From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id AB2DFC433F5 for ; Mon, 25 Oct 2021 19:56:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8C2B260C41 for ; Mon, 25 Oct 2021 19:56:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239981AbhJYT61 (ORCPT ); Mon, 25 Oct 2021 15:58:27 -0400 Received: from mail.kernel.org ([198.145.29.99]:42070 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238978AbhJYTxy (ORCPT ); Mon, 25 Oct 2021 15:53:54 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id D4C5661263; Mon, 25 Oct 2021 19:44:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1635191095; bh=wBMMXcHsacMg/RF9mmTos5XgdKFwCwBPUKoV0FrRWks=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=HeeGkB+9i/K1xlwVSylxCy4WOJyoXRJlEtQExoOMy+vxcEz3v/3i+jGPjo4E3rGAd PQIr9WQPSKgA2X+8dglNMT32w8BSQNJhehBQcM9Qg5mCVySf4J/UDsWQgFSXeSOmO3 gCBWNreyRGnxNLbeT4A/Et+ZVFm5ui2YNCRuoBr0= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, =?UTF-8?q?Uwe=20Kleine-K=C3=B6nig?= , Mark Brown , Sasha Levin Subject: [PATCH 5.14 143/169] spi-mux: Fix false-positive lockdep splats Date: Mon, 25 Oct 2021 21:15:24 +0200 Message-Id: <20211025191035.702202966@linuxfoundation.org> X-Mailer: git-send-email 2.33.1 In-Reply-To: <20211025191017.756020307@linuxfoundation.org> References: <20211025191017.756020307@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Uwe Kleine-König [ Upstream commit 16a8e2fbb2d49111004efc1c7342e083eafabeb0 ] io_mutex is taken by spi_setup() and spi-mux's .setup() callback calls spi_setup() which results in a nested lock of io_mutex. add_lock is taken by spi_add_device(). The device_add() call in there can result in calling spi-mux's .probe() callback which registers its own spi controller which in turn results in spi_add_device() being called again. To fix this initialize the controller's locks already in spi_alloc_controller() to give spi_mux_probe() a chance to set the lockdep subclass. Signed-off-by: Uwe Kleine-König Link: https://lore.kernel.org/r/20211013133710.2679703-2-u.kleine-koenig@pengutronix.de Signed-off-by: Mark Brown Signed-off-by: Sasha Levin --- drivers/spi/spi-mux.c | 7 +++++++ drivers/spi/spi.c | 12 ++++++------ 2 files changed, 13 insertions(+), 6 deletions(-) diff --git a/drivers/spi/spi-mux.c b/drivers/spi/spi-mux.c index 9708b7827ff7..f5d32ec4634e 100644 --- a/drivers/spi/spi-mux.c +++ b/drivers/spi/spi-mux.c @@ -137,6 +137,13 @@ static int spi_mux_probe(struct spi_device *spi) priv = spi_controller_get_devdata(ctlr); priv->spi = spi; + /* + * Increase lockdep class as these lock are taken while the parent bus + * already holds their instance's lock. + */ + lockdep_set_subclass(&ctlr->io_mutex, 1); + lockdep_set_subclass(&ctlr->add_lock, 1); + priv->mux = devm_mux_control_get(&spi->dev, NULL); if (IS_ERR(priv->mux)) { ret = dev_err_probe(&spi->dev, PTR_ERR(priv->mux), diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c index 2c342bded058..3093e0041158 100644 --- a/drivers/spi/spi.c +++ b/drivers/spi/spi.c @@ -2549,6 +2549,12 @@ struct spi_controller *__spi_alloc_controller(struct device *dev, return NULL; device_initialize(&ctlr->dev); + INIT_LIST_HEAD(&ctlr->queue); + spin_lock_init(&ctlr->queue_lock); + spin_lock_init(&ctlr->bus_lock_spinlock); + mutex_init(&ctlr->bus_lock_mutex); + mutex_init(&ctlr->io_mutex); + mutex_init(&ctlr->add_lock); ctlr->bus_num = -1; ctlr->num_chipselect = 1; ctlr->slave = slave; @@ -2821,12 +2827,6 @@ int spi_register_controller(struct spi_controller *ctlr) return id; ctlr->bus_num = id; } - INIT_LIST_HEAD(&ctlr->queue); - spin_lock_init(&ctlr->queue_lock); - spin_lock_init(&ctlr->bus_lock_spinlock); - mutex_init(&ctlr->bus_lock_mutex); - mutex_init(&ctlr->io_mutex); - mutex_init(&ctlr->add_lock); ctlr->bus_lock_flag = 0; init_completion(&ctlr->xfer_completion); if (!ctlr->max_dma_len) -- 2.33.0