Fix for apps watchdog detected while changing wifi frequecy band
if the time between band update and scan done callback is very
small then band change will not reflect in SME and SME reports
to HDD all the channels correponding to previous band.This is
due to race condition.but those channels are invalid to the new
band and so the function __ieee80211_get_channel will return
NULL.Each time we report scan result with this pointer null
warning kernel trace is printed.If the scan results contain
large number of APs continuosly kernel warning trace is printed
and it will lead to apps watch dog bark.So drop the bss and
continue to next bss.
Change-Id: Ie7de62d2e2d66b037d9cee7a3889ff3c997ee330
CRs-fixed: 440105
diff --git a/CORE/HDD/src/wlan_hdd_cfg80211.c b/CORE/HDD/src/wlan_hdd_cfg80211.c
old mode 100644
new mode 100755
index 31b3dd6..252a89b
--- a/CORE/HDD/src/wlan_hdd_cfg80211.c
+++ b/CORE/HDD/src/wlan_hdd_cfg80211.c
@@ -3639,7 +3639,23 @@
freq = ieee80211_channel_to_frequency(chan_no);
#endif
chan = __ieee80211_get_channel(wiphy, freq);
-
+ /*when the band is changed on the fly using the GUI, three things are done
+ * 1. scan abort 2.flush scan results from cache 3.update the band with the new band user specified(refer to the hdd_setBand_helper function)
+ * as part of the scan abort, message willbe queued to PE and we proceed with flushing and changinh the band.
+ * pe will stop the scanning further and report back the results what ever it had till now by calling the call back function.
+ * if the time between update band and scandone call back is sufficent enough the band change reflects in SME, SME validates the channels
+ * and discards the channels correponding to previous band and calls back with zero bss results.
+ * but if the time between band update and scan done callback is very small then band change will not reflect in SME and SME reports to HDD
+ * all the channels correponding to previous band.this is due to race condition.but those channels are invalid to the new band and so
+ * this function __ieee80211_get_channel will return NULL.Each time we report scan result with this pointer null warning kernel trace is printed.
+ * if the scan results contain large number of APs continuosly kernel warning trace is printed and it will lead to apps watch dog bark.
+ * So drop the bss and continue to next bss.
+ */
+ if(chan == NULL)
+ {
+ hddLog(VOS_TRACE_LEVEL_INFO, "%s chan pointer is NULL", __func__);
+ return NULL;
+ }
/*To keep the rssi icon of the connected AP in the scan window
*and the rssi icon of the wireless networks in sync
* */