Re: [net-next RFC PATCH v4 03/15] net: dsa: hold rtnl_mutex when calling dsa_master_{setup,teardown}

[Florian Fainelli]

On 12/11/2021 11:57 AM, Ansuel Smith wrote:
> From: Vladimir Oltean <vladimir.oltean@xxxxxxx>
>
> DSA needs to simulate master tracking events when a binding is first
> with a DSA master established and torn down, in order to give drivers
> the simplifying guarantee that ->master_state_change calls are made
> only when the master's readiness state to pass traffic changes.
> master_state_change() provide a operational bool that DSA driver can use
> to understand if DSA master is operational or not.
> To avoid races, we need to block the reception of
> NETDEV_UP/NETDEV_CHANGE/NETDEV_GOING_DOWN events in the netdev notifier
> chain while we are changing the master's dev->dsa_ptr (this changes what
> netdev_uses_dsa(dev) reports).
>
> The dsa_master_setup() and dsa_master_teardown() functions optionally
> require the rtnl_mutex to be held, if the tagger needs the master to be
> promiscuous, these functions call dev_set_promiscuity(). Move the
> rtnl_lock() from that function and make it top-level.
>
> Signed-off-by: Vladimir Oltean <vladimir.oltean@xxxxxxx>
> Signed-off-by: Ansuel Smith <ansuelsmth@xxxxxxxxx>

Reviewed-by: Florian Fainelli <f.fainelli@xxxxxxxxx>
--
Florian