igb: clean up in all error paths when enabling SR-IOV

After commit 50f30349 ("igb: Enable SR-IOV after reinit"), removing
the igb module could hang or crash (depending on the machine) when the
module has been loaded with the max_vfs parameter set to some value != 0.

In case of one test machine with a dual port 82580, this hang occurred:

[  232.480687] igb 0000:41:00.1: removed PHC on enp65s0f1
[  233.093257] igb 0000:41:00.1: IOV Disabled
[  233.329969] pcieport 0000:40:01.0: AER: Multiple Uncorrected (Non-Fatal) err0
[  233.340302] igb 0000:41:00.0: PCIe Bus Error: severity=Uncorrected (Non-Fata)
[  233.352248] igb 0000:41:00.0:   device [8086:1516] error status/mask=00100000
[  233.361088] igb 0000:41:00.0:    [20] UnsupReq               (First)
[  233.368183] igb 0000:41:00.0: AER:   TLP Header: 40000001 0000040f cdbfc00c c
[  233.376846] igb 0000:41:00.1: PCIe Bus Error: severity=Uncorrected (Non-Fata)
[  233.388779] igb 0000:41:00.1:   device [8086:1516] error status/mask=00100000
[  233.397629] igb 0000:41:00.1:    [20] UnsupReq               (First)
[  233.404736] igb 0000:41:00.1: AER:   TLP Header: 40000001 0000040f cdbfc00c c
[  233.538214] pci 0000:41:00.1: AER: can't recover (no error_detected callback)
[  233.538401] igb 0000:41:00.0: removed PHC on enp65s0f0
[  233.546197] pcieport 0000:40:01.0: AER: device recovery failed
[  234.157244] igb 0000:41:00.0: IOV Disabled
[  371.619705] INFO: task irq/35-aerdrv:257 blocked for more than 122 seconds.
[  371.627489]       Not tainted 6.4.0-dirty #2
[  371.632257] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this.
[  371.641000] task:irq/35-aerdrv   state:D stack:0     pid:257   ppid:2      f0
[  371.650330] Call Trace:
[  371.653061]  <TASK>
[  371.655407]  __schedule+0x20e/0x660
[  371.659313]  schedule+0x5a/0xd0
[  371.662824]  schedule_preempt_disabled+0x11/0x20
[  371.667983]  __mutex_lock.constprop.0+0x372/0x6c0
[  371.673237]  ? __pfx_aer_root_reset+0x10/0x10
[  371.678105]  report_error_detected+0x25/0x1c0
[  371.682974]  ? __pfx_report_normal_detected+0x10/0x10
[  371.688618]  pci_walk_bus+0x72/0x90
[  371.692519]  pcie_do_recovery+0xb2/0x330
[  371.696899]  aer_process_err_devices+0x117/0x170
[  371.702055]  aer_isr+0x1c0/0x1e0
[  371.705661]  ? __set_cpus_allowed_ptr+0x54/0xa0
[  371.710723]  ? __pfx_irq_thread_fn+0x10/0x10
[  371.715496]  irq_thread_fn+0x20/0x60
[  371.719491]  irq_thread+0xe6/0x1b0
[  371.723291]  ? __pfx_irq_thread_dtor+0x10/0x10
[  371.728255]  ? __pfx_irq_thread+0x10/0x10
[  371.732731]  kthread+0xe2/0x110
[  371.736243]  ? __pfx_kthread+0x10/0x10
[  371.740430]  ret_from_fork+0x2c/0x50
[  371.744428]  </TASK>

The reproducer was a simple script:

  #!/bin/sh
  for i in `seq 1 5`; do
    modprobe -rv igb
    modprobe -v igb max_vfs=1
    sleep 1
    modprobe -rv igb
  done

It turned out that this could only be reproduce on 82580 (quad and
dual-port), but not on 82576, i350 and i210.  Further debugging showed
that igb_enable_sriov()'s call to pci_enable_sriov() is failing, because
dev->is_physfn is 0 on 82580.

Prior to commit 50f30349 ("igb: Enable SR-IOV after reinit"),
igb_enable_sriov() jumped into the "err_out" cleanup branch.  After this
commit it only returned the error code.

So the cleanup didn't take place, and the incorrect VF setup in the
igb_adapter structure fooled the igb driver into assuming that VFs have
been set up where no VF actually existed.

Fix this problem by cleaning up again if pci_enable_sriov() fails.

Fixes: 50f30349 ("igb: Enable SR-IOV after reinit")
Signed-off-by: Corinna Vinschen <vinschen@redhat.com>
Reviewed-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Tested-by: Rafal Romanowski <rafal.romanowski@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>