The stub driver expects to access the usb interface
and usb device structures even if the device has been
disconnected in the meantime.

This change gets a reference to them in the stub probe
function using usb_get_intf()/usb_get_dev() and drops them
in the disconnect function.

This fixes an oops observed with a Logic Controls Line
display (0fa8:a030) which disconnects itself when it is
reset:

[ 1348.562274] BUG: unable to handle kernel paging request at 5f7433e5
[ 1348.562327] IP: [<c0393b02>] usb_lock_device_for_reset+0x22/0xd0
[ 1348.562374] *pde = 00000000
[ 1348.562397] Oops: 0000 [#1]
[ 1348.562418] last sysfs file: /sys/devices/pci0000:00/0000:00:10.2/usb4/4-1/bConfigurationValue
[ 1348.562454] Modules linked in: usbip vhci_hcd usbip_common_mod fbcon tileblit font bitblit softcursor serio_raw uvesafb pcspkr via_rng snd_via82xx gameport snd_ac97_codec ac97_bus snd_pcm_oss snd_mixer_oss snd_pcm snd_page_alloc snd_mpu401_uart snd_rawmidi snd_seq_oss snd_seq_midi_event snd_seq snd_timer snd_seq_device snd usbhid hid via_rhine soundcore mii igel_flash aufs pata_via
[ 1348.562649]
[ 1348.562670] Pid: 2855, comm: usbip_eh Not tainted (2.6.32 #23.37-ud-r113) M300C
[ 1348.562704] EIP: 0060:[<c0393b02>] EFLAGS: 00010216 CPU: 0
[ 1348.562734] EIP is at usb_lock_device_for_reset+0x22/0xd0
[ 1348.562762] EAX: 5f7433cd EBX: 5f7433cd ECX: de293a5c EDX: dd326a00
[ 1348.562793] ESI: 5f7433cd EDI: 000400f6 EBP: cf43ff48 ESP: cf43ff38
[ 1348.562824]  DS: 007b ES: 007b FS: 0000 GS: 00e0 SS: 0068
[ 1348.562854] Process usbip_eh (pid: 2855, ti=cf43e000 task=d2c7f230 task.ti=cf43e000)
[ 1348.562884] Stack:
[ 1348.562900]  d6ec9960 de2939cc 5f7433cd 5f743431 cf43ff70 df8fd32f de2939cc d2c7f230
[ 1348.562940] <0> cf43ff70 00000282 00000282 de2939cc d2c7f230 d2c7f230 cf43ffa8 df84416d
[ 1348.562987] <0> cf43ff88 d2c7f230 de293a24 d2c7f230 00000000 d2c7f230 c014e760 cf43ff94
[ 1348.563042] Call Trace:
[ 1348.563073]  [<df8fd32f>] ? stub_device_reset+0x3f/0x110 [usbip]
[ 1348.563114]  [<df84416d>] ? event_handler_loop+0xcd/0xe8 [usbip_common_mod]
[ 1348.563156]  [<c014e760>] ? autoremove_wake_function+0x0/0x50
[ 1348.563193]  [<df843d80>] ? usbip_thread+0x0/0x60 [usbip_common_mod]
[ 1348.563230]  [<df843dd1>] ? usbip_thread+0x51/0x60 [usbip_common_mod]
[ 1348.563265]  [<c014e374>] ? kthread+0x74/0x80
[ 1348.563294]  [<c014e300>] ? kthread+0x0/0x80
[ 1348.563326]  [<c0103c47>] ? kernel_thread_helper+0x7/0x10
[ 1348.563351] Code: 00 e8 73 4d 00 00 5d c3 90 55 89 e5 83 ec 10 89 5d f4 89 75 f8 89 7d fc 0f 1f 44 00 00 8b 3d c0 2e 67 c0 81 c7 fa 00 00 00 89 c3 <8b> 40 18 89 d6 85 c0 75 15 b8 ed ff ff ff 8b 5d f4 8b 75 f8 8b
[ 1348.563528] EIP: [<c0393b02>] usb_lock_device_for_reset+0x22/0xd0 SS:ESP 0068:cf43ff38
[ 1348.563570] CR2: 000000005f7433e5
[ 1348.563593] ---[ end trace 9c3f1e3a2e5299d9 ]---
Signed-off-by: Max Vozeler <max@vozeler.com>
Tested-by: Mark Wehby <MWehby@luxotticaRetail.com>
Tested-by: Steven Harms <sharms@luxotticaRetail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>