On Mon, Mar 14, 2022 at 09:01:12PM +0100, Tobias Waldekranz wrote: > On Mon, Mar 14, 2022 at 19:55, Vladimir Oltean <olteanv@xxxxxxxxx> wrote: > > On Mon, Mar 14, 2022 at 06:56:49PM +0200, Vladimir Oltean wrote: > >> > diff --git a/net/dsa/port.c b/net/dsa/port.c > >> > index 58291df14cdb..1a17a0efa2fa 100644 > >> > --- a/net/dsa/port.c > >> > +++ b/net/dsa/port.c > >> > @@ -240,6 +240,10 @@ static int dsa_port_switchdev_sync_attrs(struct dsa_port *dp, > >> > if (err && err != -EOPNOTSUPP) > >> > return err; > >> > > >> > + err = dsa_port_mst_enable(dp, br_mst_enabled(br), extack); > >> > + if (err && err != -EOPNOTSUPP) > >> > + return err; > >> > >> Sadly this will break down because we don't have unwinding on error in > >> place (sorry). We'd end up with an unoffloaded bridge port with > >> partially synced bridge port attributes. Could you please add a patch > >> previous to this one that handles this, and unoffloads those on error? > > > > Actually I would rather rename the entire dsa_port_mst_enable() function > > to dsa_port_mst_validate() and move it to the beginning of dsa_port_bridge_join(). > > This simplifies the unwinding that needs to take place quite a bit. > > Well you still need to unwind vlan filtering if setting the ageing time > fails, which is the most complicated one, right? Yes, but we can leave that for another day :) ...ergo > Should the unwinding patch still be part of this series then? no. > Still, I agree that _validate is a better name, and then _bridge_join > seems like a more reasonable placement. > > While we're here, I actually made this a hard error in both scenarios > (but forgot to update the log - will do that in v4, depending on what we > decide here). There's a dilemma: > > - When reacting to the attribute event, i.e. changing the mode on a > member we're apart of, we _can't_ return -EOPNOTSUPP as it will be > ignored, which is why dsa_port_mst_validate (nee _enable) returns > -EINVAL. > > - When joining a bridge, we _must_ return -EOPNOTSUPP to trigger the > software fallback. > > Having something like this in dsa_port_bridge_join... > > err = dsa_port_mst_validate(dp); > if (err == -EINVAL) > return -EOPNOTSUPP; > else if (err) > return err; > > ...works I suppose, but feels somewhat awkwark. Any better ideas? What you can do is follow the model of dsa_switch_supports_uc_filtering(), and create a dsa_switch_supports_mst() which is called inside an "if br_mst_enabled(br)" check, and returns bool. When false, you could return -EINVAL or -EOPNOTSUPP, as appropriate. This is mostly fine, except for the pesky dsa_port_can_configure_learning(dp) check :) So while you could name it dsa_port_supports_mst() and pass it a dsa_port, the problem is that you can't put the implementation of this new dsa_port_supports_mst() next to dsa_switch_supports_uc_filtering() where it would be nice to sit for symmetry, because the latter is static inline and we're missing the definition of dsa_port_can_configure_learning(). So.. the second best thing is to keep dsa_port_supports_mst() in the same place where dsa_port_mst_enable() currently is. What do you think?
