On Mon, Mar 14, 2022 at 22:20, Vladimir Oltean <olteanv@xxxxxxxxx> wrote: > 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. Agreed >> 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? I think that would mostly work. It would have to be positioned higher up in the file though, so that it can be called from _bridge_join. Unless we add a forward for it of course, but that seems to break with existing conventions.
