Timing out external scans?

Jouni Malinen j
Wed Mar 5 12:46:55 PST 2014

On Wed, Mar 05, 2014 at 11:57:04AM -0800, Ben Greear wrote:
> I saw a case testing ath10k where it appears the stations would not scan
> because they thought there were external scans pending.

It would be interesting to see a wpa_supplicant debug log showing that
if the state does not disappear automatically.

> Are those external scans supposed to time out after some time?

There is no additional timeout for this within wpa_supplicant, but
cfg80211 is supposed to indicate scan completion (either successful or
aborted). If that is missing for some reason and this cannot be fixed in
the kernel side, I guess we may have to consider adding a timeout for
that within wpa_supplicant as well. The only way I could think of this
happening today in a known possible way is if you run out of memory and
the nl80211 event indicating scan completion is dropped. All other cases
would likely indicate a bug of some sort somewhere (driver, cfg80211, or

> Once I restarted supplicant the stations immediately scanned and
> came up fine.

Please note that this is likely setting the netdev down which is
clearing a lot of cfg80211 state as well. Without seeing a verbose debug
log, it is difficult to say where the information about scan completion
was lost.
Jouni Malinen                                            PGP id EFC895FA

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