On tor, mar 10, 2022 at 17:07, Vladimir Oltean <olteanv@xxxxxxxxx> wrote:
> On Thu, Mar 10, 2022 at 04:00:52PM +0100, Hans Schultz wrote:
>> >> + brport = dsa_port_to_bridge_port(dp);
>> >
>> > Since this is threaded interrupt context, I suppose it could race with
>> > dsa_port_bridge_leave(). So it is best to check whether "brport" is NULL
>> > or not.
>> >
>> Would something like:
>> if (dsa_is_unused_port(chip->ds, port))
>> return -ENODATA;
>>
>> be appropriate and sufficient for that?
>
> static inline
> struct net_device *dsa_port_to_bridge_port(const struct dsa_port *dp)
> {
> if (!dp->bridge)
> return NULL;
>
> if (dp->lag)
> return dp->lag->dev;
> else if (dp->hsr_dev)
> return dp->hsr_dev;
>
> return dp->slave;
> }
>
> Notice the "dp->bridge" check. The assignments are in dsa_port_bridge_create()
> and in dsa_port_bridge_destroy(). These functions assume rtnl_mutex protection.
> The question was how do you serialize with that, and why do you assume
> that dsa_port_to_bridge_port() returns non-NULL.
>
> So no, dsa_is_unused_port() would do absolutely nothing to help.
I was thinking in indirect terms (dangerous I know :-).
But wrt the nl lock, I wonder when other threads could pull the carpet
away under this, and so I might have to wait till after the last call
(mv88e6xxx_g1_atu_loadpurge) to free the nl lock?
