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 C3392E95A67 for ; Sun, 8 Oct 2023 00:49:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234348AbjJHAtw (ORCPT ); Sat, 7 Oct 2023 20:49:52 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40756 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234268AbjJHAtp (ORCPT ); Sat, 7 Oct 2023 20:49:45 -0400 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F3453199; Sat, 7 Oct 2023 17:49:23 -0700 (PDT) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5DF8BC433CD; Sun, 8 Oct 2023 00:49:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1696726162; bh=ZxLTp2cbLb9eo1xQ5FrKJgFWIe79ItBd51kd3aNbBl8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=QpEXjBFfBTwfAD7tMfVSur/dauE0S90dvAfT19Z+Vq3WjoY60V336UlEmVw9t5BeR iF6XX2VY/6QnoPks8yDP23ueP3iJLt7WxFkVSlVX72GpAouTWj+SL7QCamjDIR2FQ9 sqXLbBxCldMc8BWrQR5vyIsokhJHJiVnp2teVFBTjkxLIV8A0/LNYuz8Kz+a0JNHS2 3QEUfmVzAxlx+t7bSgLiPXb8QXFqtIVXYr5AF/KYg/tFf/3BJQWsmpdxgvbSmpEhgY nXVhA64/AQ+xtto92oXauFfbc9Sw8YH4ySFcZuUhzWKxXRvPmKcaPhZ+/gpIwxARIQ d3D6yKvKmfKWQ== 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 6.5 15/18] gpio: timberdale: Fix potential deadlock on &tgpio->lock Date: Sat, 7 Oct 2023 20:48:49 -0400 Message-Id: <20231008004853.3767621-15-sashal@kernel.org> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20231008004853.3767621-1-sashal@kernel.org> References: <20231008004853.3767621-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-stable-base: Linux 6.5.6 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 de14949a3fe5a..92c1f2baa4bff 100644 --- a/drivers/gpio/gpio-timberdale.c +++ b/drivers/gpio/gpio-timberdale.c @@ -43,9 +43,10 @@ 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) @@ -54,7 +55,7 @@ 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