On Sat, Feb 04, 2023 at 09:48:24AM +0100, netdev@xxxxxxxxxxxxxxxxxxxx wrote: > On 2023-02-04 09:12, Simon Horman wrote: > > On Fri, Feb 03, 2023 at 10:44:22PM +0200, Vladimir Oltean wrote: > > > On Fri, Feb 03, 2023 at 09:20:22AM +0100, Simon Horman wrote: > > > > > else if (someflag) > > > > > dosomething(); > > > > > > > > > > For now only one flag will actually be set and they are mutually exclusive, > > > > > as they will not make sense together with the potential flags I know, but > > > > > that can change at some time of course. > > > > > > > > Yes, I see that is workable. I do feel that checking for other flags would > > > > be a bit more robust. But as you say, there are none. So whichever > > > > approach you prefer is fine by me. > > > > > > The model we have for unsupported bits in the > > > SWITCHDEV_ATTR_ID_PORT_PRE_BRIDGE_FLAGS > > > and SWITCHDEV_ATTR_ID_PORT_BRIDGE_FLAGS handlers is essentially this: > > > > > > if (flags & ~(supported_flag_mask)) > > > return -EOPNOTSUPP; > > > > > > if (flags & supported_flag_1) > > > ... > > > > > > if (flags & supported_flag_2) > > > ... > > > > > > I suppose applying this model here would address Simon's > > > extensibility concern. > > > > Yes, that is the model I had in mind. > > The only thing is that we actually need to return both 0 and -EOPNOTSUPP for > unsupported flags. The dynamic flag requires 0 when not supported (and > supported) AFAICS. > Setting a mask as 'supported' for a feature that is not really supported > defeats the notion of 'supported' IMHO. Just to clarify my suggestion one last time, it would be along the lines of the following (completely untested!). I feel that it robustly covers all cases for fdb_flags. And as a bonus doesn't need to be modified if other (unsupported) flags are added in future. if (fdb_flags & ~(DSA_FDB_FLAG_DYNAMIC)) return -EOPNOTSUPP; is_dynamic = !!(fdb_flags & DSA_FDB_FLAG_DYNAMIC) if (is_dynamic) state = MV88E6XXX_G1_ATU_DATA_STATE_UC_AGE_7_NEWEST; And perhaps for other drivers: if (fdb_flags & ~(DSA_FDB_FLAG_DYNAMIC)) return -EOPNOTSUPP; if (fdb_flags) return 0; Perhaps a helper would be warranted for the above. But in writing this I think that, perhaps drivers could return -EOPNOTSUPP for the DSA_FDB_FLAG_DYNAMIC case and the caller can handle, rather tha propagate, -EOPNOTSUPP. Returning -EOPNOTSUPP is the normal way to drivers to respond to requests for unsupported hardware offloads. Sticking to that may be clearner in the long run. That said, I do agree your current patch is correct given the flag that is defined (by your patchset).
