From nobody Sat Feb 7 12:19:36 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 6D6332DCBE3 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=1760009967; cv=none; b=Dc/F50qrqO7foleixePFIVmoyUNq3yc3jG1R++v1WOSAppv5QTPaCjmIalnVBxfl4h+ttTXTXjaIWgb1VJmZh0Bg25rHnqR6REoopWLwz/nJsPvf3WoqmxelitTlHBWXyUnJLpz00CInJxDmjMwqSQquBEaeDGPL5DcB5UC7tKE= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760009967; c=relaxed/simple; bh=wQVXl6OvZb8Ck1Xm6iqpbtN3/PkZA4C4GtiodaggoLk=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=Sky2EVvFsz0wUH/VFYwkjlqWv41rdfoW7NXsBLFQdIxWnangYlZSNdqsV12oTg8nwB9uEw45N0qp1lhMpDyVAV6eyorCbRH2E1Rsb5qqEVIWgJwZIPZj5BI5NZomqGHL0Hu7mZsz6lfeXwnvZ7FDFXfsfNqzxx/9lEo8a+yNsbE= 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=QFMsvjrR; 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="QFMsvjrR" Received: from smtpout-01.galae.net (smtpout-01.galae.net [212.83.139.233]) by smtpout-04.galae.net (Postfix) with ESMTPS id 246C4C035A6; Thu, 9 Oct 2025 11:39:04 +0000 (UTC) Received: from mail.galae.net (mail.galae.net [212.83.136.155]) by smtpout-01.galae.net (Postfix) with ESMTPS id AF0BE6062C; Thu, 9 Oct 2025 11:39:22 +0000 (UTC) Received: from [127.0.0.1] (localhost [127.0.0.1]) by localhost (Mailerdaemon) with ESMTPSA id 28950102F21B6; Thu, 9 Oct 2025 13:39:19 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=dkim; t=1760009961; h=from:subject:date:message-id:to:cc:mime-version:content-type: content-transfer-encoding:in-reply-to:references; bh=BD8pO2vjph10EPQeLoSgNYytCgMXgCKx/eXc4dPQitE=; b=QFMsvjrRXXJAssZzomnw7eR3oUWhyXs9YikFK1Z59KfiWZSa968jrZzrT1pFxnWeoqjcjl 7yI5k986Uqsh2Q0hcUuarZwCd3IcezMS63wkLDoGnp1GVRjWgND3RpdpmCyxFf0jdn7hvE HnT7fj+SK1Ci84SY1Tf0NrEUrcpaHuee8ZFORHmeaqjes3uI2acoJlkGPWgo6+NWyZJkuw DRyzvcxz8p+SFM1X4tqJcrzM92iTWEYEEd2SCfLGteM0qgZCwYDcLXQ5hVVKXMtVNZxWTt DI4zLbtPX5Ney/xGWJH3V+AUeKALWCLLBmRfOOQ9twovSwSPcQHwoFDHsy1F6A== From: Luca Ceresoli Date: Thu, 09 Oct 2025 13:38:58 +0200 Subject: [PATCH v3 3/7] drm/bridge: drm_bridge_attach: lock the encoder chain mutex during insertion 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-v3-3-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 drm_bridge_attach() modifies the encoder bridge chain, so take a mutex around such operations to allow users of the chain to protect themselves from chain modifications while iterating. Signed-off-by: Luca Ceresoli Reviewed-by: Maxime Ripard --- Changes in v3: - Lock encoder->bridge_chain_mutex directly, no wrappers Changes in v2: - Removed comment before on drm_bridge_detach() --- drivers/gpu/drm/drm_bridge.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/gpu/drm/drm_bridge.c b/drivers/gpu/drm/drm_bridge.c index 53e7ece36dd940aabd1c0880f296fce7224a12ac..a25e379237f95c037eddc7602d4= 05f958a4efa44 100644 --- a/drivers/gpu/drm/drm_bridge.c +++ b/drivers/gpu/drm/drm_bridge.c @@ -453,10 +453,12 @@ int drm_bridge_attach(struct drm_encoder *encoder, st= ruct drm_bridge *bridge, bridge->dev =3D encoder->dev; bridge->encoder =3D encoder; =20 + mutex_lock(&encoder->bridge_chain_mutex); if (previous) list_add(&bridge->chain_node, &previous->chain_node); else list_add(&bridge->chain_node, &encoder->bridge_chain); + mutex_unlock(&encoder->bridge_chain_mutex); =20 if (bridge->funcs->attach) { ret =3D bridge->funcs->attach(bridge, encoder, flags); @@ -487,7 +489,9 @@ int drm_bridge_attach(struct drm_encoder *encoder, stru= ct drm_bridge *bridge, err_reset_bridge: bridge->dev =3D NULL; bridge->encoder =3D NULL; + mutex_lock(&encoder->bridge_chain_mutex); list_del(&bridge->chain_node); + mutex_unlock(&encoder->bridge_chain_mutex); =20 if (ret !=3D -EPROBE_DEFER) DRM_ERROR("failed to attach bridge %pOF to encoder %s: %d\n", --=20 2.51.0