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=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 09FB8C48BD1 for ; Thu, 10 Jun 2021 06:37:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DF93C613DE for ; Thu, 10 Jun 2021 06:37:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230106AbhFJGjc (ORCPT ); Thu, 10 Jun 2021 02:39:32 -0400 Received: from mail.kernel.org ([198.145.29.99]:35692 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229792AbhFJGjc (ORCPT ); Thu, 10 Jun 2021 02:39:32 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id A04A1613DF; Thu, 10 Jun 2021 06:37:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1623307055; bh=c6XuiGRrMxEn9EK3yNEORuo3dLeVk867t8/lnjEZuQ0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=hBjjoP/46sg3RECnjJ4l1ZbObZcyf7xKmtT/FZRlmp4DaS5KBSS1QL6JMqMYxfFLo 909MDbU0KdrKwRKtr1ADfFxetRJjKMdsIfHKsJS6h/qT+JuoponxL2Cbk0dxJ6gxp8 lXYybvpv3rieeQgdjub6P8eMeds1mGoTkFr9B7Ec= Date: Thu, 10 Jun 2021 08:36:57 +0200 From: Greg Kroah-Hartman To: Peter Chen Cc: balbi@kernel.org, Jack Pham , linux-usb@vger.kernel.org Subject: Re: [PATCH 1/1] usb: dwc3: core: fix kernel panic when do reboot Message-ID: References: <20210608105656.10795-1-peter.chen@kernel.org> <20210608164933.GA2601@jackp-linux.qualcomm.com> <20210610020047.GB6592@nchen> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210610020047.GB6592@nchen> Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org On Thu, Jun 10, 2021 at 10:00:47AM +0800, Peter Chen wrote: > On 21-06-09 11:42:53, Greg Kroah-Hartman wrote: > > On Wed, Jun 09, 2021 at 11:01:07AM +0200, Greg Kroah-Hartman wrote: > > > On Tue, Jun 08, 2021 at 09:50:01AM -0700, Jack Pham wrote: > > > > Hi Peter, > > > > > > > > On Tue, Jun 08, 2021 at 06:56:56PM +0800, Peter Chen wrote: > > > > > When do system reboot, it calls dwc3_shutdown and the whole debugfs > > > > > for dwc3 has removed first, when the gadget tries to do deinit, and > > > > > remove debugfs for its endpoints, it meets NULL pointer dereference > > > > > issue when call debugfs_lookup. Fix it by removing the whole dwc3 > > > > > debugfs later than dwc3_drd_exit. > > > > > > > > Ouch, thanks for catching this! I think in your previous reply[1] you > > > > did warn about the debugfs_remove_recursive() getting called twice, but > > > > it seems here the issue is due to the debugfs_lookup() getting called on > > > > a stale dwc->root pointer after it was already removed. > > > > > > We can also fix this by getting rid of that "root" pointer as it's > > > useless (we can look it up if we need it.) I'll send a patch later to > > > do that, as it's a good idea to do anyway, and is independant of this > > > fix. > > > > Now sent: > > https://lore.kernel.org/r/20210609093924.3293230-1-gregkh@linuxfoundation.org > > Hi Felipe, > > With Greg above patch, this issue is fixed indirectly. I don't think my patch is > needed, do you think so? Which patch is "your patch" here? thanks, greg k-h