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 X-Spam-Level: X-Spam-Status: No, score=-6.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED,USER_AGENT_NEOMUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C7736C43381 for ; Tue, 12 Mar 2019 09:54:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9F65A2147C for ; Tue, 12 Mar 2019 09:54:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726078AbfCLJyh (ORCPT ); Tue, 12 Mar 2019 05:54:37 -0400 Received: from metis.ext.pengutronix.de ([85.220.165.71]:45873 "EHLO metis.ext.pengutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725882AbfCLJyg (ORCPT ); Tue, 12 Mar 2019 05:54:36 -0400 Received: from pty.hi.pengutronix.de ([2001:67c:670:100:1d::c5]) by metis.ext.pengutronix.de with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1h3e7G-0006vU-G8; Tue, 12 Mar 2019 10:54:34 +0100 Received: from ukl by pty.hi.pengutronix.de with local (Exim 4.89) (envelope-from ) id 1h3e7F-0007xm-Kf; Tue, 12 Mar 2019 10:54:33 +0100 Date: Tue, 12 Mar 2019 10:54:33 +0100 From: Uwe =?iso-8859-1?Q?Kleine-K=F6nig?= To: Geert Uytterhoeven Cc: Yoshihiro Shimoda , Thierry Reding , Linux PWM List , Linux-Renesas , Phong Hoang Subject: Re: [PATCH] pwm: Avoid deadlock warning when removing PWM device Message-ID: <20190312095433.fl2nbbj3jsqxhcny@pengutronix.de> References: <1552360594-21547-1-git-send-email-yoshihiro.shimoda.uh@renesas.com> <20190312092302.2x6zf4imlfsevmkr@pengutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: NeoMutt/20170113 (1.7.2) X-SA-Exim-Connect-IP: 2001:67c:670:100:1d::c5 X-SA-Exim-Mail-From: ukl@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-renesas-soc@vger.kernel.org Sender: linux-renesas-soc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-renesas-soc@vger.kernel.org On Tue, Mar 12, 2019 at 10:49:59AM +0100, Geert Uytterhoeven wrote: > Hi Uwe, > > On Tue, Mar 12, 2019 at 10:23 AM Uwe Kleine-König > wrote: > > On Tue, Mar 12, 2019 at 12:16:34PM +0900, Yoshihiro Shimoda wrote: > > > diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c > > > index 1581f6a..2fdd6611 100644 > > > --- a/drivers/pwm/core.c > > > +++ b/drivers/pwm/core.c > > > > @@ -368,10 +370,12 @@ int pwmchip_remove(struct pwm_chip *chip) > > > > > > free_pwms(chip); > > > > > > - pwmchip_sysfs_unexport(chip); > > > - > > > out: > > > mutex_unlock(&pwm_lock); > > > + > > > + if (!ret) > > > + pwmchip_sysfs_unexport(chip); > > > + > > > > I wonder if this needs to be done before free_pwms is called. Otherwise > > the pwmchip is already gone and then something is requested via sysfs. > > The chip itself is not freed, only the pwms array inside, which is not needed > for matching in pwmchip_sysfs_unexport(), right? OK, then make this: I wonder if pwmchip_sysfs_unexport needs to be done before free_pwms is called. Otherwise the PWMs's representation is already gone and then something might be requested via sysfs. Best regards Uwe -- Pengutronix e.K. | Uwe Kleine-König | Industrial Linux Solutions | http://www.pengutronix.de/ |