On Mon, 27 May 2024 at 15:59, Bjoern A. Zeeb <b...@freebsd.org> wrote:
Last I got fed up by SCAN problems this afternoon and started > investigating. Have other people (with iwn/iwm/iwlwifi or others) noticed > the fact that once you are associated with a channel in a band (say Channel > 6) you will not get scan results for 11a/5Ghz anymore? Or that > sometimes scanning will "just stop" (way beyond scanvalid interval) and > triggering a manual scan (or from wpa_cli) you either just get the old > cache > or EINPROGRESS? (checking ddb on-off I noticed that the scan got stuck > in ACTIVE or BGSCAN was on suddenly despite IEEE80211_FEXT_SCAN_OFFLOAD > is set given iwlwifi does hw_scan and we never enable background > scanning). > I know this has bugged me in the past a lot on iwm(4) on 8xxx chipsets > and ifconfig down/ifconifg mode auto/ifconfig up fixed it again. > In case more people have observed similar things, please let me know > so we can properly track this. > Oh, wow, this is still a problem? Aiee. I remember fixing a WHOLE lot of races in the non scan offload and the then-new scan full offload paths. I'll see if I can reproduce it on iwn(4) (which supports full scan offload) and see what happens. A lot of this stuff originally used flags in multiple threads without actually using atomics + barriers and it was just super easy to get stuck :( -adrian
