On Wed, Jun 19, 2024 at 04:28:29PM +0200, Marek Behún wrote:
> From: Pali Rohár <pali@xxxxxxxxxx>
>
> Documentation for irq_domain_remove() says that all mapping within the
> domain must be disposed prior to domain remove.
>
> Currently INTx irqs are not disposed in pci-mvebu.c device unbind callback
> which cause that kernel crashes after unloading driver and trying to read
> /sys/kernel/debug/irq/irqs/<num> or /proc/interrupts.
I was wondering why this is safe. Are there still users? If the users
are being removed first, why are there still mappings. This is
discussed in the old thread:
> I think that in this case for pci-mvebu.c it is safe because: At the
> first step of unbind procedure is called unregistraction of PCIe bus
> with all devices bound on it. This ensures that all PCIe endpoint
> drivers are unbind, devices removed and no new driver or device and
> appear. After that there should not be any remaining usage of PCIe
> resources (if there is then whole PCIe hotplug code is broken and we
> have other and bigger issue...). Next pci-mvebu.c manually disposes
> all remaining legacy interrupts (which PCI core code does not
> because legacy interrupts are shared and it does not know if they
> are used or not). This is safe because at these stage there are no
> PCI drivers bound, there is no PCI device for that controller
> registered. And after that is removed IRQ domain (which has finally
> disposed all interrupts).
If there is a need to respin, it would be good to include this in the
commit message.
Andrew
