Re: [PATCH V5 3/3] PCI: Mask and unmask hotplug interrupts during reset
From: Lukas Wunner
Date: Tue Jul 03 2018 - 04:34:57 EST
On Mon, Jul 02, 2018 at 06:52:47PM -0400, Sinan Kaya wrote:
> If a bridge supports hotplug and observes a PCIe fatal error, the following
> events happen:
> 1. AER driver removes the devices from PCI tree on fatal error
> 2. AER driver brings down the link by issuing a secondary bus reset waits
> for the link to come up.
> 3. Hotplug driver observes a link down interrupt
> 4. Hotplug driver tries to remove the devices waiting for the rescan lock
> but devices are already removed by the AER driver and AER driver is waiting
> for the link to come back up.
> 5. AER driver tries to re-enumerate devices after polling for the link
> state to go up.
> 6. Hotplug driver obtains the lock and tries to remove the devices again.
> If a bridge is a hotplug capable bridge, mask hotplug interrupts before the
> reset and unmask afterwards.
Would it work for you if you just amended the AER driver to skip
removal and re-enumeration of devices if the port is a hotplug bridge?
Just check for is_hotplug_bridge in struct pci_dev.
That would seem like a much simpler solution, given that it is known
that the link will flap on reset, causing the hotplug driver to remove
and re-enumerate devices. That would also cover cases where hotplug is
handled by a different driver than pciehp, or by the platform firmware.