Re: [PATCH net-next v5 03/14] net: move promiscuity handling into netdev_rx_mode_work (ddeab417d841)

[sdf.kernel@gmail.com]

> This is an AI-generated review of your patch. The human sending this
> email has considered the AI review valid, or at least plausible.
> ---
> net: move promiscuity handling into netdev_rx_mode_work
> 
> This commit moves unicast promiscuity tracking into netdev_rx_mode_work so
> it runs under netdev_ops_lock instead of the addr_lock spinlock. It also
> changes ASSERT_RTNL() to netdev_ops_assert_locked() in several functions
> called from the work queue.
> 
> > diff --git a/net/core/dev.c b/net/core/dev.c
> > index 0efac0c730077..08dac9c759996 100644
> > --- a/net/core/dev.c
> > +++ b/net/core/dev.c
> > @@ -9586,7 +9586,7 @@ int __dev_set_promiscuity(struct net_device *dev, int inc, bool notify)
> >  	kuid_t uid;
> >  	kgid_t gid;
> >  
> > -	ASSERT_RTNL();
> > +	netdev_ops_assert_locked(dev);
> 
> Can this cause a lockdep assertion failure for unconverted ops-locked devices
> using the legacy RX mode path?

Correct and addressed later in the series in "net: warn ops-locked drivers
still using ndo_set_rx_mode". Don't think there is a better way to split
the patches...

> Replacing ASSERT_RTNL() with netdev_ops_assert_locked(dev) asserts that
> dev->lock is held for devices where netdev_need_ops_lock(dev) is true.
> 
> [ ... ]
> 
> > diff --git a/net/core/dev_addr_lists.c b/net/core/dev_addr_lists.c
> > index a05db3ac43ea9..61589537b2d3d 100644
> > --- a/net/core/dev_addr_lists.c
> > +++ b/net/core/dev_addr_lists.c
> [ ... ]
> > @@ -1295,20 +1337,16 @@ void __dev_set_rx_mode(struct net_device *dev)
> >  	if (!netif_device_present(dev))
> >  		return;
> >  
> > -	if (ops->ndo_set_rx_mode_async) {
> > +	if (ops->ndo_set_rx_mode_async || ops->ndo_change_rx_flags) {
> >  		netif_rx_mode_queue(dev);
> >  		return;
> >  	}
> >  
> > -	if (!(dev->priv_flags & IFF_UNICAST_FLT)) {
> > -		if (!netdev_uc_empty(dev) && !dev->uc_promisc) {
> > -			__dev_set_promiscuity(dev, 1, false);
> > -			dev->uc_promisc = true;
> > -		} else if (netdev_uc_empty(dev) && dev->uc_promisc) {
> > -			__dev_set_promiscuity(dev, -1, false);
> > -			dev->uc_promisc = false;
> > -		}
> > -	}
> > +	/* Legacy path for non-ops-locked HW devices. */
> > +
> > +	promisc_inc = netif_uc_promisc_update(dev);
> > +	if (promisc_inc)
> > +		__dev_set_promiscuity(dev, promisc_inc, false);
> 
> If an ops-locked device has not yet been converted to implement the new
> ndo_set_rx_mode_async or ndo_change_rx_flags callbacks, this legacy path
> will be executed.

Same here, addressed later in the series in "net: warn ops-locked drivers
still using ndo_set_rx_mode".

> 
> When a secondary unicast address is added to such a device (e.g., by
> bringing up a macvlan interface over it) and the device lacks
> IFF_UNICAST_FLT, netif_uc_promisc_update() returns 1. This triggers a
> synchronous inline call to __dev_set_promiscuity(dev, 1, false).
> 
> Since __dev_set_rx_mode() is invoked from address list helpers like
> dev_uc_add() which only hold rtnl_lock() and netif_addr_lock_bh(dev),
> dev->lock is not held, which would trigger the new assertion in
> __dev_set_promiscuity().

Same.