From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752674AbdAZMQY (ORCPT ); Thu, 26 Jan 2017 07:16:24 -0500 Received: from mail-wm0-f54.google.com ([74.125.82.54]:34232 "EHLO mail-wm0-f54.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752547AbdAZMQW (ORCPT ); Thu, 26 Jan 2017 07:16:22 -0500 Date: Thu, 26 Jan 2017 12:16:18 +0000 From: Lee Jones To: Arnd Bergmann Cc: Thierry Reding , Maxime Coquelin , Alexandre Torgue , Benjamin Gaignard , linux-pwm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] pwm: fix undefined behavior in stm32_pwm_apply Message-ID: <20170126121618.s66oob576faozd6z@dell> References: <20170125223155.1388582-1-arnd@arndb.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20170125223155.1388582-1-arnd@arndb.de> User-Agent: Mutt/1.6.2-neo (2016-08-21) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 25 Jan 2017, Arnd Bergmann wrote: > The stm32_pwm_apply randomly sets the polarity or doesn't, > as pointed out by this gcc warning: > > drivers/pwm/pwm-stm32.c: In function 'stm32_pwm_apply': > drivers/pwm/pwm-stm32.c:204:33: error: 'curstate.polarity' may be used uninitialized in this function [-Werror=maybe-uninitialized] > > I assume it was meant to compare the new state to the current > state rather than an uninitialized stack variable, so let's > do that instead. > > Fixes: bafffb6e7bd1 ("pwm: Add driver for STM32 plaftorm") > Signed-off-by: Arnd Bergmann > --- > drivers/pwm/pwm-stm32.c | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) Fix from the author already applied. > diff --git a/drivers/pwm/pwm-stm32.c b/drivers/pwm/pwm-stm32.c > index ce6232ebefe1..6139512aab7b 100644 > --- a/drivers/pwm/pwm-stm32.c > +++ b/drivers/pwm/pwm-stm32.c > @@ -189,7 +189,6 @@ static void stm32_pwm_disable(struct stm32_pwm *priv, int ch) > static int stm32_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, > struct pwm_state *state) > { > - struct pwm_state curstate; > bool enabled; > struct stm32_pwm *priv = to_stm32_pwm_dev(chip); > int ret; > @@ -201,7 +200,7 @@ static int stm32_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, > return 0; > } > > - if (state->polarity != curstate.polarity) > + if (state->polarity != pwm->state.polarity) > stm32_pwm_set_polarity(priv, pwm->hwpwm, state->polarity); > > ret = stm32_pwm_config(priv, pwm->hwpwm, -- Lee Jones Linaro STMicroelectronics Landing Team Lead Linaro.org │ Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog