rt2x00: prevent double kfree when failing to register hardware

In a scenario where there isn't any firmware available, we will have a
double kfree of rt2x00dev->spec.channels_info when ieee80211_register_hw
returns an error status inside rt2x00lib_probe_hw.

The problem is that if ieee80211_register_hw fails, we call
rt2x00lib_remove_hw twice:
* first inside rt2x00lib_probe_hw upon failure of ieee80211_register_hw
* error status is returned to rt2x00lib_probe_dev, which then sees it and
  calls in this case rt2x00lib_remove_dev that will again run
  rt2x00lib_remove_hw

Prevent this avoiding calling rt2x00lib_remove_hw inside
rt2x00lib_probe_hw

Problem was detected with CONFIG_DEBUG_PAGEALLOC=y, CONFIG_SLUB_DEBUG=y,
CONFIG_SLUB_DEBUG_ON=y, that dumps this with no firmware available:

rt61pci 0000:00:07.0: PCI INT A -> GSI 19 (level, low) -> IRQ 19
wmaster0 (rt61pci): not using net_device_ops yet
phy0: Selected rate control algorithm 'pid'
phy0: Failed to initialize wep: -2
phy0 -> rt2x00lib_probe_dev: Error - Failed to initialize hw.
=============================================================================
BUG kmalloc-128: Object already free
-----------------------------------------------------------------------------

INFO: Allocated in rt61pci_probe_hw+0x3e5/0x6e0 [rt61pci] age=340 cpu=0 pid=21
INFO: Freed in rt2x00lib_remove_hw+0x59/0x70 [rt2x00lib] age=0 cpu=0 pid=21
INFO: Slab 0xc13ac3e0 objects=23 used=10 fp=0xdd59f6e0 flags=0x400000c3
INFO: Object 0xdd59f6e0 @offset=1760 fp=0xdd59f790

Bytes b4 0xdd59f6d0:  15 00 00 00 b2 8a fb ff 5a 5a 5a 5a 5a 5a 5a 5a ....².ûÿZZZZZZZZ
  Object 0xdd59f6e0:  6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkkkkkkkkkkkkkk
  Object 0xdd59f6f0:  6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkkkkkkkkkkkkkk
  Object 0xdd59f700:  6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkkkkkkkkkkkkkk
  Object 0xdd59f710:  6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkkkkkkkkkkkkkk
  Object 0xdd59f720:  6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkkkkkkkkkkkkkk
  Object 0xdd59f730:  6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkkkkkkkkkkkkkk
  Object 0xdd59f740:  6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkkkkkkkkkkkkkk
  Object 0xdd59f750:  6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b a5 kkkkkkkkkkkkkkk¥
 Redzone 0xdd59f760:  bb bb bb bb                                     »»»»
 Padding 0xdd59f788:  5a 5a 5a 5a 5a 5a 5a 5a                         ZZZZZZZZ
Pid: 21, comm: stage1 Not tainted 2.6.29.1-desktop-1.1mnb #1
Call Trace:
 [<c01abbb3>] print_trailer+0xd3/0x120
 [<c01abd37>] object_err+0x37/0x50
 [<c01acf57>] __slab_free+0xe7/0x2f0
 [<c01ad1de>] kfree+0x7e/0xd0
 [<e0e4a239>] ? rt2x00lib_remove_hw+0x59/0x70 [rt2x00lib]
 [<e0e4a239>] ? rt2x00lib_remove_hw+0x59/0x70 [rt2x00lib]
 [<e0e4a239>] rt2x00lib_remove_hw+0x59/0x70 [rt2x00lib]
 [<e0e4acc7>] rt2x00lib_remove_dev+0x37/0x50 [rt2x00lib]
 [<e0e4b087>] rt2x00lib_probe_dev+0x1a7/0x3b0 [rt2x00lib]
 [<e0eb288f>] rt2x00pci_probe+0xdf/0x1ee [rt2x00pci]
 [<c026b9ee>] local_pci_probe+0xe/0x10
 [<c026c750>] pci_device_probe+0x60/0x80
 [<c02d5c2a>] driver_probe_device+0x9a/0x2e0
 [<c02d5ef9>] __driver_attach+0x89/0x90
 [<c02d541b>] bus_for_each_dev+0x4b/0x70
 [<c026c690>] ? pci_device_remove+0x0/0x40
 [<c02d59d9>] driver_attach+0x19/0x20
 [<c02d5e70>] ? __driver_attach+0x0/0x90
 [<c02d4cef>] bus_add_driver+0x1cf/0x2a0
 [<c026c690>] ? pci_device_remove+0x0/0x40
 [<c02d60c9>] driver_register+0x69/0x140
 [<c026c9b0>] __pci_register_driver+0x40/0x80
 [<e0ecc000>] ? rt61pci_init+0x0/0x19 [rt61pci]
 [<e0ecc017>] rt61pci_init+0x17/0x19 [rt61pci]
 [<c0101116>] do_one_initcall+0x26/0x1c0
 [<c01ab90c>] ? slab_pad_check+0x3c/0x120
 [<c01ab90c>] ? slab_pad_check+0x3c/0x120
 [<c01ac8da>] ? check_object+0xda/0x210
 [<c01b0026>] ? percpu_free+0x46/0x50
 [<c01ad09e>] ? __slab_free+0x22e/0x2f0
 [<c01b0026>] ? percpu_free+0x46/0x50
 [<c01b0026>] ? percpu_free+0x46/0x50
 [<c01b0026>] ? percpu_free+0x46/0x50
 [<c01687ec>] ? stop_machine_destroy+0x3c/0x40
 [<c015e515>] ? load_module+0xa5/0x1c50
 [<e0ec5000>] ? rt61pci_eepromregister_read+0x0/0x40 [rt61pci]
 [<e0eb2000>] ? rt2x00pci_write_tx_data+0x0/0x90 [rt2x00pci]
 [<c03ac2fb>] ? mutex_lock+0xb/0x20
 [<c03ac2fb>] ? mutex_lock+0xb/0x20
 [<c017ad16>] ? tracepoint_update_probe_range+0x76/0xa0
 [<c017ad6f>] ? tracepoint_module_notify+0x2f/0x40
 [<c03b02ed>] ? notifier_call_chain+0x2d/0x70
 [<c014f0ed>] ? __blocking_notifier_call_chain+0x4d/0x60
 [<c014f11a>] ? blocking_notifier_call_chain+0x1a/0x20
 [<c0160156>] sys_init_module+0x96/0x1d0
 [<c019dad6>] ? sys_munmap+0x46/0x60
 [<c0105546>] syscall_call+0x7/0xb
FIX kmalloc-128: Object at 0xdd59f6e0 not freed
rt61pci 0000:00:07.0: PCI INT A disabled
rt61pci: probe of 0000:00:07.0 failed with error -2
Signed-off-by: NHerton Ronaldo Krzesinski <herton@mandriva.com.br>
Acked-by: NIvo van Doorn <IvDoorn@gmail.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

drivers/net/wireless/rt2x00/rt2x00dev.c

@@ -646,10 +646,8 @@ static int rt2x00lib_probe_hw(struct rt2x00_dev *rt2x00dev)
 	 * Register HW.
 	 */
 	status = ieee80211_register_hw(rt2x00dev->hw);
-	if (status) {
-		rt2x00lib_remove_hw(rt2x00dev);
+	if (status)
 		return status;
-	}
 
 	set_bit(DEVICE_STATE_REGISTERED_HW, &rt2x00dev->flags);