From nobody Mon Dec 1 22:36:47 2025 Received: from smtpout-02.galae.net (smtpout-02.galae.net [185.246.84.56]) (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 8F22D2C3745; Fri, 28 Nov 2025 16:52:13 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=185.246.84.56 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764348735; cv=none; b=NPkkQLIc2Io5EaJmIv5Pu+VwRf1Sj7w6qlYc6lSwZiOCpfE0TsUc4mdoo7syhym4ns3fAGTRUC8SGN30BlSVIq+7LskzRlBX8HxmvtpbSqbhea4fzCuZckMhm53yb4QzNZQtZ3BnTV6cfnw/EulgwEchAgEsznXl8H+zUUCEUI4= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764348735; c=relaxed/simple; bh=a28O65zJJ8vlr1pJAymt5fViUg/VFCSTL4/O6DWmqX4=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=HNjVzi1vElPXEHZnX+//ygOcFVooN392OXdtxmhQ5IlRJlX+CiUpPD7p9rKkRAWfJsFeFYjrK7zCo2kdba64H8n6WpSxB5IHvMPTreX83I2MyIYzSa2rJ4SPbi2/L3Hnap2dN2/FgKOHWDOF1p/2YQSIZFJUBLA2+WrjvT+xwSg= 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=gTVRc4jI; arc=none smtp.client-ip=185.246.84.56 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="gTVRc4jI" Received: from smtpout-01.galae.net (smtpout-01.galae.net [212.83.139.233]) by smtpout-02.galae.net (Postfix) with ESMTPS id EB62A1A1E0A; Fri, 28 Nov 2025 16:52:11 +0000 (UTC) Received: from mail.galae.net (mail.galae.net [212.83.136.155]) by smtpout-01.galae.net (Postfix) with ESMTPS id BE9DB60706; Fri, 28 Nov 2025 16:52:11 +0000 (UTC) Received: from [127.0.0.1] (localhost [127.0.0.1]) by localhost (Mailerdaemon) with ESMTPSA id 1530F10B02182; Fri, 28 Nov 2025 17:52:01 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=dkim; t=1764348729; h=from:subject:date:message-id:to:cc:mime-version:content-type: content-transfer-encoding:in-reply-to:references; bh=Dos6302sw2So3HCMKlOnU1oeuTLRBWiOqCj3ANH3duY=; b=gTVRc4jIQbSVuZSruHuqCi4PEzEVqNIsOqB/pobzsLxJGQ/BX/lrepbwGEQlJUFaR5Uy8D F65rtaYzVtWxJEn22HEHS5rPX7u5cfo+cd9VQbZeCpCFrV5961Gly1Dn/glTI5ltrUYah0 Pnx/W3GeunwEIZKKo4nJ/3AVAScQqKpb9nrNfrQn5+gSELusr5+TtPwSfjeCdZxPxDrlcc Duiz45LTGQm0ePwiO9tq/e6aCfdoBw8revE9kSMKLgECBcP8UCofbbFN7zjEKtFpiQND7B gDM3prJ3qXL78s9Sc5EzgPfdljim8S4SRk2mEtdLr54ihhUOVnAGhxXLvxlw+g== From: Luca Ceresoli Date: Fri, 28 Nov 2025 17:50:12 +0100 Subject: [PATCH v2 02/26] drm/bridge: deprecate of_drm_find_bridge() 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: quoted-printable Message-Id: <20251128-drm-bridge-alloc-getput-drm_of_find_bridge-v2-2-88f8a107eca2@bootlin.com> References: <20251128-drm-bridge-alloc-getput-drm_of_find_bridge-v2-0-88f8a107eca2@bootlin.com> In-Reply-To: <20251128-drm-bridge-alloc-getput-drm_of_find_bridge-v2-0-88f8a107eca2@bootlin.com> To: Andrzej Hajda , Neil Armstrong , Robert Foss , Laurent Pinchart , Jonas Karlman , Jernej Skrabec , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , Jonathan Corbet , Alexey Brodkin , Phong LE , Liu Ying , Shawn Guo , Sascha Hauer , Pengutronix Kernel Team , Fabio Estevam , Adrien Grassein , Laurent Pinchart , Tomi Valkeinen , Kieran Bingham , Geert Uytterhoeven , Magnus Damm , Kevin Hilman , Jerome Brunet , Martin Blumenstingl , Chun-Kuang Hu , Philipp Zabel , Matthias Brugger , AngeloGioacchino Del Regno , Anitha Chrisanthus , Inki Dae , Seung-Woo Kim , Kyungmin Park , Krzysztof Kozlowski , Alim Akhtar Cc: Hui Pu , Thomas Petazzoni , Louis Chauvet , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, imx@lists.linux.dev, linux-arm-kernel@lists.infradead.org, linux-renesas-soc@vger.kernel.org, linux-amlogic@lists.infradead.org, linux-mediatek@lists.infradead.org, linux-samsung-soc@vger.kernel.org, Luca Ceresoli X-Mailer: b4 0.14.3 X-Last-TLS-Session-Version: TLSv1.3 of_drm_find_bridge() does not increment the returned bridge refcount. of_drm_get_bridge() is to be used as a replacement. Suggested-by: Maxime Ripard Link: https://lore.kernel.org/dri-devel/20250319-stylish-lime-mongoose-0a18= ad@houat/ Signed-off-by: Luca Ceresoli --- Changes in v2: - expand comment to mention why this function is dangerous and what users should do about refcounting --- drivers/gpu/drm/drm_bridge.c | 18 ++++++++++++++++-- 1 file changed, 16 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/drm_bridge.c b/drivers/gpu/drm/drm_bridge.c index 367b7a3d8aa3..21a84715d221 100644 --- a/drivers/gpu/drm/drm_bridge.c +++ b/drivers/gpu/drm/drm_bridge.c @@ -299,7 +299,7 @@ EXPORT_SYMBOL(__devm_drm_bridge_alloc); * @bridge: bridge control structure * * Add the given bridge to the global list of bridges, where they can be - * found by users via of_drm_find_bridge(). + * found by users via of_drm_get_bridge(). * * The bridge to be added must have been allocated by * devm_drm_bridge_alloc(). @@ -360,7 +360,7 @@ EXPORT_SYMBOL(devm_drm_bridge_add); * @bridge: bridge control structure * * Remove the given bridge from the global list of registered bridges, so - * it won't be found by users via of_drm_find_bridge(), and add it to the + * it won't be found by users via of_drm_get_bridge(), and add it to the * lingering bridge list, to keep track of it until its allocated memory is * eventually freed. */ @@ -1448,6 +1448,20 @@ EXPORT_SYMBOL(of_drm_get_bridge); * * @np: device node * + * This function is deprecated. Convert to of_drm_get_bridge() instead for + * proper refcounting. + * + * The bridge returned by this function is not refcounted. This is + * dangerous because the bridge might be deallocated even before the caller + * has a chance to use it. To use this function you have to do one of: + * - get a reference with drm_bridge_get() as soon as possible to + * minimize the race window, and then drm_bridge_put() when no longer + * using the pointer + * - not call drm_bridge_get() or drm_bridge_put() at all, which used to + * be the correct practice before dynamic bridge lifetime was introduced + * - again, convert to of_drm_get_bridge(), which is the only safe thing + * to do + * * RETURNS: * drm_bridge control struct on success, NULL on failure */ --=20 2.51.1