From 91905b6f4afe51e23a3f58df93e4cdc5e49cf40c Mon Sep 17 00:00:00 2001 From: Jiri Slaby Date: Fri, 21 Nov 2014 10:05:09 +0100 Subject: parport: parport_pc, do not remove parent devices early When the parport_pc module is removed from the system, all parport devices are iterated in parport_pc_exit and removed by a call to parport_pc_unregister_port. Note that some parport devices have its 'struct device' parent, known as port->dev. And when port->dev is a platform device, it is destroyed in parport_pc_exit too. Now, when parport_pc_unregister_port is called for a going port, drv->detach(port) is called for every parport driver in the system. ppdev can be one of them. ppdev's detach() tears down its per-port sysfs directory, which established port->dev as a parent earlier. But since parport_pc_exit kills port->dev parents before unregisters ports proper, ppdev's sysfs directory has no living parent anymore. This results in the following warning: WARNING: CPU: 1 PID: 785 at fs/sysfs/group.c:219 sysfs_remove_group+0x9b/0xa0 sysfs group ffffffff81c69e20 not found for kobject 'parport1' Modules linked in: parport_pc(E-) ppdev(E) [last unloaded: ppdev] CPU: 1 PID: 785 Comm: rmmod Tainted: G W E 3.18.0-rc5-next-20141120+ #824 ... Call Trace: ... [] warn_slowpath_fmt+0x46/0x50 [] sysfs_remove_group+0x9b/0xa0 [] dpm_sysfs_remove+0x57/0x60 [] device_del+0x49/0x240 [] device_unregister+0x22/0x70 [] device_destroy+0x3c/0x50 [] pp_detach+0x4a/0x60 [ppdev] [] parport_remove_port+0x11d/0x150 [] parport_pc_unregister_port+0x28/0xf0 [parport_pc] [] parport_pc_exit+0x76/0x468 [parport_pc] [] SyS_delete_module+0x18c/0x230 It is also easily reproducible on qemu with two dummy ports '-parallel /dev/null -parallel /dev/null'. So switch the order of killing the two structures. But since port is freed by parport_pc_unregister_port, we have to remember port->dev in a local variable. Perhaps nothing worse than the warning happens thanks to the device refcounting. We *should* be on the safe side. Signed-off-by: Jiri Slaby Reviewed-by: Takashi Iwai Tested-by: Martin Pluskal Signed-off-by: Greg Kroah-Hartman --- drivers/parport/parport_pc.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) (limited to 'drivers/parport') diff --git a/drivers/parport/parport_pc.c b/drivers/parport/parport_pc.c index f721299eb1ba..5306eb537d10 100644 --- a/drivers/parport/parport_pc.c +++ b/drivers/parport/parport_pc.c @@ -3340,13 +3340,14 @@ static void __exit parport_pc_exit(void) while (!list_empty(&ports_list)) { struct parport_pc_private *priv; struct parport *port; + struct device *dev; priv = list_entry(ports_list.next, struct parport_pc_private, list); port = priv->port; - if (port->dev && port->dev->bus == &platform_bus_type) - platform_device_unregister( - to_platform_device(port->dev)); + dev = port->dev; parport_pc_unregister_port(port); + if (dev && dev->bus == &platform_bus_type) + platform_device_unregister(to_platform_device(dev)); } } -- cgit v1.2.3-58-ga151