| Message ID | 20230329134455.4019868-1-raphael.melotte@mind.be |
|---|---|
| Headers | show |
| Series | hostapd: add support for AP+STA on the same radio | expand |
On Wed, Mar 29, 2023 at 03:44:51PM +0200, Raphaël Mélotte wrote: > This series contains patches from the OpenWrt project which add > support for running an AP and an STA on the same radio and still be > able to switch channels. A test for it has also been added. There was a comment on the second patch proposing a different approach for handling this, but that did not seem to go much further than that at least as far as anything on the hostap mailing list is concerned. Has there been any additional consideration on whether this coordination could happen within the driver itself or is this type of changes to hostapd and wpa_supplicant still needed and in use with OpenWrt? > Arnout Vandecappelle (Essensium/Mind) (1): > tests: AP+STA on same radio > > Felix Fietkau (3): > hostapd: ctrl_iface: add UPDATE command > Add support for AP+STA on a single radio > hostapd_reload_config: allow update of mode and frequency Why does the UPDATE command (from patch 1/4) reload the hostapd configuration file? Patch 2/4 seems to use UPDATE, but it does not change anything in the configuration file. Is the UPDATE command really needed when there is already SET command that can be used to update running configuration dynamically? Why does patch 1/4 modify hostapd_ctrl_iface_stop_ap()? The commit message does not seem to say anything about that change and I'm not sure the change is really correct. STOP_AP could be issued separately for each BSS. Patch 3/4 would change functionality that has been there for almost ten years.. This patch series does not seem to indicate what the use case is for configuration file changes since the only use here does not actually change the configuration file at all. The channel parameters for an operating AP may have changed dynamically during operation and it feels undesired to override those with the values that were specified in the configuration file in many cases. I can understand that there are cases where the channel should be switched, but the cleaner way for doing that would be to use the channel switch command and/or SET to override those parameters explicitly.
This series contains patches from the OpenWrt project which add support for running an AP and an STA on the same radio and still be able to switch channels. A test for it has also been added. Note that there is a major difference from the version in OpenWrt: the CSA count that is passed to hostapd was originally set to the counter the STA receives minus 1 ("count - 1"), while it has now been changed to be the same as the counter the STA receives ("count"). When testing the OpenWrt version with hwsim, the following kernel warning is triggered: """ /* the counter should never reach 0 */ WARN_ON_ONCE(!beacon->cntdwn_current_counter); """ It is triggered because by sending "count - 1", the AP is ready to switch channels - and reaches a count of 1 - one beacon interval sooner than the STA. As a consequence, the AP has to wait and send one more beacon, reaching a count of 0 (which should not happen, as the comment in the kernel code states). By sending the AP the same counter the STA receives, we make sure this doesn't happen. It has to be noted that what can *still* happen, is the AP receiving a counter that is "out of date". Indeed, if the supplicant takes time to give the AP the counter, we could end up in a situation where the station is ready to switch before the AP is (the reverse of the issue described above). From a quick test with hwsim however, this latter case does not seem to cause any problem with the channel switch (other than it taking more time). The 3 corresponding patches in OpenWrt are: package/network/services/hostapd/patches/340-reload_freq_change.patch package/network/services/hostapd/patches/360-ctrl_iface_reload.patch package/network/services/hostapd/patches/370-ap_sta_support.patch Arnout Vandecappelle (Essensium/Mind) (1): tests: AP+STA on same radio Felix Fietkau (3): hostapd: ctrl_iface: add UPDATE command Add support for AP+STA on a single radio hostapd_reload_config: allow update of mode and frequency hostapd/ctrl_iface.c | 67 +++++++++++++++++ src/ap/beacon.c | 5 -- src/ap/ctrl_iface_ap.c | 8 +- src/ap/hostapd.c | 50 +++++++++---- src/drivers/driver.h | 2 + src/drivers/driver_nl80211_event.c | 6 +- tests/hwsim/test_ap_csa.py | 115 +++++++++++++++++++++++++++++ wpa_supplicant/Makefile | 2 + wpa_supplicant/bss.c | 10 +++ wpa_supplicant/bss.h | 2 + wpa_supplicant/events.c | 44 ++++++++++- wpa_supplicant/main.c | 8 +- wpa_supplicant/wpa_supplicant.c | 70 ++++++++++++++++++ wpa_supplicant/wpa_supplicant_i.h | 7 ++ 14 files changed, 371 insertions(+), 25 deletions(-)