Kenji Kaneshige <kaneshige.kenji@xxxxxxxxxxxxxx> writes: > Eric W. Biederman wrote: >> ebiederm@xxxxxxxxxxxx (Eric W. Biederman) writes: >> >>> And on the big gotcha's I have found one more I am tracking. >>> >>> I am seeing pci bridges with a NULL pointer for the subordinate bus. >>> Earlier I had thought that this was a symptom of the double remove >>> but I have been able to reproduce it without that. >>> >>> On just a little bit deeper investigation it looks like the cases >>> are dying are all coming when the nested bridge reappears. >>> >>> Which is wrong on so many levels as I am toggle power to the outer >>> slot, so the nested bridge should not even exist at that time. Ugh. >>> More tracing to for me on that one. >> >> Ok. Got it. I was processing the interrupt for a device after it had >> been hot removed but before the device state had disappeared. >> >> pcie_isr looks like it would be even worse in that situation. Looping forever >> if pciehp_readw(ctrl, PCIE_EXPSLTA) always succeed sand returns 0xffff. >> >> That loop in there appears impossibly misguided. If the pending interrupt >> values change after you have received the interrupt another instance >> of the same interrupt should be pending so the loop should be completely >> unnecessary. >> > > For level-triggered interrupt, I think it's true. > > But for edge-triggered interrupt, I don't think it's true. I think > only one interrupt is generated if the first hotplug event occurs > and the second hotplug event occurs before clearing the status of > first hotplug event. My test case is edge-triggered MSI's. The issue is that I get an interrupt from the card that I am unplugging, but by the time the interrupt handler is executed the card is physically absent, but the pci_dev structure is still present in the kernel. Eric -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
