iavf: fix hang on reboot with ice

When a system with E810 with existing VFs gets rebooted the following
hang may be observed.

 Pid 1 is hung in iavf_remove(), part of a network driver:
 PID: 1        TASK: ffff965400e5a340  CPU: 24   COMMAND: "systemd-shutdow"
  #0 [ffffaad04005fa50] __schedule at ffffffff8b3239cb
  Freescale#1 [ffffaad04005fae8] schedule at ffffffff8b323e2d
  Freescale#2 [ffffaad04005fb00] schedule_hrtimeout_range_clock at ffffffff8b32cebc
  Freescale#3 [ffffaad04005fb80] usleep_range_state at ffffffff8b32c930
  Freescale#4 [ffffaad04005fbb0] iavf_remove at ffffffffc12b9b4c [iavf]
  Freescale#5 [ffffaad04005fbf0] pci_device_remove at ffffffff8add7513
  Freescale#6 [ffffaad04005fc10] device_release_driver_internal at ffffffff8af08baa
  Freescale#7 [ffffaad04005fc40] pci_stop_bus_device at ffffffff8adcc5fc
  Freescale#8 [ffffaad04005fc60] pci_stop_and_remove_bus_device at ffffffff8adcc81e
  Freescale#9 [ffffaad04005fc70] pci_iov_remove_virtfn at ffffffff8adf9429
 Freescale#10 [ffffaad04005fca8] sriov_disable at ffffffff8adf98e4
 Freescale#11 [ffffaad04005fcc8] ice_free_vfs at ffffffffc04bb2c8 [ice]
 Freescale#12 [ffffaad04005fd10] ice_remove at ffffffffc04778fe [ice]
 Freescale#13 [ffffaad04005fd38] ice_shutdown at ffffffffc0477946 [ice]
 Freescale#14 [ffffaad04005fd50] pci_device_shutdown at ffffffff8add58f1
 Freescale#15 [ffffaad04005fd70] device_shutdown at ffffffff8af05386
 Freescale#16 [ffffaad04005fd98] kernel_restart at ffffffff8a92a870
 Freescale#17 [ffffaad04005fda8] __do_sys_reboot at ffffffff8a92abd6
 Freescale#18 [ffffaad04005fee0] do_syscall_64 at ffffffff8b317159
 Freescale#19 [ffffaad04005ff08] __context_tracking_enter at ffffffff8b31b6fc
 Freescale#20 [ffffaad04005ff18] syscall_exit_to_user_mode at ffffffff8b31b50d
 Freescale#21 [ffffaad04005ff28] do_syscall_64 at ffffffff8b317169
 Freescale#22 [ffffaad04005ff50] entry_SYSCALL_64_after_hwframe at ffffffff8b40009b
     RIP: 00007f1baa5c13d7  RSP: 00007fffbcc55a98  RFLAGS: 00000202
     RAX: ffffffffffffffda  RBX: 0000000000000000  RCX: 00007f1baa5c13d7
     RDX: 0000000001234567  RSI: 0000000028121969  RDI: 00000000fee1dead
     RBP: 00007fffbcc55ca0   R8: 0000000000000000   R9: 00007fffbcc54e90
     R10: 00007fffbcc55050  R11: 0000000000000202  R12: 0000000000000005
     R13: 0000000000000000  R14: 00007fffbcc55af0  R15: 0000000000000000
     ORIG_RAX: 00000000000000a9  CS: 0033  SS: 002b

During reboot all drivers PM shutdown callbacks are invoked.
In iavf_shutdown() the adapter state is changed to __IAVF_REMOVE.
In ice_shutdown() the call chain above is executed, which at some point
calls iavf_remove(). However iavf_remove() expects the VF to be in one
of the states __IAVF_RUNNING, __IAVF_DOWN or __IAVF_INIT_FAILED. If
that's not the case it sleeps forever.
So if iavf_shutdown() gets invoked before iavf_remove() the system will
hang indefinitely because the adapter is already in state __IAVF_REMOVE.

Fix this by returning from iavf_remove() if the state is __IAVF_REMOVE,
as we already went through iavf_shutdown().

Fixes: 9745780 ("iavf: Add waiting so the port is initialized in remove")
Fixes: a841733 ("iavf: Fix race condition between iavf_shutdown and iavf_remove")
Reported-by: Marius Cornea <mcornea@redhat.com>
Signed-off-by: Stefan Assmann <sassmann@kpanic.de>
Reviewed-by: Michal Kubiak <michal.kubiak@intel.com>
Tested-by: Rafal Romanowski <rafal.romanowski@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

drivers/net/ethernet/intel/iavf/iavf_main.c

@@ -5074,6 +5074,11 @@ static void iavf_remove(struct pci_dev *pdev)
 			mutex_unlock(&adapter->crit_lock);
 			break;
 		}
+		/* Simply return if we already went through iavf_shutdown */
+		if (adapter->state == __IAVF_REMOVE) {
+			mutex_unlock(&adapter->crit_lock);
+			return;
+		}
 
 		mutex_unlock(&adapter->crit_lock);
 		usleep_range(500, 1000);