From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:57796 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S966695AbcKXP2S (ORCPT ); Thu, 24 Nov 2016 10:28:18 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Patrice Chotard , Linus Walleij Subject: [PATCH 4.8 15/67] gpio: do not double-check direction on sleeping chips Date: Thu, 24 Nov 2016 16:27:09 +0100 Message-Id: <20161124145458.493977443@linuxfoundation.org> In-Reply-To: <20161124145457.061710350@linuxfoundation.org> References: <20161124145457.061710350@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: stable-owner@vger.kernel.org List-ID: 4.8-stable review patch. If anyone has any objections, please let me know. ------------------ From: Linus Walleij commit 60f8339eb388df8a46f8eb4282ff0e15f08f218c upstream. When locking a GPIO line as IRQ, we go to lengths to double-check that the line is really set as input before marking it as used for IRQ. This is not good on GPIO chips that can sleep, because this function is called in IRQ-safe context. Just skip this if it can't be checked quickly. Currently this happens on sleeping expanders such as STMPE or TC3589x: BUG: scheduling while atomic: swapper/1/0x00000002 Modules linked in: CPU: 0 PID: 1 Comm: swapper Not tainted 4.9.0-rc1+ #38 Hardware name: Nomadik STn8815 [] (unwind_backtrace) from [] (show_stack+0x10/0x14) [] (show_stack) from [] (__schedule_bug+0x54/0x80) [] (__schedule_bug) from [] (__schedule+0x3a0/0x460) [] (__schedule) from [] (schedule+0x54/0xb8) (...) This patch fixes that problem and relies on the direction read from the chip when it was added. Fixes: 9c10280d85c1 ("gpio: flush direction status in gpiochip_lock_as_irq()") Cc: Patrice Chotard Signed-off-by: Linus Walleij Signed-off-by: Greg Kroah-Hartman --- drivers/gpio/gpiolib.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -2667,8 +2667,11 @@ int gpiochip_lock_as_irq(struct gpio_chi if (IS_ERR(desc)) return PTR_ERR(desc); - /* Flush direction if something changed behind our back */ - if (chip->get_direction) { + /* + * If it's fast: flush the direction setting if something changed + * behind our back + */ + if (!chip->can_sleep && chip->get_direction) { int dir = chip->get_direction(chip, offset); if (dir)