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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 59699C4332F for ; Fri, 3 Nov 2023 18:36:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230207AbjKCSgg (ORCPT ); Fri, 3 Nov 2023 14:36:36 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36300 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233951AbjKCSgf (ORCPT ); Fri, 3 Nov 2023 14:36:35 -0400 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AD2E9D47; Fri, 3 Nov 2023 11:36:29 -0700 (PDT) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C2D3DC433C9; Fri, 3 Nov 2023 18:36:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1699036589; bh=t9OfWxjmRBsqiXsPbyw2EcQvdxCl+LfcMDqz160D6P0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=VU/FOCJ/cTCilDbfiLeOP72tgqUIXdMSVGR+Ke5guOy/o/T/rbXj1FufplOpovd+w Itxd0lOZTAw1wvsRc9+8rylrt0HhsOmJY6QfDgh+OjdSGr6t4EBqGkhhDCqM8tmeme mDRNr1NzPYZtZ4Sg7B5sdiVLT0UnDsz90WxQ6vXs= Date: Fri, 3 Nov 2023 19:36:21 +0100 From: Greg KH To: =?iso-8859-1?Q?Jos=E9?= Pekkarinen Cc: rafael@kernel.org, len.brown@intel.com, pavel@ucw.cz, skhan@linuxfoundation.org, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kernel-mentees@lists.linuxfoundation.org, syzbot+95f2e2439b97575ec3c0@syzkaller.appspotmail.com Subject: Re: [PATCH] drivers core: lookup sysfs power group before removal Message-ID: <2023110353-bring-contented-c9f8@gregkh> References: <20231101173627.2658-1-jose.pekkarinen@foxhound.fi> <2023110139-dupe-snipping-5700@gregkh> <835b2930c710381b8da38eca821aa92d@foxhound.fi> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <835b2930c710381b8da38eca821aa92d@foxhound.fi> Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org On Fri, Nov 03, 2023 at 07:49:39PM +0200, José Pekkarinen wrote: > On 2023-11-01 19:54, Greg KH wrote: > > On Wed, Nov 01, 2023 at 07:36:27PM +0200, José Pekkarinen wrote: > > > Hinted by syzboot, there is a few cases where the sysfs power group > > > may > > > not be there, like the failure while adding it, or adding its runtime > > > group, or when the sysfs firmware loader fallback fail to populate. In > > > the last case, the device_del function will be called leading to > > > attempt > > > to remove the sysfs group. This patch will lookup for it in advance to > > > grant that it is effectively there before cleaning it up. > > > > > > Reported-by: syzbot+95f2e2439b97575ec3c0@syzkaller.appspotmail.com > > > > > > Signed-off-by: José Pekkarinen > > > --- > > > drivers/base/power/sysfs.c | 4 +++- > > > 1 file changed, 3 insertions(+), 1 deletion(-) > > > > > > diff --git a/drivers/base/power/sysfs.c b/drivers/base/power/sysfs.c > > > index a1474fb67db9..6601729c4698 100644 > > > --- a/drivers/base/power/sysfs.c > > > +++ b/drivers/base/power/sysfs.c > > > @@ -834,5 +834,7 @@ void dpm_sysfs_remove(struct device *dev) > > > dev_pm_qos_constraints_destroy(dev); > > > rpm_sysfs_remove(dev); > > > sysfs_unmerge_group(&dev->kobj, &pm_wakeup_attr_group); > > > - sysfs_remove_group(&dev->kobj, &pm_attr_group); > > > + > > > + if (kernfs_find_and_get((&dev->kobj)->sd, pm_attr_group.name)) > > > + sysfs_remove_group(&dev->kobj, &pm_attr_group); > > > > What's to keep it from going away right after finding it? > > > > In other words, what is wrong with removing a group that is not there? > > What error happens? It should be fine, or are you seeing real code > > failures somewhere? > > No, this is just hitting a warning that sysbot complains about by > setting panic on warning, no big deal, though it can be a wrong behaviour > in ueagle-atm driver, since it defines to disconnect the device if the > firmware is not there, no matter the sysfs fallback. Then fix the driver please. And what warning are you seeing exactly? thanks, greg k-h