linux-kernel - Re: [PATCH net v2] lan966x: Fix crash when adding interface under a lag

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Message-ID: <20240212083229.tg3cabp4iee3p6tq@DEN-DL-M31836.microchip.com>
Date: Mon, 12 Feb 2024 09:32:29 +0100
From: Horatiu Vultur <horatiu.vultur@...rochip.com>
To: Jakub Kicinski <kuba@...nel.org>
CC: <davem@...emloft.net>, <edumazet@...gle.com>, <pabeni@...hat.com>,
	<UNGLinuxDriver@...rochip.com>, <netdev@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, Michal Swiatkowski
	<michal.swiatkowski@...ux.intel.com>
Subject: Re: [PATCH net v2] lan966x: Fix crash when adding interface under a
 lag

The 02/12/2024 09:10, Horatiu Vultur wrote:
> The 02/09/2024 13:52, Jakub Kicinski wrote:
> 
> Hi Jakub,
> 
> > 
> > On Tue, 6 Feb 2024 13:30:54 +0100 Horatiu Vultur wrote:
> > >       for (lag = 0; lag < lan966x->num_phys_ports; ++lag) {
> > > -             struct net_device *bond = lan966x->ports[lag]->bond;
> > > +             struct lan966x_port *port = lan966x->ports[lag];
> > >               int num_active_ports = 0;
> > > +             struct net_device *bond;
> > >               unsigned long bond_mask;
> > >               u8 aggr_idx[16];
> > >
> > > -             if (!bond || (visited & BIT(lag)))
> > > +             if (!port || !port->bond || (visited & BIT(lag)))
> > >                       continue;
> > >
> > > +             bond = port->bond;
> > >               bond_mask = lan966x_lag_get_mask(lan966x, bond);
> > >
> > >               for_each_set_bit(p, &bond_mask, lan966x->num_phys_ports) {
> > >                       struct lan966x_port *port = lan966x->ports[p];
> > >
> > > +                     if (!port)
> > > +                             continue;
> > 
> > Why would lan966x_lag_get_mask() set a bit for a port that doesn't
> > exist? Earlier check makes sense. This one seems too defensive.
> 
> You are right, the lan966x_lag_get_mask() will not set a bit for a port
> that doesn't exist[1]. Therefore this check is not needed.
> 
> [1] https://elixir.bootlin.com/linux/latest/source/drivers/net/ethernet/microchip/lan966x/lan966x_lag.c#L354

While trying to rebase on net, the next version of this patch, I have seen that
actually this version was accepted even though it was marked as "Changes
Requested".
The commit sha is: 15faa1f67ab405d47789d4702f587ec7df7ef03e

How do you prefer to go forward from here?
- do you want to revert this and then I will send a new version?
- should I send a patch that just removes this unneeded check?
- any other suggestion?

> 
> > --
> > pw-bot: cr
> 
> -- 
> /Horatiu

-- 
/Horatiu