Re: [PATCH] net/netvsc: use rte_eth_dev_set_mtu to set VF MTU

[Stephen Hemminger <stephen@networkplumber.org>]

On Fri, 19 Jul 2024 21:39:04 +0100
Ferruh Yigit <ferruh.yigit@amd.com> wrote:

> > --- a/drivers/net/netvsc/hn_vf.c
> > +++ b/drivers/net/netvsc/hn_vf.c
> > @@ -264,7 +264,7 @@ int hn_vf_add(struct rte_eth_dev *dev, struct hn_data *hv)
> >  			goto exit;
> >  		}
> >  
> > -		ret = hn_vf_mtu_set(dev, dev->data->mtu);
> > +		ret = rte_eth_dev_set_mtu(port, dev->data->mtu);
> >  
> 
> As 'rte_eth_dev_set_mtu()' calls 'hn_vf_mtu_set()' in the call chain,
> won't it cause same problem?

The port is the vf so it will call the set_mtu on the VF not the netvsc
device so it is not in the call chain.

> 
> Does it help to make unlocked version of 'hn_vf_mtu_set()':
> ```
> _hn_vf_mtu_set()
> 	// set mtu without lock
> 
> hn_vf_mtu_set()
> 	lock()
> 	_hn_vf_mtu_set()
> 	unlock()
> ```

That was original proposal, but using rte_eth_dev_set_mtu() on the VF
port has more error checking.