On Fri, Jul 23, 2021 at 10:12:08AM +0200, Christoph Hellwig wrote:

On Tue, Jul 20, 2021 at 02:42:56PM -0300, Jason Gunthorpe wrote:

quoted

Like vfio_pci_try_bus_reset() this code wants to reset all of the devices
in the "reset group" which is the same membership as the device set.

Instead of trying to reconstruct the device set from the PCI list go
directly from the device set's device list to execute the reset.

The same basic structure as vfio_pci_try_bus_reset() is used. The
'vfio_devices' struct is replaced with the device set linked list and we
simply sweep it multiple times under the lock.

This eliminates a memory allocation and get/put traffic and another
improperly locked test of pci_dev_driver().

Looks fine.  But oh gad is that locking scheme awful..

I hope that the address space patches Alex has been working on will
help this.

And as I wrote it I was wondering if we can swap the dev_set lock for
all these other locks and just delete the whole thing..

Thanks,
Jason