Opened 3 years ago

#17967 new defect

Reconfiguration fails while doing CAC

Reported by: reinerh Owned by: developers
Priority: normal Milestone: Barrier Breaker 14.07
Component: base system Version: Barrier Breaker 14.07
Keywords: netifd hostapd dfs cac Cc:


There is a problem with netifd and wifi reconfiguration while hostapd is doing CAC.
Because of hostapd patch 490-scan_wait.patch, hostapd will only daemonize/fork,
when it has finished setting up the interface.
And only after the fork the PID is registered at netifd via wireless_add_process.
But if a DFS channel is configured, hostapd will do CAC first, which takes a minute
(or even 10 minutes for some channels) to complete.

If the user decides to choose another channel in this time and does a "wifi reload",
netifd can't kill the running hostapd process, because it doesn't know its PID yet.
The hostapd process which is then spawned fails to start (because there is still
a hostapd process running) and no successive attempt to configure wifi succeeds.

I could workaround that by removing the 490-scan_wait.patch, so that hostapd
forks immediately and netifd gets its PID, and haven't noticed any side effects yet.
But there is probably a cleaner solution.

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