netdev - RE: [net-next 12/14] i40e: allow i40e_update_filter

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Date:   Tue, 14 Feb 2017 17:42:14 +0000
From:   "Keller, Jacob E" <jacob.e.keller@...el.com>
To:     Sergei Shtylyov <sergei.shtylyov@...entembedded.com>,
        "Kirsher, Jeffrey T" <jeffrey.t.kirsher@...el.com>,
        "davem@...emloft.net" <davem@...emloft.net>
CC:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "nhorman@...hat.com" <nhorman@...hat.com>,
        "sassmann@...hat.com" <sassmann@...hat.com>,
        "jogreene@...hat.com" <jogreene@...hat.com>
Subject: RE: [net-next 12/14] i40e: allow i40e_update_filter_state to skip
 broadcast filters

> -----Original Message-----
> From: Sergei Shtylyov [mailto:sergei.shtylyov@...entembedded.com]
> Sent: Sunday, February 12, 2017 2:18 AM
> To: Kirsher, Jeffrey T <jeffrey.t.kirsher@...el.com>; davem@...emloft.net
> Cc: Keller, Jacob E <jacob.e.keller@...el.com>; netdev@...r.kernel.org;
> nhorman@...hat.com; sassmann@...hat.com; jogreene@...hat.com
> Subject: Re: [net-next 12/14] i40e: allow i40e_update_filter_state to skip
> broadcast filters
> 
> Hello!
> 
> On 2/12/2017 8:30 AM, Jeff Kirsher wrote:
> 
> > From: Jacob Keller <jacob.e.keller@...el.com>
> >
> > Fix a bug where we modified the mac_filter_hash while outside a lock,
> > when handling addition of broadcast filters.
> >
> > Normally, we add filters to firmware by batching the additions into
> > lists and issuing 1 update for every few filters. Broadcast filters are
> > handled differently, by instead setting the broadcast promiscuous mode
> > flags. In order to make sure the 1<->1 mapping of filters in our
> > addition array lined up with filters in the hlist tmp_add_list, we had
> > to remove the filter and move it back to the main hash. However, we
> > didn't do this under lock, which could cause consistency problems for
> > the list.
> >
> > Fix this by updating i40e_update_filter_state logic so that it knows to
> > avoid broadcast filters. This ensures that we don't have to remove the
> > filter separately, and can put it back using the normal flow.
> >
> > Change-ID: Id288fade80b3e3a9a54b68cc249188cb95147518
> > Signed-off-by: Jacob Keller <jacob.e.keller@...el.com>
> > Tested-by: Andrew Bowers <andrewx.bowers@...el.com>
> > Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@...el.com>
> > ---
> >  drivers/net/ethernet/intel/i40e/i40e_main.c | 37
> ++++++++++++++++++++++-------
> >  1 file changed, 29 insertions(+), 8 deletions(-)
> >
> > diff --git a/drivers/net/ethernet/intel/i40e/i40e_main.c
> b/drivers/net/ethernet/intel/i40e/i40e_main.c
> > index fa4a04d..06c80d4 100644
> > --- a/drivers/net/ethernet/intel/i40e/i40e_main.c
> > +++ b/drivers/net/ethernet/intel/i40e/i40e_main.c
> > @@ -1843,6 +1843,31 @@ static void i40e_undo_filter_entries(struct i40e_vsi
> *vsi,
> >  }
> >
> >  /**
> > + * i40e_next_entry - Get the next non-broadcast filter from a list
> > + * @f: pointer to filter in list
> > + *
> > + * Returns the next non-broadcast filter in the list. Required so that we
> > + * ignore broadcast filters within the list, since these are not handled via
> > + * the normal firmware update path.
> > + */
> > +static struct i40e_mac_filter *i40e_next_filter(struct i40e_mac_filter *f)
> > +{
> > +	while (f) {
> > +		f = hlist_entry(f->hlist.next,
> > +				typeof(struct i40e_mac_filter),
> > +				hlist);
> > +
> > +		/* keep going if we found a broadcast filter */
> > +		if (f && is_broadcast_ether_addr(f->macaddr))
> > +			continue;
> > +
> > +		break;
> 
>     Isn't it simpler to *break* on an inverted condition above?
> This way, *continue* isn;'t needed...
> 

When I wrote the code originally it seemed better, but now that I think about it, the inverted conditional isn't that much more complicated, so I'll change it.

Thanks,
Jake

> [...]
> 
> MBR, Sergei