Re: [PATCH 4/4] station: rate limit packet loss roam scans

[Denis Kenzior <denkenz@gmail.com>]

Hi James,

On 10/30/23 08:48, James Prestwood wrote:
> The packet loss handler puts a higher priority on roaming compared
> to the low signal roam path. This is generally beneficial since this
> event usually indicates some problem with the BSS and generally is
> an indicator that a disconnect will follow sometime soon.
> 
> But by immediately issuing a scan we run the risk of causing many
> successive scans if more packet loss events arrive following
> the roam scans (and if no candidates are found). Logs provided
> further.
> 
> To help with this handle the first event with priority and
> immediately issue a roam scan. If another event comes in within a
> certain timeframe (2 seconds) don't immediately scan, but instead
> rearm the roam timer instead of issuing a scan. This also handles
> the case of a low signal roam scan followed by a packet loss
> event. Delaying the roam will at least provide some time for packets
> to get out in between roam scans.
> 
> Logs were snipped to be less verbose, but this cycled happened
> 5 times prior. In total 7 scans were issued in 5 seconds which may
> very well have been the reason for the local disconnect:
> 
> Oct 27 16:23:46 src/station.c:station_roam_failed() 9
> Oct 27 16:23:46 src/wiphy.c:wiphy_radio_work_done() Work item 29 done
> Oct 27 16:23:47 src/netdev.c:netdev_mlme_notify() MLME notification Notify CQM(64)
> Oct 27 16:23:47 src/station.c:station_packets_lost() Packets lost event: 10
> Oct 27 16:23:47 src/station.c:station_roam_scan() ifindex: 9
> Oct 27 16:23:47 src/wiphy.c:wiphy_radio_work_insert() Inserting work item 30
> Oct 27 16:23:47 src/wiphy.c:wiphy_radio_work_next() Starting work item 30
> Oct 27 16:23:47 src/station.c:station_start_roam() Using cached neighbor report for roam
> Oct 27 16:23:47 src/scan.c:scan_notify() Scan notification Trigger Scan(33)
> Oct 27 16:23:47 src/scan.c:scan_request_triggered() Active scan triggered for wdev a
> Oct 27 16:23:47 src/scan.c:scan_notify() Scan notification New Scan Results(34)
> Oct 27 16:23:47 src/netdev.c:netdev_link_notify() event 16 on ifindex 9
> ... scan results ...
> Oct 27 16:23:47 src/station.c:station_roam_failed() 9
> Oct 27 16:23:47 src/wiphy.c:wiphy_radio_work_done() Work item 30 done
> Oct 27 16:23:47 src/netdev.c:netdev_mlme_notify() MLME notification Notify CQM(64)
> Oct 27 16:23:47 src/station.c:station_packets_lost() Packets lost event: 10
> Oct 27 16:23:47 src/station.c:station_roam_scan() ifindex: 9
> Oct 27 16:23:47 src/wiphy.c:wiphy_radio_work_insert() Inserting work item 31
> Oct 27 16:23:47 src/wiphy.c:wiphy_radio_work_next() Starting work item 31
> Oct 27 16:23:47 src/station.c:station_start_roam() Using cached neighbor report for roam
> Oct 27 16:23:47 src/scan.c:scan_notify() Scan notification Trigger Scan(33)
> Oct 27 16:23:47 src/scan.c:scan_request_triggered() Active scan triggered for wdev a
> Oct 27 16:23:48 src/scan.c:scan_notify() Scan notification New Scan Results(34)
> Oct 27 16:23:48 src/netdev.c:netdev_link_notify() event 16 on ifindex 9
> ... scan results ...
> Oct 27 16:23:48 src/station.c:station_roam_failed() 9
> Oct 27 16:23:48 src/wiphy.c:wiphy_radio_work_done() Work item 31 done
> Oct 27 16:23:48 src/netdev.c:netdev_mlme_notify() MLME notification Notify CQM(64)
> Oct 27 16:23:48 src/station.c:station_packets_lost() Packets lost event: 10
> Oct 27 16:23:48 src/station.c:station_roam_scan() ifindex: 9
> Oct 27 16:23:48 src/wiphy.c:wiphy_radio_work_insert() Inserting work item 32
> Oct 27 16:23:48 src/wiphy.c:wiphy_radio_work_next() Starting work item 32
> Oct 27 16:23:48 src/station.c:station_start_roam() Using cached neighbor report for roam
> Oct 27 16:23:48 src/scan.c:scan_notify() Scan notification Trigger Scan(33)
> Oct 27 16:23:48 src/scan.c:scan_request_triggered() Active scan triggered for wdev a
> Oct 27 16:23:49 src/netdev.c:netdev_link_notify() event 16 on ifindex 9
> Oct 27 16:23:49 src/netdev.c:netdev_mlme_notify() MLME notification Del Station(20)
> Oct 27 16:23:49 src/netdev.c:netdev_mlme_notify() MLME notification Deauthenticate(39)
> Oct 27 16:23:49 src/netdev.c:netdev_deauthenticate_event()
> Oct 27 16:23:49 src/netdev.c:netdev_mlme_notify() MLME notification Disconnect(48)
> Oct 27 16:23:49 src/netdev.c:netdev_disconnect_event()
> Oct 27 16:23:49 Received Deauthentication event, reason: 4, from_ap: false
> ---
>   src/station.c | 28 +++++++++++++++++++++++++++-
>   1 file changed, 27 insertions(+), 1 deletion(-)
> 

Applied, thanks.

Regards,
-Denis