From nobody Sat Feb 7 12:19:24 2026 Received: from smtpout-04.galae.net (smtpout-04.galae.net [185.171.202.116]) (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 6AC672D7DE5 for ; Thu, 9 Oct 2025 11:39:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=185.171.202.116 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760009966; cv=none; b=XoD3BwyR8ToZWxpPZCNiFOGM1eVQQeVkR8iNC2NzU24Z9lRzGpy7HKYCQNH0ulXCXWK5FR+53QlCGnvEAsXgdGi+lvx3tml9X6WSllzi3Kp+LXJPyGeV6IC2JGPJdh0I8zc329QDFNBrHs2jX3i1wFkTqh04/rHtd3Xt7I1XjxA= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760009966; c=relaxed/simple; bh=maEkPxciNRj0q+f5j17JeBW/u7CNxjTUZ7pppeDlfIo=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=YO1U0XlpDAJNSOS6xMA8tei+R51Omr802esS8/40EHELGsi/ThcUrS6/FAO27EcIH1rmwAvuG5LXwv9Zm9udRYLr5AcLrzeQ9J3lot9anhnfepSQxqqeQG2wYR+sD6CLcTwqyB4aTp00tMrRfNkW+FdnsibJLodn1EYHh16lKmc= 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=aQUj4nHv; arc=none smtp.client-ip=185.171.202.116 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="aQUj4nHv" Received: from smtpout-01.galae.net (smtpout-01.galae.net [212.83.139.233]) by smtpout-04.galae.net (Postfix) with ESMTPS id F2B9BC0359D; Thu, 9 Oct 2025 11:38:58 +0000 (UTC) Received: from mail.galae.net (mail.galae.net [212.83.136.155]) by smtpout-01.galae.net (Postfix) with ESMTPS id 86FE96062C; Thu, 9 Oct 2025 11:39:17 +0000 (UTC) Received: from [127.0.0.1] (localhost [127.0.0.1]) by localhost (Mailerdaemon) with ESMTPSA id 2CA2D102F21D1; Thu, 9 Oct 2025 13:39:14 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=dkim; t=1760009956; h=from:subject:date:message-id:to:cc:mime-version:content-type: content-transfer-encoding:in-reply-to:references; bh=AwYCkGNcORGbBTMYr3nyq+d2grRy53+g1LRUgh49gfo=; b=aQUj4nHvlMNcQkFMJJv/WyPV2Wy+5OMmMqu2CI+oAXaekoHjJjosmwmZxH3GdU5A525/Pt hAuHiaG5QDWtPws0gvbXWY/3tGZJcv4r1ScROv0F4mJJcKsrYLJdDXXpnoiBjc8j8PdIb6 U2zZkP3w3TVV2rlt6oE6sCTVDKBU/7M8oD4bpbOQSw+y8nImfRpNJcLr2SjIIlb7OcRI0j CJG0HD9ukAlCIzGNsmq2rVhnRbOXVH82+2q80/ap6Zfkhmr/5bN1zHVEprHZ7OdDMNQg9j hzOzwsW2azECrbaK90+/fgAq1rYPbeBtXNG1HByp9LaOq7Xe0j1fu82LkHKf/w== From: Luca Ceresoli Date: Thu, 09 Oct 2025 13:38:56 +0200 Subject: [PATCH v3 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: <20251009-drm-bridge-alloc-encoder-chain-mutex-v3-1-c90ed744efec@bootlin.com> References: <20251009-drm-bridge-alloc-encoder-chain-mutex-v3-0-c90ed744efec@bootlin.com> In-Reply-To: <20251009-drm-bridge-alloc-encoder-chain-mutex-v3-0-c90ed744efec@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. Signed-off-by: Luca Ceresoli Reviewed-by: Maxime Ripard --- 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 2.51.0