Re: [Intel-wired-lan] [PATCH net] ixgbe: only access vfinfo and mv_list under RCU lock

[Corinna Vinschen <vinschen@redhat.com>]

On Apr 16 09:23, Loktionov, Aleksandr wrote:
> > From: Intel-wired-lan <intel-wired-lan-bounces@osuosl.org> On Behalf
> > [...]
> > @@ -9744,17 +9781,23 @@ static int ixgbe_ndo_get_vf_stats(struct
> > net_device *netdev, int vf,
> >  				  struct ifla_vf_stats *vf_stats)
> >  {
> >  	struct ixgbe_adapter *adapter = ixgbe_from_netdev(netdev);
> > +	struct vf_data_storage *vfinfo;
> > 
> >  	if (vf < 0 || vf >= adapter->num_vfs)
> >  		return -EINVAL;
> > 
> > -	vf_stats->rx_packets = adapter->vfinfo[vf].vfstats.gprc;
> > -	vf_stats->rx_bytes   = adapter->vfinfo[vf].vfstats.gorc;
> > -	vf_stats->tx_packets = adapter->vfinfo[vf].vfstats.gptc;
> > -	vf_stats->tx_bytes   = adapter->vfinfo[vf].vfstats.gotc;
> > -	vf_stats->multicast  = adapter->vfinfo[vf].vfstats.mprc;
> > +	rcu_read_lock();
> > +	vfinfo = rcu_dereference(adapter->vfinfo);
> > +	if (vfinfo) {
> > +		vf_stats->rx_packets = vfinfo[vf].vfstats.gprc;
> > +		vf_stats->rx_bytes   = vfinfo[vf].vfstats.gorc;
> > +		vf_stats->tx_packets = vfinfo[vf].vfstats.gptc;
> > +		vf_stats->tx_bytes   = vfinfo[vf].vfstats.gotc;
> > +		vf_stats->multicast  = vfinfo[vf].vfstats.mprc;
> > +	}
> > +	rcu_read_unlock();
> > 
> > -	return 0;
> > +	return vfinfo ? 0 : -EINVAL;
> Before it returned always success, but now it will break 'ip link show dev' in short window when SR-IOV is being torn down.
> For me it looks like UAPI regression.

Good point.  I'll change that back for a v2, just waiting for more
feedback.


Thanks,
Corinna