On Tue, May 21, 2013 at 05:30:32PM -0400, Don Dutile wrote: > On 05/14/2013 05:39 PM, Alexander Duyck wrote: > >On 05/14/2013 12:59 PM, Yinghai Lu wrote: > >>On Tue, May 14, 2013 at 12:45 PM, Alexander Duyck > >><alexander.h.duyck@xxxxxxxxx> wrote: > >>>On 05/14/2013 11:44 AM, Yinghai Lu wrote: > >>>>On Tue, May 14, 2013 at 9:00 AM, Alexander Duyck > >>>><alexander.h.duyck@xxxxxxxxx> wrote: > >>>>>I'm sorry, but what is the point of this patch? With device assignment > >>>>>it is always possible to have VFs loaded and the PF driver unloaded > >>>>>since you cannot remove the VFs if they are assigned to a VM. > >>>>unload PF driver will not call pci_disable_sriov? > >>>You cannot call pci_disable_sriov because you will panic all of the > >>>guests that have devices assigned. > >>ixgbe_remove did call pci_disable_sriov... > >> > >>for guest panic, that is another problem. > >>just like you pci passthrough with real pci device and hotremove the > >>card in host. > >> > >>... > > > >I suggest you take another look. In ixgbe_disable_sriov, which is the > >function that is called we do a check for assigned VFs. If they are > >assigned then we do not call pci_disable_sriov. > > > >> > >>>So how does your patch actually fix this problem? It seems like it is > >>>just avoiding it. > >>yes, until the first one is done. > > > >Avoiding the issue doesn't fix the underlying problem and instead you > >are likely just introducing more bugs as a result. > > > >>> From what I can tell your problem is originating in pci_call_probe. I > >>>believe it is calling work_on_cpu and that doesn't seem correct since > >>>the work should be taking place on a CPU already local to the PF. You > >>>might want to look there to see why you are trying to schedule work on a > >>>CPU which should be perfectly fine for you to already be doing your work on. > >>it always try to go with local cpu with same pxm. > > > >The problem is we really shouldn't be calling work_for_cpu in this case > >since we are already on the correct CPU. What probably should be > >happening is that pci_call_probe should be doing a check to see if the > >current CPU is already contained within the device node map and if so > >just call local_pci_probe directly. That way you can avoid deadlocking > >the system by trying to flush the CPU queue of the CPU you are currently on. > > > That's the patch that Michael Tsirkin posted for a fix, > but it was noted that if you have the case where the _same_ driver is used for vf & pf, > other deadlocks may occur. > It would work in the case of ixgbe/ixgbevf, but not for something like > the Mellanox pf/vf driver (which is the same). > I think our conclusion was this is a false positive for Mellanox. If not, we need to understand what the deadlock is better. > > > >Alex > >-- > >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 -- 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
