From nobody Sun Feb 8 18:30:03 2026 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 7B88F350A30 for ; Tue, 13 Jan 2026 18:47:32 +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=1768330057; cv=none; b=A2J4V3tFnHgYBkR3N1SOp6WnBXUls9codXYEG0+KealTrV1nWUCE7/oWKAtjdx92xEC2PbjiQDDVIrRvAQuTyoI4un+h52P7qTZVouv1GCXGjamhlc7vWMPhd40fRBkkPSVDqOMmY6Ch5EPgRmwdlJZZHStgN+tIwWDDomAFsUU= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768330057; c=relaxed/simple; bh=upvhPfyn+JVl4Hja1gb44M2vssMH5uTTbAx7+q6uksY=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=nfuhV/wUFwATDyLeUgbs2+qjo42u599yO99OQlpuBy/KD1DitjPqi+G3Jv37CBAhtL0T4GOivqlDXbmOc10QtMm2sF5FOHbrnk3/w9pLwEYBUKG7spNFO5rVkSNt7DHMESJ79AUeRNEIMvbGgkGaGxQXWisQe6T5Z/USHt2bNs8= 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=GXlrOr4B; 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="GXlrOr4B" Received: from smtpout-01.galae.net (smtpout-01.galae.net [212.83.139.233]) by smtpout-02.galae.net (Postfix) with ESMTPS id 3CD381A283F; Tue, 13 Jan 2026 18:47:31 +0000 (UTC) Received: from mail.galae.net (mail.galae.net [212.83.136.155]) by smtpout-01.galae.net (Postfix) with ESMTPS id 12C846075E; Tue, 13 Jan 2026 18:47:31 +0000 (UTC) Received: from [127.0.0.1] (localhost [127.0.0.1]) by localhost (Mailerdaemon) with ESMTPSA id 87F9D103C86C8; Tue, 13 Jan 2026 19:47:28 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=dkim; t=1768330050; h=from:subject:date:message-id:to:cc:mime-version:content-type: content-transfer-encoding:in-reply-to:references; bh=f8N3qyeeBYvZN6dxPwZvCgRYBZLTW6nUvSaqWwv7hlc=; b=GXlrOr4BAmTXttD9zipKagl1R3I5eh5jusYVdzJokmF4UDMINVPIk8njA4NXv/6iZuaLe5 P65Iv7tpIayesvyCRc43rXc6R713fh5P1TpqK70Hg+LEizIVzSJsszsDWBtfLG0ZN3F0fx j+OqkicZOCDS0dzEBxXXjizzPGW7cLhoWydX+6wa4X2qmuZGc5g2QOVKMlV2845hRPfmje jKLSn+dM3F7MRhrCoNCuHrZlKdzgGLmIRGjuwsvjV1ZIeIrFjgH4GXiSV/03ujwZ7NWA64 hZmpOchxC2Bs9xtCMr5Kom2Fxmub9THbJLWbu6JgWFSJSopa/OGnFr0bcML6bg== From: Luca Ceresoli Date: Tue, 13 Jan 2026 19:47:14 +0100 Subject: [PATCH RESEND v4 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: <20260113-drm-bridge-alloc-encoder-chain-mutex-v4-3-60f3135adc45@bootlin.com> References: <20260113-drm-bridge-alloc-encoder-chain-mutex-v4-0-60f3135adc45@bootlin.com> In-Reply-To: <20260113-drm-bridge-alloc-encoder-chain-mutex-v4-0-60f3135adc45@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 , Ian Ray X-Mailer: b4 0.14.3 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. Reviewed-by: Maxime Ripard Signed-off-by: Luca Ceresoli --- 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 8f355df883d8..c8389383e0d2 100644 --- a/drivers/gpu/drm/drm_bridge.c +++ b/drivers/gpu/drm/drm_bridge.c @@ -462,10 +462,12 @@ 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); @@ -496,7 +498,9 @@ 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 2.52.0