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,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 9A4AEC282CE for ; Thu, 18 Feb 2021 09:40:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6E8EB64D99 for ; Thu, 18 Feb 2021 09:40:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230444AbhBRJis (ORCPT ); Thu, 18 Feb 2021 04:38:48 -0500 Received: from ssl.serverraum.org ([176.9.125.105]:54585 "EHLO ssl.serverraum.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231258AbhBRI2A (ORCPT ); Thu, 18 Feb 2021 03:28:00 -0500 Received: from ssl.serverraum.org (web.serverraum.org [172.16.0.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ssl.serverraum.org (Postfix) with ESMTPSA id A1D1C22237; Thu, 18 Feb 2021 09:27:09 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=walle.cc; s=mail2016061301; t=1613636829; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=C6ZbUUwv9T7NP9ffAh1wNte4LqGASIxmIr4F8GWCA7w=; b=SXPm7qt685w7wZcv9GHdYeUZVNCIGcKmLTmjWiieUAe5ZW22euByvWUvNL7RsFL8hceqSu A+rwyr6S4oFB+nulbsn4hnV/VcFKHtfZLi7KvSg5/nY/gwXmM1EqOzG7Q01FUe/mO1ksyh 3ZDexrFxjuXJHX3/ZRQP5s64rBezfsk= MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Date: Thu, 18 Feb 2021 09:27:09 +0100 From: Michael Walle To: Greg KH Cc: Marc Zyngier , linux-kernel@vger.kernel.org, tglx@linutronix.de Subject: Re: [PATCH] irqdomain: remove debugfs_file from struct irq_domain In-Reply-To: References: <20210217195717.13727-1-michael@walle.cc> <4e4d0479b935e60a53f75ef534086476@kernel.org> <5c527bfb6f3dfe31b5c25f29418306c6@walle.cc> <87czwys6s1.wl-maz@kernel.org> User-Agent: Roundcube Webmail/1.4.10 Message-ID: <8b4de9eae773a43b38f42c8ab6d9d23c@walle.cc> X-Sender: michael@walle.cc Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. What has to happen before debugfs_lookup() can be called? Looks like someone has to initialize the static debugfs_mount, first. -michael