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 2A425C19F2A for ; Mon, 8 Aug 2022 01:57:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S243534AbiHHB5k (ORCPT ); Sun, 7 Aug 2022 21:57:40 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52078 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S243661AbiHHBzp (ORCPT ); Sun, 7 Aug 2022 21:55:45 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6B6B01C10A; Sun, 7 Aug 2022 18:39:11 -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 ams.source.kernel.org (Postfix) with ESMTPS id 95E96B80E13; Mon, 8 Aug 2022 01:39:09 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7C6AFC433B5; Mon, 8 Aug 2022 01:39:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1659922748; bh=4pNbcfBY7sSXixtKDEXaS8TRXL9OvdOoDNaQXO+z7ao=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=kpAUNHvGpNYMskVola7uq2MUFIe59yXm9M922RHWguHcrrmzoJlVnslB+niJ0bNMZ 5yN54DWoTdY1w1AVYCqXFVUTkhNrhsvleToHYN83Prqmbzc1Yd+DGC7xALaTwI90RI TdHELLJV5oXwOE1ukaOuXvMTHfZjOv9PH6c3qMCpDk829yFl6RpkIbPECUL4TOVwDZ 1j6Uw/mxAI2wwdPGRewFFsCpomzRoScBvojTu0+TjpNSc3Y3LPwCXKxBOYQSWMMM/q hPhzb6bAQ4Kf88Nin4HVxbRkFmCjY4Apd2yhpQDW8olF20EHQz39uCaqJqxtOPmkBD 2HobYBlHobxJw== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: =?UTF-8?q?Uwe=20Kleine-K=C3=B6nig?= , Guenter Roeck , Sasha Levin , jdelvare@suse.com, linux-hwmon@vger.kernel.org Subject: [PATCH AUTOSEL 5.4 21/23] hwmon: (sht15) Fix wrong assumptions in device remove callback Date: Sun, 7 Aug 2022 21:38:28 -0400 Message-Id: <20220808013832.316381-21-sashal@kernel.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220808013832.316381-1-sashal@kernel.org> References: <20220808013832.316381-1-sashal@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-hwmon@vger.kernel.org From: Uwe Kleine-König [ Upstream commit 7d4edccc9bbfe1dcdff641343f7b0c6763fbe774 ] Taking a lock at the beginning of .remove() doesn't prevent new readers. With the existing approach it can happen, that a read occurs just when the lock was taken blocking the reader until the lock is released at the end of the remove callback which then accessed *data that is already freed then. To actually fix this problem the hwmon core needs some adaption. Until this is implemented take the optimistic approach of assuming that all readers are gone after hwmon_device_unregister() and sysfs_remove_group() as most other drivers do. (And once the core implements that, taking the lock would deadlock.) So drop the lock, move the reset to after device unregistration to keep the device in a workable state until it's deregistered. Also add a error message in case the reset fails and return 0 anyhow. (Returning an error code, doesn't stop the platform device unregistration and only results in a little helpful error message before the devm cleanup handlers are called.) Signed-off-by: Uwe Kleine-König Link: https://lore.kernel.org/r/20220725194344.150098-1-u.kleine-koenig@pengutronix.de Signed-off-by: Guenter Roeck Signed-off-by: Sasha Levin --- drivers/hwmon/sht15.c | 17 ++++++----------- 1 file changed, 6 insertions(+), 11 deletions(-) diff --git a/drivers/hwmon/sht15.c b/drivers/hwmon/sht15.c index 7f4a63959730..ae4d14257a11 100644 --- a/drivers/hwmon/sht15.c +++ b/drivers/hwmon/sht15.c @@ -1020,25 +1020,20 @@ static int sht15_probe(struct platform_device *pdev) static int sht15_remove(struct platform_device *pdev) { struct sht15_data *data = platform_get_drvdata(pdev); + int ret; - /* - * Make sure any reads from the device are done and - * prevent new ones beginning - */ - mutex_lock(&data->read_lock); - if (sht15_soft_reset(data)) { - mutex_unlock(&data->read_lock); - return -EFAULT; - } hwmon_device_unregister(data->hwmon_dev); sysfs_remove_group(&pdev->dev.kobj, &sht15_attr_group); + + ret = sht15_soft_reset(data); + if (ret) + dev_err(&pdev->dev, "Failed to reset device (%pe)\n", ERR_PTR(ret)); + if (!IS_ERR(data->reg)) { regulator_unregister_notifier(data->reg, &data->nb); regulator_disable(data->reg); } - mutex_unlock(&data->read_lock); - return 0; } -- 2.35.1