[Bug 258948] [net80211] AP + STA configuration can lead to the AP VAP stopping traffic after STA scan
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Date: Tue, 05 Oct 2021 15:35:54 UTC
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=258948 Bug ID: 258948 Summary: [net80211] AP + STA configuration can lead to the AP VAP stopping traffic after STA scan Product: Base System Version: CURRENT Hardware: Any OS: Any Status: New Severity: Affects Only Me Priority: --- Component: wireless Assignee: wireless@FreeBSD.org Reporter: adrian@freebsd.org Here's a fun very hilarious corner case when you start using STA + AP configurations. My test setup: * An AR9380 radio with a STA VAP (DWDS child / upstream facing) and AP VAP * A second AR9380 radio with AP VAPs with DWDS parent / downstream facing configured * bridging between them all When the STA VAP decides that it needs to scan to find a new AP, sometimes the AP will stop traffic / 802.1x negotiation, even after the STA VAP finishes scanning and reassociates. After like a year of narrowing things down, I've finally figured out what's going on: * there are STA beacon miss events, which lead net80211/wpa_supplicant to move from RUN to SCAN state * this calls markwaiting(), which will mark all the other VAPs as waiting * this calls vap->iv_newstate(vap, INIT, ...) to set the state to INIT for each other VAP on the radio * Then some packet is transmitted on the AP VAP via ieee80211_vap_transmit(), and since it's not in the RUN state, the OACTIVE flag is set on vap->iv_ifp * .. time passes .. * Finally, the STA VAP transitions through its states to eventually hit RUN * .. which will call wakeupwaiting() * .. which iterates over all the VAPs again and calls vap->iv_newstate(vap, RUN, ...) .. now at this point, the VAP specific mode newstate code and the driver specific newstate code is running, but! Note! These codepaths aren't going via the ieee80211_new_state() / ieee80211_new_state_locked(), and the only path that clears OACTIVE is in here. * Then eventually a call to ieee80211_new_state*() is done for the AP VAP, setting the state to RUN * However! The deferred taskqueue (ieee80211_new_state_cb()) code sees a state going RUN->RUN, rather than RUN->INIT->RUN, thus it does NOT clear OACTIVE. This is why associations worked fine, but the raw BPF sends did not - ieee80211_output() (used by BPF) checks OACTIVE flag and just drops the packets. The real eventual fix is removing OACTIVE, but this does require a pass through all the wifi drivers to make sure none of them are using OACTIVE anymore. The temporary fix is just to clear the OACTIVE flag in ieee80211_new_state_cb() if the state is RUN, even if it's RUN->RUN. -- You are receiving this mail because: You are the assignee for the bug.