Re: [PATCH 1/3] IB/vmw_pvrdma: Defer activating device until vmxnet3 link is up

[Doug Ledford <dledford-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>]

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On Tue, 2017-01-17 at 16:31 -0800, Adit Ranadive wrote:
> On Mon, Jan 16, 2017 at 09:38:58AM +0200, Leon Romanovsky wrote:
> > 
> > On Tue, Jan 10, 2017 at 11:15:39AM -0800, Adit Ranadive wrote:
> > > 
> > > From: Aditya Sarwade <asarwade-pghWNbHTmq7QT0dZR+AlfA@public.gmane.org>
> > > 
> > > Currently on bootup, ethernet drivers seem to load before RDMA
> > > ones
> > > in Linux. So while the vmxnet3 module is loaded before
> > > vmw_pvrdma,
> > > the vmxnet3 link state may not necessarily be enabled by the
> > > stack
> > > before pvrdma is loaded. This is a problem because if the pvrdma
> > > module is loaded on bootup (by installing it in /lib/modules/*),
> > > the pvrdma device comes up in a port down state.
> > > 
> > > Since this is the most common use case scenario, defer the
> > > activation
> > > of the device till the paired vmxnet3 link actually comes up. One
> > > downside of doing this is, if a user doesn't have the vmxnet3
> > > link
> > > up when the pvrdma driver is loaded, they may not see any output
> > > for ibv_devinfo until the paired vmxnet3 link is enabled too. The
> > > users somehow need to be aware of this.
> > > 
> > 
> > I wouldn't call it "fix", the more appropriate name is "hack".
> > It doesn't look right that users should be aware of such non-
> > intuitive
> > driver behavior.
> 
> Well its a partial fix for 4.10 to let the RDMA device come up
> correctly
> Since this is a RoCE device we want to mimic to eth port status for
> the
> RDMA link. Currently, for us there isnt an easy way to do this if the
> vmxnet3 device comes up after we have already registered the IB
> device.
> This patch moves the IB device registration to after the ethernet
> link is
> up.
> I wanted to get this in so that in the common case of VM power on,
> the 
> PVRDMA device is in the port active state along with the vmxnet3
> link.
> 
> Doug, any thoughts?

Yes, I'm wondering why the vmw_pvrdma driver doesn't detect link state
changes and act appropriately?

-- 
Doug Ledford <dledford-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
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