On Mon, Sep 23, 2019 at 11:12:42AM +0300, Mika Westerberg wrote: > Regarding suggestion of unbinding PCI drivers without > pci_lock_rescan_remove() hold, I haven't looked it too closely but I > think we need to take that lock anyway because when we are unbinding a > hotplug driver it is supposed to remove the hierarchy below touching the > shared structures, possibly concurrently. Unfortunately there is no > documentation what data pci_lock_rescan_remove() actually protects so > first one needs to understand that. I think one way to clean up this is > to use finer grained locking (with documented lock ordering) for PCI bus > structures that can be accessed simultaneusly by different threads. But > that is not a simple task. Now that I looked more closely, I realized it actually is not supposed to remove the hierarchy below so indeed it might be possible to do that without taking pci_lock_rescan_remove().
