Messages in this thread Patch in this message |  | | From | Jiri Slaby <> | Subject | [PATCH 3.12 117/122] parport: parport_pc, do not remove parent devices early | Date | Tue, 17 Feb 2015 12:35:04 +0100 |
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3.12-stable review patch. If anyone has any objections, please let me know.
===============
commit 91905b6f4afe51e23a3f58df93e4cdc5e49cf40c upstream.
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: ... [<ffffffff810aff76>] warn_slowpath_fmt+0x46/0x50 [<ffffffff8123d81b>] sysfs_remove_group+0x9b/0xa0 [<ffffffff814c27e7>] dpm_sysfs_remove+0x57/0x60 [<ffffffff814b6ac9>] device_del+0x49/0x240 [<ffffffff814b6ce2>] device_unregister+0x22/0x70 [<ffffffff814b6dac>] device_destroy+0x3c/0x50 [<ffffffffc012209a>] pp_detach+0x4a/0x60 [ppdev] [<ffffffff814b32dd>] parport_remove_port+0x11d/0x150 [<ffffffffc0137328>] parport_pc_unregister_port+0x28/0xf0 [parport_pc] [<ffffffffc0138c0e>] parport_pc_exit+0x76/0x468 [parport_pc] [<ffffffff81128dbc>] 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 <jslaby@suse.cz> Reviewed-by: Takashi Iwai <tiwai@suse.de> Tested-by: Martin Pluskal <mpluskal@suse.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Jiri Slaby <jslaby@suse.cz> --- drivers/parport/parport_pc.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/drivers/parport/parport_pc.c b/drivers/parport/parport_pc.c index b0a0d5389f41..ae50d99883cf 100644 --- a/drivers/parport/parport_pc.c +++ b/drivers/parport/parport_pc.c @@ -3312,13 +3312,14 @@ 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)); } } -- 2.2.2
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