Re: [PATCH 1/1] RDMA/mlx5: Make mlx5 device work with ib_device_get_by_netdev

[Jason Gunthorpe <jgg@ziepe.ca>]

On Tue, Oct 18, 2022 at 11:24:43AM +0300, Leon Romanovsky wrote:
> On Sun, Oct 16, 2022 at 02:19:25AM -0400, Zhu Yanjun wrote:
> > From: Zhu Yanjun <yanjun.zhu@linux.dev>
> > 
> > Before mlx5 ib device is registered, the function ib_device_set_netdev
> > is not called to map the mlx5 ib device with the related net device.
> > 
> > As such, when the function ib_device_get_by_netdev is called to get ib
> > device, NULL is returned.
> > 
> > Other ib devices, such as irdma, rxe and so on, the function
> > ib_device_get_by_netdev can get ib device from the related net device.
> 
> Ohh, you opened Pandora box, everything around it looks half-backed.
> 
> mlx4 and mlx5 don't call to ib_device_set_netdev(), because they have
> .get_netdev() callback. This callback is not an easy task to eliminate
> and many internal attempts failed to eliminate them.
> 
> This caused to very questionable ksmbd_rdma_capable_netdev()
> implementation where ksmbd first checked internal ib_dev callback
> and tried to use ib_device_get_by_netdev(). And to smc_ib, which
> didn't even bother to use ib_device_get_by_netdev().

Oh really? Those APIs were only for driver use, not ULP :(

Jason