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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6313CC77B75 for ; Mon, 8 May 2023 10:15:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234294AbjEHKPN (ORCPT ); Mon, 8 May 2023 06:15:13 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44258 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234295AbjEHKPM (ORCPT ); Mon, 8 May 2023 06:15:12 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 855EF3A2A9 for ; Mon, 8 May 2023 03:15:11 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 1986362472 for ; Mon, 8 May 2023 10:15:11 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2C28DC433EF; Mon, 8 May 2023 10:15:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1683540910; bh=CiCQ4oLYF46ADq2hOVG06kJEsbvbYaGjgkcfshynec8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=VtCAaBppoklfpm3woLPUlTsXPkLpgYAa/LJgX0kbaKpBo4QRlRfbA0VbyXg+1Vo5U xdvkDsNnljrtXhx753FBqSd6DovPJHHfLq3CoefQPJN+RYPyXDevRZy7LTuqI4fsjQ qVFGWyTVGEb1pKGxcWB2rE74/2nN7OiYVO44VpAw= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Hans Verkuil , Linus Walleij , Sasha Levin Subject: [PATCH 6.1 544/611] pinctrl-bcm2835.c: fix race condition when setting gpio dir Date: Mon, 8 May 2023 11:46:26 +0200 Message-Id: <20230508094439.676116347@linuxfoundation.org> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20230508094421.513073170@linuxfoundation.org> References: <20230508094421.513073170@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Hans Verkuil [ Upstream commit b7badd752de05312fdb1aeb388480f706d0c087f ] In the past setting the pin direction called pinctrl_gpio_direction() which uses a mutex to serialize this. That was changed to set the direction directly in the pin controller driver, but that lost the serialization mechanism. Since the direction of multiple pins are in the same register you can have a race condition, something that was in fact observed with the cec-gpio driver. Add a new spinlock to serialize writing to the FSEL registers. Signed-off-by: Hans Verkuil Fixes: 1a4541b68e25 ("pinctrl-bcm2835: don't call pinctrl_gpio_direction()") Link: https://lore.kernel.org/r/4302b66b-ca20-0f19-d2aa-ee8661118863@xs4all.nl Signed-off-by: Linus Walleij Signed-off-by: Sasha Levin --- drivers/pinctrl/bcm/pinctrl-bcm2835.c | 19 +++++++++++++++---- 1 file changed, 15 insertions(+), 4 deletions(-) diff --git a/drivers/pinctrl/bcm/pinctrl-bcm2835.c b/drivers/pinctrl/bcm/pinctrl-bcm2835.c index c7cdccdb4332a..0f1ab0829ffe6 100644 --- a/drivers/pinctrl/bcm/pinctrl-bcm2835.c +++ b/drivers/pinctrl/bcm/pinctrl-bcm2835.c @@ -90,6 +90,8 @@ struct bcm2835_pinctrl { struct pinctrl_gpio_range gpio_range; raw_spinlock_t irq_lock[BCM2835_NUM_BANKS]; + /* Protect FSEL registers */ + spinlock_t fsel_lock; }; /* pins are just named GPIO0..GPIO53 */ @@ -284,14 +286,19 @@ static inline void bcm2835_pinctrl_fsel_set( struct bcm2835_pinctrl *pc, unsigned pin, enum bcm2835_fsel fsel) { - u32 val = bcm2835_gpio_rd(pc, FSEL_REG(pin)); - enum bcm2835_fsel cur = (val >> FSEL_SHIFT(pin)) & BCM2835_FSEL_MASK; + u32 val; + enum bcm2835_fsel cur; + unsigned long flags; + + spin_lock_irqsave(&pc->fsel_lock, flags); + val = bcm2835_gpio_rd(pc, FSEL_REG(pin)); + cur = (val >> FSEL_SHIFT(pin)) & BCM2835_FSEL_MASK; dev_dbg(pc->dev, "read %08x (%u => %s)\n", val, pin, - bcm2835_functions[cur]); + bcm2835_functions[cur]); if (cur == fsel) - return; + goto unlock; if (cur != BCM2835_FSEL_GPIO_IN && fsel != BCM2835_FSEL_GPIO_IN) { /* always transition through GPIO_IN */ @@ -309,6 +316,9 @@ static inline void bcm2835_pinctrl_fsel_set( dev_dbg(pc->dev, "write %08x (%u <= %s)\n", val, pin, bcm2835_functions[fsel]); bcm2835_gpio_wr(pc, FSEL_REG(pin), val); + +unlock: + spin_unlock_irqrestore(&pc->fsel_lock, flags); } static int bcm2835_gpio_direction_input(struct gpio_chip *chip, unsigned offset) @@ -1248,6 +1258,7 @@ static int bcm2835_pinctrl_probe(struct platform_device *pdev) pc->gpio_chip = *pdata->gpio_chip; pc->gpio_chip.parent = dev; + spin_lock_init(&pc->fsel_lock); for (i = 0; i < BCM2835_NUM_BANKS; i++) { unsigned long events; unsigned offset; -- 2.39.2