From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752688Ab3KSNQC (ORCPT ); Tue, 19 Nov 2013 08:16:02 -0500 Received: from v094114.home.net.pl ([79.96.170.134]:61973 "HELO v094114.home.net.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1752611Ab3KSNP7 (ORCPT ); Tue, 19 Nov 2013 08:15:59 -0500 From: "Rafael J. Wysocki" To: Mika Westerberg , Greg Kroah-Hartman Cc: linux-kernel@vger.kernel.org, Tejun Heo Subject: Re: [PATCH] sysfs: handle duplicate removal attempts in sysfs_remove_group() Date: Tue, 19 Nov 2013 14:28:37 +0100 Message-ID: <1860373.lFaAX58EHT@vostro.rjw.lan> User-Agent: KMail/4.10.5 (Linux/3.12.0-rc6+; KDE/4.10.5; x86_64; ; ) In-Reply-To: <1384866598-19716-1-git-send-email-mika.westerberg@linux.intel.com> References: <1384866598-19716-1-git-send-email-mika.westerberg@linux.intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="utf-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tuesday, November 19, 2013 03:09:58 PM Mika Westerberg wrote: > Commit bcdde7e221a8 (sysfs: make __sysfs_remove_dir() recursive) changed > the behavior so that directory removals will be done recursively. This > means that the sysfs group might already be removed if its parent directory > has been removed. > > The current code outputs warnings similar to following log snippet when it > detects that there is no group for the given kobject: > > WARNING: CPU: 0 PID: 4 at fs/sysfs/group.c:214 sysfs_remove_group+0xc6/0xd0() > sysfs group ffffffff81c6f1e0 not found for kobject 'host7' > Modules linked in: > CPU: 0 PID: 4 Comm: kworker/0:0 Not tainted 3.12.0+ #13 > Hardware name: /D33217CK, BIOS GKPPT10H.86A.0042.2013.0422.1439 04/22/2013 > Workqueue: kacpi_hotplug acpi_hotplug_work_fn > 0000000000000009 ffff8801002459b0 ffffffff817daab1 ffff8801002459f8 > ffff8801002459e8 ffffffff810436b8 0000000000000000 ffffffff81c6f1e0 > ffff88006d440358 ffff88006d440188 ffff88006e8b4c28 ffff880100245a48 > Call Trace: > [] dump_stack+0x45/0x56 > [] warn_slowpath_common+0x78/0xa0 > [] warn_slowpath_fmt+0x47/0x50 > [] ? sysfs_get_dirent_ns+0x49/0x70 > [] sysfs_remove_group+0xc6/0xd0 > [] dpm_sysfs_remove+0x3e/0x50 > [] device_del+0x40/0x1b0 > [] device_unregister+0xd/0x20 > [] scsi_remove_host+0xba/0x110 > [] ata_host_detach+0xc6/0x100 > [] ata_pci_remove_one+0x18/0x20 > [] pci_device_remove+0x28/0x60 > [] __device_release_driver+0x64/0xd0 > [] device_release_driver+0x1e/0x30 > [] bus_remove_device+0xf7/0x140 > [] device_del+0x121/0x1b0 > [] pci_stop_bus_device+0x94/0xa0 > [] pci_stop_bus_device+0x3b/0xa0 > [] pci_stop_bus_device+0x3b/0xa0 > [] pci_stop_and_remove_bus_device+0xd/0x20 > [] trim_stale_devices+0x73/0xe0 > [] trim_stale_devices+0xbb/0xe0 > [] trim_stale_devices+0xbb/0xe0 > [] acpiphp_check_bridge+0x7e/0xd0 > [] hotplug_event+0xcd/0x160 > [] hotplug_event_work+0x25/0x60 > [] acpi_hotplug_work_fn+0x17/0x22 > [] process_one_work+0x17a/0x430 > [] worker_thread+0x119/0x390 > [] ? manage_workers.isra.25+0x2a0/0x2a0 > [] kthread+0xcd/0xf0 > [] ? kthread_create_on_node+0x180/0x180 > [] ret_from_fork+0x7c/0xb0 > [] ? kthread_create_on_node+0x180/0x180 > > On this particular machine I see ~16 of these message during Thunderbolt > hot-unplug. > > Fix this in similar way that was done for sysfs_remove_one() by checking > if the parent directory has already been removed and bailing out early. > > Signed-off-by: Mika Westerberg > --- > I'm not 100% sure that this is the correct solution. It seem to fix my case > but I might be missing something as I'm not that familiar with sysfs. It's done analogously in sysfs_remove_one(), so this looks like a correct fix to me: Acked-by: Rafael J. Wysocki > > fs/sysfs/group.c | 9 +++++++++ > 1 file changed, 9 insertions(+) > > diff --git a/fs/sysfs/group.c b/fs/sysfs/group.c > index 1898a10e38ce..8951bfb4e567 100644 > --- a/fs/sysfs/group.c > +++ b/fs/sysfs/group.c > @@ -206,6 +206,15 @@ void sysfs_remove_group(struct kobject *kobj, > struct sysfs_dirent *dir_sd = kobj->sd; > struct sysfs_dirent *sd; > > + /* > + * Sysfs directories are now removed recursively by > + * sysfs_remove_dir(). This means that this function can be called > + * multiple times on the same group. If the parent directory is > + * already removed we don't do anything here. > + */ > + if (dir_sd->s_flags & SYSFS_FLAG_REMOVED) > + return; > + > if (grp->name) { > sd = sysfs_get_dirent(dir_sd, grp->name); > if (!sd) { > -- I speak only for myself. Rafael J. Wysocki, Intel Open Source Technology Center.