On Mon, Sep 10, 2018 at 06:09:26PM +0200, Lukas Wunner wrote:
> On Mon, Sep 10, 2018 at 08:56:42AM -0600, Keith Busch wrote:
> > The sysfs entries still function. Their actions are only temporarily
> > stalled during error handling. Once the slot reset is called, the
> > ctrl->pending_events is queried to take requested actions.
>
> Okay I see. Still, releasing the IRQ and requesting it again seems fairly
> heavy-wheight. Why not just acquire ctrl->reset_lock?
That was looking like a nice way to handle it, but it introduces
circular locking between ctrl->reset_lock and pci_bus_sem:
CPU A CPU B
--------------------------------- ------------------------
pci_walk_bus pciehp_ist
down_read(&pci_bus_sem) down_read(&ctrl->reset_lock);
pcie_portdrv_error_detected pciehp_handle_presence_or_link_change
pciehp_error_detected pciehp_unconfigure_device
down_write(&ctrl->reset_lock) pci_stop_and_remove_bus_devicea
down_write(&pci_bus_sem);
