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=-10.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 B0543C433DB for ; Thu, 18 Feb 2021 10:38:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6274864EAD for ; Thu, 18 Feb 2021 10:38:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230224AbhBRJsV (ORCPT ); Thu, 18 Feb 2021 04:48:21 -0500 Received: from mail.kernel.org ([198.145.29.99]:45514 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231175AbhBRIjv (ORCPT ); Thu, 18 Feb 2021 03:39:51 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 6BDA464E68; Thu, 18 Feb 2021 08:38:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1613637513; bh=1hR5BWLjfPV6fbUMbks52LoRUvrgUKHL4ga3m4GQkYo=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=1EEr5PdcXw8QPVzAoN2V6EuToTn8Gou4iAkDhwzI/XNhGQ/rpSDojuInUHK5CxMzS 1Ni9gfha1dFKuVb73lLmCO2XiRiXuXZ4KdGThns3ielCfnWpB6IRA710xx1hSMmDwN rXpH1toXPiKvg2EUb4NGU5RUiDDG46gQXqRD1eMI= Date: Thu, 18 Feb 2021 09:38:30 +0100 From: Greg KH To: Michael Walle Cc: Marc Zyngier , linux-kernel@vger.kernel.org, tglx@linutronix.de Subject: Re: [PATCH] irqdomain: remove debugfs_file from struct irq_domain Message-ID: References: <20210217195717.13727-1-michael@walle.cc> <4e4d0479b935e60a53f75ef534086476@kernel.org> <5c527bfb6f3dfe31b5c25f29418306c6@walle.cc> <87czwys6s1.wl-maz@kernel.org> <8b4de9eae773a43b38f42c8ab6d9d23c@walle.cc> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <8b4de9eae773a43b38f42c8ab6d9d23c@walle.cc> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Feb 18, 2021 at 09:27:09AM +0100, Michael Walle wrote: > Am 2021-02-18 08:31, schrieb Greg KH: > > On Wed, Feb 17, 2021 at 09:50:38PM +0000, Marc Zyngier wrote: > > > On Wed, 17 Feb 2021 20:10:50 +0000, > > > Michael Walle wrote: > > > > > > > > Am 2021-02-17 21:02, schrieb Marc Zyngier: > > > > > On 2021-02-17 19:57, Michael Walle wrote: > > > > >> Hi Greg, > > > > >> > > > > >>> There's no need to keep around a dentry pointer to a simple file that > > > > >>> debugfs itself can look up when we need to remove it from the system. > > > > >>> So simplify the code by deleting the variable and cleaning up the > > > > >>> logic > > > > >>> around the debugfs file. > > > > >> > > > > >> This will generate the following oops on my board (arm64, > > > > >> freescale/fsl-ls1028a-kontron-sl28-var3-ads2.dts). In debugfs_lookup() > > > > >> debugfs_mount is NULL. > > > > > > > > > > That's odd. I gave it a go yesterday, and nothing blew up. > > > > > Which makes me wonder whether I had the debug stuff enabled > > > > > the first place... > > > > > > > > > > I've dropped the patch from -next for now until I figure it out > > > > > (probably tomorrow). > > > > > > > > Mh, maybe its my .config, I've attached it. I also noticed that > > > > the board boots just fine in our kernel-ci [1]. > > > > > > I reproduced here. I had disabled GENERIC_IRQ_DEBUGFS for obscure > > > reasons, and it caught fire as I re-enabled it. > > > > > > Adding this fixes it for me: > > > > > > diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c > > > index 367ff1c35f75..d8a14cf1a7b6 100644 > > > --- a/kernel/irq/irqdomain.c > > > +++ b/kernel/irq/irqdomain.c > > > @@ -1904,7 +1904,8 @@ static void debugfs_add_domain_dir(struct > > > irq_domain *d) > > > > > > static void debugfs_remove_domain_dir(struct irq_domain *d) > > > { > > > - debugfs_remove(debugfs_lookup(d->name, domain_dir)); > > > + if (domain_dir) > > > + debugfs_remove(debugfs_lookup(d->name, domain_dir)); > > > } > > > > > > void __init irq_domain_debugfs_init(struct dentry *root) > > > > > > > > > Could you please check whether it works for you? > > > > Can you try this debugfs core change instead? Callers to debugfs should > > not have to do the above type of checking as debugfs should be much more > > robust than that. > > > > thanks, > > > > greg k-h > > > > > > diff --git a/fs/debugfs/inode.c b/fs/debugfs/inode.c > > index 2fcf66473436..5aa798f52b6e 100644 > > --- a/fs/debugfs/inode.c > > +++ b/fs/debugfs/inode.c > > @@ -297,7 +297,7 @@ struct dentry *debugfs_lookup(const char *name, > > struct dentry *parent) > > { > > struct dentry *dentry; > > > > - if (IS_ERR(parent)) > > + if (IS_ERR_OR_NULL(name) || IS_ERR(parent)) > > return NULL; > > > > if (!parent) > > This doesn't work. name is not NULL when it is called. Ok, but it is a good check we need to make anyway, I'll add it to a patch series :) > What has to happen before debugfs_lookup() can be called? Looks like > someone has to initialize the static debugfs_mount, first. Wow, wait, you are removing a debugfs file _before_ debugfs is even initialized? Didn't expect that, ok, let me go try this again... thanks, greg k-h