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 31604C433E0 for ; Thu, 18 Feb 2021 10:19:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DBC1864E85 for ; Thu, 18 Feb 2021 10:19:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230166AbhBRKN2 (ORCPT ); Thu, 18 Feb 2021 05:13:28 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33236 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231497AbhBRJFa (ORCPT ); Thu, 18 Feb 2021 04:05:30 -0500 Received: from ssl.serverraum.org (ssl.serverraum.org [IPv6:2a01:4f8:151:8464::1:2]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 718FFC061756 for ; Thu, 18 Feb 2021 01:04:47 -0800 (PST) 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 914D122237; Thu, 18 Feb 2021 10:04:45 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=walle.cc; s=mail2016061301; t=1613639085; 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=GykWYuyBcF2vP89Zq9UF2qH/9MD0E9Mi10jyqTqB2j8=; b=lKni24ndC1dJrMokiMmvgXRGsqvz+OdQ/qrqS2l/0qZDsiyKRES5xRq8zPGfS8fAP0E+Ad AZV5LrUWdWp53E1SYOm9N4C8nKmx3GnAS4cdWPOvKKATa7nUrtcyWy/sfwi/OgrvjZtlbn uQVghbOmEDbJHE07euFXXMe61PuX1ZI= MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Date: Thu, 18 Feb 2021 10:04:45 +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> <8b4de9eae773a43b38f42c8ab6d9d23c@walle.cc> User-Agent: Roundcube Webmail/1.4.10 Message-ID: X-Sender: michael@walle.cc Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Am 2021-02-18 09:52, schrieb Greg KH: > 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. >> >> What has to happen before debugfs_lookup() can be called? Looks like >> someone has to initialize the static debugfs_mount, first. > > Ok, how about this: > > > diff --git a/fs/debugfs/inode.c b/fs/debugfs/inode.c > index 2fcf66473436..86c7f0489620 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 (!debugfs_initialized() || IS_ERR_OR_NULL(name) || IS_ERR(parent)) > return NULL; > > if (!parent) > @@ -318,6 +318,9 @@ static struct dentry *start_creating(const char > *name, struct dentry *parent) > if (!(debugfs_allow & DEBUGFS_ALLOW_API)) > return ERR_PTR(-EPERM); > > + if (!debugfs_initialized()) > + return ERR_PTR(-ENOENT); > + > pr_debug("creating file '%s'\n", name); > > if (IS_ERR(parent)) That works. -michael