RE: [PATCH net-next v8 6/9] net: txgbe: Support GPIO to SFP socket

["Jiawen Wu" <jiawenwu@trustnetic.com>]

> > > > If you are getting errors when removing the driver it means you are
> > > > missing some level of undoing what us done in probe. Are you sure
> > > > regmap_del_irq_chip() is being called on unload?
> > >
> > > I used devm_* all when I registered them.
> >
> > Look at the ordering. Is regmap_del_irq_chip() being called too late?
> > I've had problems like this with the mv88e6xxx driver and its
> > interrupt controllers. I ended up not using devm_ so i had full
> > control over the order things got undone. In that case, the external
> > devices was PHYs, with the PHY interrupt being inside the Ethernet
> > switch, which i exposed using a Linux interrupt controller.
> 
> I use no devm_ functions to add regmap irq chip, register gpio regmap,
> and call their del/unregister functions at the position corresponding to
> release. irq_domain_remove() call trace still exist.
> 
> [  104.553182] Call Trace:
> [  104.553184]  <TASK>
> [  104.553185]  irq_domain_remove+0x2b/0xe0
> [  104.553190]  regmap_del_irq_chip.part.0+0x8a/0x160
> [  104.553196]  txgbe_remove_phy+0x57/0x80 [txgbe]
> [  104.553201]  txgbe_remove+0x2a/0x90 [txgbe]
> [  104.553205]  pci_device_remove+0x36/0xa0
> [  104.553208]  device_release_driver_internal+0xaa/0x140
> [  104.553213]  driver_detach+0x44/0x90
> [  104.553215]  bus_remove_driver+0x69/0xf0
> [  104.553217]  pci_unregister_driver+0x29/0xb0
> [  104.553220]  __x64_sys_delete_module+0x145/0x240
> [  104.553223]  ? exit_to_user_mode_prepare+0x3c/0x1a0
> [  104.553226]  do_syscall_64+0x3b/0x90
> [  104.553230]  entry_SYSCALL_64_after_hwframe+0x72/0xdc

I think this problem is caused by a conflict calling of irq_domain_remove()
between the two functions gpiochip_irqchip_remove() and regmap_del_irq_chip().
The front one is called by gpio_regmap_unregister().

I adjusted the order of release functions, regmap_del_irq_chip() first, then
gpio_regmap_unregister(). Log became:

[  383.261168] Call Trace:
[  383.261169]  <TASK>
[  383.261170]  irq_domain_remove+0x2b/0xe0
[  383.261174]  gpiochip_irqchip_remove+0xf0/0x210
[  383.261177]  gpiochip_remove+0x4a/0x110
[  383.261181]  gpio_regmap_unregister+0x12/0x20 [gpio_regmap]
[  383.261186]  txgbe_remove_phy+0x57/0x80 [txgbe]
[  383.261190]  txgbe_remove+0x2a/0x90 [txgbe]

irq_domain_remove() just free the memory of irq_domain, but its pointer address
still exists. So it will be called twice.