From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mark Langsdorf Subject: Re: [PATCH] phylib: fix device deletion order in mdiobus_unregister() Date: Tue, 01 Sep 2015 09:07:12 -0500 Message-ID: <55E5B110.5080704@redhat.com> References: <1441114565-2340-1-git-send-email-msalter@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Cc: David Daney , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, f.fainelli@gmail.com, buytenh@wantstofly.org, grant.likely@secretlab.ca To: Mark Salter , David Miller Return-path: In-Reply-To: <1441114565-2340-1-git-send-email-msalter@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On 09/01/2015 08:36 AM, Mark Salter wrote: > commit 8b63ec1837fa ("phylib: Make PHYs children of their MDIO bus, not > the bus' parent.") uncovered a problem in mdiobus_unregister() which > leads to this warning when I reboot an APM Mustang (arm64) platform: > > WARNING: CPU: 7 PID: 4239 at fs/sysfs/group.c:224 sysfs_remove_group+0xa0/0xa4() > sysfs group fffffe0000e07a10 not found for kobject 'xgene-mii-eth0:03' > ... > CPU: 7 PID: 4239 Comm: reboot Tainted: G E 4.2.0-0.18.el7.test15.aarch64 #1 > Hardware name: AppliedMicro Mustang/Mustang, BIOS 1.1.0 Aug 26 2015 > Call Trace: > [] dump_backtrace+0x0/0x170 > [] show_stack+0x20/0x2c > [] dump_stack+0x78/0x9c > [] warn_slowpath_common+0xa0/0xd8 > [] warn_slowpath_fmt+0x74/0x88 > [] sysfs_remove_group+0x9c/0xa4 > [] dpm_sysfs_remove+0x5c/0x70 > [] device_del+0x44/0x208 > [] device_unregister+0x2c/0x7c > [] mdiobus_unregister+0x48/0x94 > [] xgene_enet_mdio_remove+0x28/0x44 > [] xgene_enet_remove+0xd0/0xd8 > [] xgene_enet_shutdown+0x2c/0x3c > [] platform_drv_shutdown+0x24/0x40 > [] device_shutdown+0xf0/0x1b4 > [] kernel_restart_prepare+0x40/0x4c > [] kernel_restart+0x1c/0x80 > [] SyS_reboot+0x17c/0x250 > > The problem is that mdiobus_unregister() deletes the bus device before > unregistering the phy devices on the bus. This wasn't a problem before > because the phys were not children of the bus: > > /sys/devices/platform/APMC0D05:00/net/eth0/xgene-mii-eth0:03 > /sys/devices/platform/APMC0D05:00/net/eth0/xgene-mii-eth0 > > But now that they are: > > /sys/devices/platform/APMC0D05:00/net/eth0/xgene-mii-eth0/xgene-mii-eth0:03 > > when mdiobus_unregister deletes the bus device, the phy subdirs are > removed from sysfs also. So when the phys are unregistered afterward, > we get the warning. This patch changes the order so that phys are > unregistered before the bus device is deleted. > > Signed-off-by: Mark Salter > --- Tested-by: Mark Langsdorf