[PATCH v2 2/2] nl80211: fix simultaneous scanning failure in case of MLO

[Aditya Kumar Singh]

Currently only 1 scan can be performed on per phy level at a time in
driver. Due to this, if via other underlying phy, a scan request is sent,
kernel returns -EBUSY. And then hostapd would try to set the interface in
station mode if it was originally in AP mode and retry sending a scan
request. However, this behaviour is expected in case of multi link
operation and hence there is no need to switch the mode as such.

Hence, add logic to not change the NL mode if kernel returns -EBUSY during
multi link AP operation. The caller can accordingly decide and if needed,
it can re-schedule a scan request after some time.

Signed-off-by: Aditya Kumar Singh <quic_adisi at quicinc.com>
---
 src/drivers/driver_nl80211_scan.c | 34 +++++++++++++++++++++++++++++++
 1 file changed, 34 insertions(+)

diff --git a/src/drivers/driver_nl80211_scan.c b/src/drivers/driver_nl80211_scan.c
index 14cb324d0331..7d4efed5ca6e 100644
--- a/src/drivers/driver_nl80211_scan.c
+++ b/src/drivers/driver_nl80211_scan.c
@@ -418,6 +418,40 @@ int wpa_driver_nl80211_scan(struct i802_bss *bss,
 		if (drv->hostapd && is_ap_interface(drv->nlmode)) {
 			enum nl80211_iftype old_mode = drv->nlmode;
 
+#ifdef CONFIG_IEEE80211BE
+			/* For Multi Link BSS, retry scan if any other links
+			 * are busy scanning
+			 */
+			if (ret == -EBUSY &&
+			    nl80211_link_valid(bss->valid_links, params->link_id)) {
+				struct i802_bss *link_bss;
+				u8 link_id;
+
+				wpa_printf(MSG_DEBUG,
+					   "nl80211: Scan trigger on Multi Link BSS failed (requested link=%d on interface %s)",
+					   params->link_id, bss->ifname);
+
+				for (link_bss = drv->first_bss; link_bss;
+				     link_bss = link_bss->next)
+					if (link_bss->scan_link)
+						break;
+
+				if (!link_bss) {
+					wpa_printf(MSG_DEBUG,
+						   "nl80211: BSS information already running scan not available");
+					goto fail;
+				}
+
+				link_id =
+				       nl80211_get_link_id_from_link(link_bss,
+								     link_bss->scan_link);
+				wpa_printf(MSG_DEBUG,
+					   "nl80211: Scan already running on interface %s link %d",
+					   link_bss->ifname, link_id);
+				goto fail;
+			}
+#endif /* CONFIG_IEEE80211BE */
+
 			/*
 			 * mac80211 does not allow scan requests in AP mode, so
 			 * try to do this in station mode.
-- 
2.34.1