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 1794AE95A85 for ; Sun, 8 Oct 2023 00:52:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234545AbjJHAwc (ORCPT ); Sat, 7 Oct 2023 20:52:32 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34670 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234498AbjJHAv6 (ORCPT ); Sat, 7 Oct 2023 20:51:58 -0400 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6C2CF10F3; Sat, 7 Oct 2023 17:51:02 -0700 (PDT) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 63739C116A8; Sun, 8 Oct 2023 00:50:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1696726249; bh=QDVzUF3cOMu7w7hpekSFODjxqlS2FUSLsjhjkAhG8F4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=I1RCxZaLahKZ0PFWYtpdaeqlwH4bjySPRhA0uGOCtFVq9gUUvAeQT2sKHxhLrHNdw 9vgBzhkVi7RP17q11saQCWQbWZJBnUmZ7jOAvV4EzQJ1DKYIVYE0lRwdMb7k1qps32 tM0NrUsxNE9ZumocLcJb4qkDy1JxsTJdu3oBPrUlU3H2HHG3LBFlZ7fVvVZSxCjU9/ SPnmtmaQzxsC2F/27zJdOydqw6I/UQvq4uYNt7GyITaWxuBlmBxgtaSjaWQVK3y6FF /7R7R7gb8qvCOkAjsvq5qWXd7UqQrfidnsK6ouVfhSjdu4sSGzkGjbhxBkUtew7X44 sgOIYSX/wUtCQ== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Chengfeng Ye , Andy Shevchenko , Bartosz Golaszewski , Sasha Levin , linus.walleij@linaro.org, brgl@bgdev.pl, linux-gpio@vger.kernel.org Subject: [PATCH AUTOSEL 4.19 6/8] gpio: timberdale: Fix potential deadlock on &tgpio->lock Date: Sat, 7 Oct 2023 20:50:36 -0400 Message-Id: <20231008005039.3768522-6-sashal@kernel.org> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20231008005039.3768522-1-sashal@kernel.org> References: <20231008005039.3768522-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-stable-base: Linux 4.19.295 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-gpio@vger.kernel.org From: Chengfeng Ye [ Upstream commit 9e8bc2dda5a7a8e2babc9975f4b11c9a6196e490 ] As timbgpio_irq_enable()/timbgpio_irq_disable() callback could be executed under irq context, it could introduce double locks on &tgpio->lock if it preempts other execution units requiring the same locks. timbgpio_gpio_set() --> timbgpio_update_bit() --> spin_lock(&tgpio->lock) --> timbgpio_irq_disable() --> spin_lock_irqsave(&tgpio->lock) This flaw was found by an experimental static analysis tool I am developing for irq-related deadlock. To prevent the potential deadlock, the patch uses spin_lock_irqsave() on &tgpio->lock inside timbgpio_gpio_set() to prevent the possible deadlock scenario. Signed-off-by: Chengfeng Ye Reviewed-by: Andy Shevchenko Signed-off-by: Bartosz Golaszewski Signed-off-by: Sasha Levin --- drivers/gpio/gpio-timberdale.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/drivers/gpio/gpio-timberdale.c b/drivers/gpio/gpio-timberdale.c index 314e300d6ba33..1e6925c27ae29 100644 --- a/drivers/gpio/gpio-timberdale.c +++ b/drivers/gpio/gpio-timberdale.c @@ -55,9 +55,10 @@ static int timbgpio_update_bit(struct gpio_chip *gpio, unsigned index, unsigned offset, bool enabled) { struct timbgpio *tgpio = gpiochip_get_data(gpio); + unsigned long flags; u32 reg; - spin_lock(&tgpio->lock); + spin_lock_irqsave(&tgpio->lock, flags); reg = ioread32(tgpio->membase + offset); if (enabled) @@ -66,7 +67,7 @@ static int timbgpio_update_bit(struct gpio_chip *gpio, unsigned index, reg &= ~(1 << index); iowrite32(reg, tgpio->membase + offset); - spin_unlock(&tgpio->lock); + spin_unlock_irqrestore(&tgpio->lock, flags); return 0; } -- 2.40.1