On Tue Apr 19, 2022 at 11:18 AM CEST, Nicolas Escande wrote: > On Sun Apr 17, 2022 at 11:18 AM CEST, Jouni Malinen wrote: > > Why is this removing the use of WPA_DRIVER_FLAGS_DFS_OFFLOAD completely > > here? I'm not completely sure I understood what kind of a case could > > have allowed ACS to select a DFS channel incorrectly. Maybe that is > > something that should be addressed in the ACS implementation instead? > > > > Please note that the DFS offload cases might use different style for > > configuring the DFS operations, so it is not clear whether the > > ieee80211h parameter is really applicable in all such cases and this > > type of a change could result in breaking something that is already > > deployed. > > So this code fetches the channels supported by the hardware and applies > flags on it depending on whether or not we can use them and under what > conditions. So for a regular driver (one that does not sets the > WPA_DRIVER_FLAGS_DFS_OFFLOAD flag), when DFS is disabled by hostapd conf, > any DFS channel will be flagged as disabled. This gets bypassed when the > driver sets WPA_DRIVER_FLAGS_DFS_OFFLOAD. > > From what I understood, the DFS offload flag means that the driver > itself should react to DFS events and handle things like CAC wait times. > It shouldn't imply anything for the rest of the code, it shouldn't hide > the fact that this channel shouldn't be used for example. > > This is problematic when doing ACS because we usually do not take into > account any channel that is flagged as disabled. So this applies to DFS > channels when the conf doesn't allow them. > > This lead me to cases where a conf that explicitely doesn't allow DFS > channel (ieee80211h=0) to be used with ACS still enabled, still selected > a DFS channel because the driver handles DFS itself with > WPA_DRIVER_FLAGS_DFS_OFFLOAD flag, but doesn't bypass our ACS > implementation with WPA_DRIVER_FLAGS_ACS_OFFLOAD. > > I understand that this could have implications but for me the "right" > behaviour should be : > - non usable channels should be flagged as such (so when conf doesn't > allow them exclude them) > - hostapd's ACS implem should select a "usable" channels from the list > (unless ACS is offloaded with WPA_DRIVER_FLAGS_ACS_OFFLOAD in which > case all bets are off) > > What do you think ? > > > -- > > Jouni Malinen PGP id EFC895FA Hi Jouni, Any new input on this ? _______________________________________________ Hostap mailing list Hostap@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/hostap
