Re: User SIW fails matching device

[Potnuri Bharat Teja <bharat@chelsio.com>]

On Friday, July 07/12/19, 2019 at 20:05:46 +0530, Jason Gunthorpe wrote:
> 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..
> 
I pulled the latest rdma-core, still see the issue.

commit 7ef6077ec3201f661458297fea776746ba752843 (HEAD, upstream/master)
Merge: 837954ff677c 95934b61a74e
Author: Jason Gunthorpe <jgg@mellanox.com>
Date:   Thu Jul 11 16:18:06 2019 -0300

    Merge pull request #539 from jgunthorpe/netlink

        Use netlink to learn about ibdevs and their related chardevs

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Is there any corresponding kernel change or package dependency? I am currently 
on Doug's wip/dl-for-next branch.