From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752219AbbEDPPH (ORCPT ); Mon, 4 May 2015 11:15:07 -0400 Received: from mail-lb0-f175.google.com ([209.85.217.175]:34302 "EHLO mail-lb0-f175.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751873AbbEDPNo (ORCPT ); Mon, 4 May 2015 11:13:44 -0400 From: Johan Hovold To: Linus Walleij Cc: Alexandre Courbot , linux-gpio@vger.kernel.org, linux-kernel@vger.kernel.org, Johan Hovold Subject: [PATCH v2 10/23] gpio: sysfs: release irq after class-device deregistration Date: Mon, 4 May 2015 17:10:35 +0200 Message-Id: <1430752248-15401-11-git-send-email-johan@kernel.org> X-Mailer: git-send-email 2.0.5 In-Reply-To: <1430752248-15401-1-git-send-email-johan@kernel.org> References: <1430752248-15401-1-git-send-email-johan@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Make sure to release any irq only after the class device has been deregistered. This avoids a race between gpiod_unexport and edge_store, where an irq could be allocated just before the gpio class device is deregistered without relying on FLAG_EXPORT and the global sysfs lock. Note that there is no need to hold the sysfs lock when releasing the irq after the class device is gone as kernfs will prevent further attribute operations. Signed-off-by: Johan Hovold --- drivers/gpio/gpiolib-sysfs.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/drivers/gpio/gpiolib-sysfs.c b/drivers/gpio/gpiolib-sysfs.c index a78dabd4035b..e4b079eec9bc 100644 --- a/drivers/gpio/gpiolib-sysfs.c +++ b/drivers/gpio/gpiolib-sysfs.c @@ -695,7 +695,6 @@ void gpiod_unexport(struct gpio_desc *desc) dev = class_find_device(&gpio_class, NULL, desc, match_export); if (dev) { - gpio_setup_irq(desc, dev, 0); clear_bit(FLAG_SYSFS_DIR, &desc->flags); clear_bit(FLAG_EXPORT, &desc->flags); } else @@ -706,6 +705,11 @@ void gpiod_unexport(struct gpio_desc *desc) if (dev) { device_unregister(dev); + /* + * Release irq after deregistration to prevent race with + * edge_store. + */ + gpio_setup_irq(desc, dev, 0); put_device(dev); } -- 2.0.5