I am looking at implementing the FLR functionality in the xen-pciback driver and
found a mutex issue I am not entirely sure how to resolve.
In essence I am trying to call pci_reset_function() when a PCI device is
"attached" (using "bind") to the xen-pciback driver.
This means that when a user does:
echo "0000:01.07.0" > /sys/bus/pci/drivers/pciback/bind
we end up calling:
driver_bind:
device_lock(dev);
pcistub_probe:
pcistub_seize:
pcistub_init_device:
.. pci_enable_device()
--> want also to do pci_reset_function(), which calls
pci_dev_reset(dev, 0):
if (!0) {
device_lock(dev) <==== DEADLOCK
.. pci_disable_device()
So looking at the code I saw __pci_reset_function which I thought
would do the same as pci_reset_function but without locking.
However, it is actually the opposite - it is with the locking.
My thought is that one way to resolve this is by wrapping
pci_probe_reset_function with a EXPORT_SYMBOL_GPL and use that
instead. Or perhaps have a new function called
"pci_reset_function_locked" ?
Thoughts?
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