Re: User SIW fails matching device

[Jason Gunthorpe <jgg@ziepe.ca>]

On Fri, Jul 12, 2019 at 07:57:19PM +0530, Potnuri Bharat Teja wrote:
> Hi all,
> I observe the following behavior on one of my machines configured for siw.
> 
> Issue:
> SIW device gets wrong device ops (HW/real rdma driver device ops) instead of
> siw device ops due to improper device matching.
> 
> Root-cause:
> In libibverbs, during user cma initialisation, for each entry from the driver 
> list, sysfs device is checked for matching name or device.
> If the siw/rxe driver is at the head of the list, then sysfs device matches 
> properly with the corresponding siw driver and gets the corresponding siw/rxe 
> device ops. Now, If the siw/rxe driver is after the real HW driver cxgb4/mlx5 
> respectively in the driver list, then siw sysfs device matches pci device and 
> wrongly gets the device ops of HW driver (cxgb4/mlx5).
> 
> Below debug prints from verbs_register_driver() and driver_list entries, where 
> siw is after cxgb4. I see verbs alloc context landing in cxgb4_alloc_context 
> instead of siw_alloc_context, thus breaking user siw.
> 
> <debug> verbs_register_driver_22: 184: driver 0x176e370
> <debug> verbs_register_driver_22: 185: name ipathverbs
> <debug> verbs_register_driver_22: 184: driver 0x176f6a0
> <debug> verbs_register_driver_22: 185: name cxgb4
> <debug> verbs_register_driver_22: 184: driver 0x176fd50
> <debug> verbs_register_driver_22: 185: name cxgb3
> <debug> verbs_register_driver_22: 184: driver 0x1777020
> <debug> verbs_register_driver_22: 185: name rxe
> <debug> verbs_register_driver_22: 184: driver 0x1770a30
> <debug> verbs_register_driver_22: 185: name siw
> <debug> verbs_register_driver_22: 184: driver 0x1771120
> <debug> verbs_register_driver_22: 185: name mlx4
> <debug> verbs_register_driver_22: 184: driver 0x1771990
> <debug> verbs_register_driver_22: 185: name mlx5
> <debug> verbs_register_driver_22: 184: driver 0x1771ff0
> <debug> verbs_register_driver_22: 185: name efa
> 
> <debug> try_drivers: 372: driver 0x176e370, sysfs_dev 0x1776b20, name: ipathverbs
> <debug> try_drivers: 372: driver 0x176f6a0, sysfs_dev 0x1776b20, name: cxgb4
> <debug> try_drivers: 372: driver 0x176fd50, sysfs_dev 0x1776b20, name: cxgb3
> <debug> try_drivers: 372: driver 0x1777020, sysfs_dev 0x1776b20, name: rxe
> <debug> try_drivers: 372: driver 0x1770a30, sysfs_dev 0x1776b20, name: siw
> <debug> try_drivers: 372: driver 0x1771120, sysfs_dev 0x1776b20, name: mlx4
> <debug> try_drivers: 372: driver 0x1771990, sysfs_dev 0x1776b20, name: mlx5
> <debug> try_drivers: 372: driver 0x1771ff0, sysfs_dev 0x1776b20, name: efa
> 
> Proposed fix:
> I have the below fix that works. It adds siw/rxe driver to the HEAD of the 
> driver list and the rest to the tail. I am not sure if this fix is the ideal 
> one, so I am attaching it to this mail.

Update your rdma-core to latest and this will be fixed fully by using
netlink to match the siw device..

Jason