wifi: auto-activate devices as soon as the first scan finishesbg/wifi-scan

Currently if we detect that a scan finished in
_scan_notify_is_scanning(), we call immediately _scan_kickoff() (which
might start a new scan) and then we check again whether the device can
autoactivate or whether to remove the wifi-scan pending action.

This means that if the scan takes long enough, when
_scan_notify_is_scanning() is called, it is already time to start
another scan and the device activation will be delayed. It will be
delayed until the scan duration becomes shorter than the
exponentially-growing periodic scan interval.

Fix this by delaying the next scan immediately after a scan result.

Co-authored-by: Thomas Haller <thaller@redhat.com>

https://gitlab.freedesktop.org/NetworkManager/NetworkManager/-/issues/574

1 files changed, 17 insertions, 0 deletions

diff --git a/src/core/devices/wifi/nm-device-wifi.c b/src/core/devices/wifi/nm-device-wifi.c
index 6375412ce8..d9fdb4cc68 100644
--- a/src/core/devices/wifi/nm-device-wifi.c
+++ b/src/core/devices/wifi/nm-device-wifi.c
@@ -1745,6 +1745,23 @@ _scan_kickoff(NMDeviceWifi *self)
         return;
     }
 
+    if (priv->scan_last_complete_msec + 200 > now_msec) {
+        gint32 timeout_msec = priv->scan_last_complete_msec + 200 - now_msec;
+
+        /* after a scan just completed, it is ratelimited for another 200 msec. This is in
+         * addition to our rate limiting above (where scanning can take longer than our rate limit
+         * duration).
+         *
+         * This gives the device a chance to autoconnect. Also, if a scanning just completed,
+         * we want to back off a bit before starting again. */
+        _LOGT_scan("kickoff: don't scan (rate limited for another %d.%03d sec after previous scan)",
+                   timeout_msec / 1000,
+                   timeout_msec % 1000);
+        nm_clear_g_source(&priv->scan_kickoff_timeout_id);
+        priv->scan_kickoff_timeout_id = g_timeout_add(timeout_msec, _scan_kickoff_timeout_cb, self);
+        return;
+    }
+
     if (priv->scan_explicit_requested) {
         if (!priv->scan_explicit_allowed) {
             _LOGT_scan("kickoff: don't scan (explicit scan requested but not allowed)");