the two sides: all functions returning a bridge pointer and all code obtaining such a pointer. A few examples have been sent in v7 (link below), they are OK, but I removed them from v8 because they must be merged only after converting all bridges. Here's the grand plan: A. add new alloc API and refcounting (this series, at least patches 1-3) B. after (A), convert all bridge drivers to new API C. after (A), add documentation and kunit tests D. after (B), add get/put to drm_bridge_add/remove() + attach/detech() (patches 3-4 in the v7 series) E. after (B), convert accessors (including patches 5-9 in the v7 series which convert drm_bridge_chain_get_first_bridge() and its users); this is a large work and can be done in chunks Series layout: 1. Add the new API and refcounting: drm/bridge: add devm_drm_bridge_alloc() drm/bridge: add support for refcounting drm/bridge: deprecate old-style bridge allocation 2. convert a few bridge drivers (bridge providers) to the new API: drm/bridge: ti-sn65dsi83: use dynamic lifetime management drm/bridge: samsung-dsim: use dynamic lifetime management [0] https://lore.kernel.org/dri-devel/20250206-hotplug-drm-bridge-v6-0-9d6f2c9c3058@bootlin.com/ Signed-off-by: Luca Ceresoli --- Changes in v8: - Applied requested changes to patch 2 - Add R-by to other patches - Removed v7 patches 3-9: they are OK but must wait until all bridge drivers are converted to the new API - Added patch to deprecate old-style bridge allocation - Link to v7: https://lore.kernel.org/r/20250314-drm-bridge-refcount-v7-0-152571f8c694@bootlin.com --- Luca Ceresoli (5): drm/bridge: add devm_drm_bridge_alloc() drm/bridge: add support for refcounting drm/bridge: deprecate old-style bridge allocation drm/bridge: ti-sn65dsi83: use dynamic lifetime management drm/bridge: samsung-dsim: use dynamic lifetime management drivers/gpu/drm/bridge/samsung-dsim.c | 7 ++- drivers/gpu/drm/bridge/ti-sn65dsi83.c | 7 ++- drivers/gpu/drm/drm_bridge.c | 96 +++++++++++++++++++++++++++++++++++ include/drm/drm_bridge.h | 36 +++++++++++++ 4 files changed, 138 insertions(+), 8 deletions(-) --- base-commit: c940d00c7306a77ec293661abca634756207c885 change-id: 20250314-drm-bridge-refcount-58d9503503f6 Best regards,