From nobody Thu Dec 18 04:58:00 2025 Received: from smtpout-03.galae.net (smtpout-03.galae.net [185.246.85.4]) (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 86B283570A0 for ; Tue, 11 Nov 2025 12:01:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=185.246.85.4 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762862501; cv=none; b=kY5Uw5vq3xViM/2m/+o+h2zW6ckYPm4UEdJtLBmJfbygU6FtKSZMAFfE4EUffCNWH0NZH6WiVu0G4bGzFll9h4Yh0UTeyQ3VLFOp1VbltD4ra2D1unFE5iLCZ6VNTD/Y64zn0ZJKUDe5A899d6+EGfXO3yxDPd9fBCI3biSNdAw= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762862501; c=relaxed/simple; bh=xUPpOKK7DQhW4FTyGwu88aTs6YPnXL36m4PzyQr2ymE=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=qtMisNPI8thVAYSrHC2shJqn2WoKt3TN+gj03YqiymaFYwaOUTZKTUGWedhmhr+khytSbeCfrL7pbWreBwlo6HgFGwL++eyI3FwadOAOA9SmHTn1V3YcGrUPVgsRUmOmuOKw8GmBfmBFmlROe1loiRMljdQh6ORsWcMy98AW6ec= 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=s0oWb7a4; arc=none smtp.client-ip=185.246.85.4 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="s0oWb7a4" Received: from smtpout-01.galae.net (smtpout-01.galae.net [212.83.139.233]) by smtpout-03.galae.net (Postfix) with ESMTPS id ECE4E4E41627; Tue, 11 Nov 2025 12:01:30 +0000 (UTC) Received: from mail.galae.net (mail.galae.net [212.83.136.155]) by smtpout-01.galae.net (Postfix) with ESMTPS id 9B7DC606FB; Tue, 11 Nov 2025 12:01:30 +0000 (UTC) Received: from [127.0.0.1] (localhost [127.0.0.1]) by localhost (Mailerdaemon) with ESMTPSA id 0CFF410371942; Tue, 11 Nov 2025 13:01:27 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=dkim; t=1762862489; h=from:subject:date:message-id:to:cc:mime-version:content-type: content-transfer-encoding:in-reply-to:references; bh=caYAPf6iewWTVEYkDv72AgsM1cq+8VKXAzMNFg+RhVE=; b=s0oWb7a4OaPHX0gRDTBb9NN711RRduEmHAIlDZHgEI7uj884WiJjMNm8TGid3RmPnpqD3b sFfCtnNYpIk2crGbwgl2oDooHeILJtD+qVKZE+JrdlRKys9JOxwR9rEIh0vfk4HOtH9wce n0+azbhIEfqoQF2ItveAiVljZZn17xA2AKmI7Bzp1VFrEEzK+ZkNUavs/4IatWx2PWzWeX LIR+4NeeZggmMhZImk/JPI1KhSaDlQoq1gGQzw6wgJOq7MF4UxsEPbjOj23xYqy6Wburnw /2Kw4U7vaTHAzDZsUYb118Zt+S09SFfDTz8Inw1SHsF5/P/2mohhl2aEUmtUlA== From: Luca Ceresoli Date: Tue, 11 Nov 2025 13:01:21 +0100 Subject: [PATCH v4 1/7] drm/encoder: add mutex to protect the bridge chain 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: <20251111-drm-bridge-alloc-encoder-chain-mutex-v4-1-12b13eb8c0f8@bootlin.com> References: <20251111-drm-bridge-alloc-encoder-chain-mutex-v4-0-12b13eb8c0f8@bootlin.com> In-Reply-To: <20251111-drm-bridge-alloc-encoder-chain-mutex-v4-0-12b13eb8c0f8@bootlin.com> To: Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , Andrzej Hajda , Neil Armstrong , Robert Foss , Laurent Pinchart , Jonas Karlman , Jernej Skrabec Cc: Hui Pu , Thomas Petazzoni , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, Luca Ceresoli X-Mailer: b4 0.14.2 X-Last-TLS-Session-Version: TLSv1.3 The per-encoder bridge chain is currently assumed to be static once it is fully initialized. Work is in progress to add hot-pluggable bridges, breaking that assumption. With bridge removal, the encoder chain can change without notice, removing tail bridges. This can be problematic while iterating over the chain. Add a mutex to be taken whenever looping or changing the encoder chain. Reviewed-by: Maxime Ripard Signed-off-by: Luca Ceresoli --- Changes in v3: - Removed the drm_encoder_chain_[un]lock() wrappers Changes in v2: - Added documentation to new APIs --- drivers/gpu/drm/drm_encoder.c | 2 ++ include/drm/drm_encoder.h | 4 ++++ 2 files changed, 6 insertions(+) diff --git a/drivers/gpu/drm/drm_encoder.c b/drivers/gpu/drm/drm_encoder.c index 8f2bc6a28482229fd0b030a1958f87753ad7885f..3261f142baea30c516499d23dbf= 8d0acf5952cd6 100644 --- a/drivers/gpu/drm/drm_encoder.c +++ b/drivers/gpu/drm/drm_encoder.c @@ -129,6 +129,7 @@ static int __drm_encoder_init(struct drm_device *dev, } =20 INIT_LIST_HEAD(&encoder->bridge_chain); + mutex_init(&encoder->bridge_chain_mutex); list_add_tail(&encoder->head, &dev->mode_config.encoder_list); encoder->index =3D dev->mode_config.num_encoder++; =20 @@ -202,6 +203,7 @@ void drm_encoder_cleanup(struct drm_encoder *encoder) kfree(encoder->name); list_del(&encoder->head); dev->mode_config.num_encoder--; + mutex_destroy(&encoder->bridge_chain_mutex); =20 memset(encoder, 0, sizeof(*encoder)); } diff --git a/include/drm/drm_encoder.h b/include/drm/drm_encoder.h index 977a9381c8ba943b4d3e021635ea14856df8a17d..eded7c34481a2e9b4a127300462= 7a03f4035b24f 100644 --- a/include/drm/drm_encoder.h +++ b/include/drm/drm_encoder.h @@ -25,6 +25,7 @@ =20 #include #include +#include #include #include #include @@ -189,6 +190,9 @@ struct drm_encoder { */ struct list_head bridge_chain; =20 + /** @bridge_chain_mutex: protect bridge_chain from changes while iteratin= g */ + struct mutex bridge_chain_mutex; + const struct drm_encoder_funcs *funcs; const struct drm_encoder_helper_funcs *helper_private; =20 --=20 2.51.1