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).
Alex
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