On Wed, Mar 01, 2017 at 03:41:20PM -0600, Bjorn Helgaas wrote: > On Sat, Feb 25, 2017 at 11:53:13PM -0700, Logan Gunthorpe wrote: > > Changes since v4: > > > > * Turns out pushing the pci release code into the device release > > function didn't work as I would have liked. If you try to unbind the > > device with an instance open, then you hit a kernel bug at > > drivers/pci/msi.c:371. (This didn't occur in v3.) > > This is in free_msi_irqs(): > > 368 for_each_pci_msi_entry(entry, dev) > 369 if (entry->irq) > 370 for (i = 0; i < entry->nvec_used; i++) > 371 BUG_ON(irq_has_action(entry->irq + i)); > > I don't think this is indicating a bug in the PCI core (although I do > think a BUG_ON() here is an excessive response). I think it's an > indication that the driver didn't disconnect its ISR. Without more > details of the failure it's hard to tell if the BUG_ON is a symptom of > a problem in the driver or what. > > An "alive" flag feels racy, and I can't tell if it's really the best > way to deal with this, or if it's just avoiding the issue. There must > be other drivers with the same cleanup issue -- do they handle it the > same way? I think this is from using the managed device resource API to request the irq actions. The scope of the resource used to be tied to the pci_dev's dev, but now it's the new switchec class dev, which has a different lifetime while open references exist, so it's not releasing the irq's. One thing about the BUG_ON that is confusing me is how it's getting to free_msi_irq's BUG in v4 or v5. I don't see any part releasing the allocated ones. Maybe the devres API is harder to use than having the driver manage all the resources...
