qcacld-3.0: Print drv ops inactive thread call stack

As part of the wlan driver handlers for kernel ndo events, an inactivity
timer (effectively a watchdog timer) is started. This allows us to catch
instances where drvier operations take much longer than expected. In
cases where this inactivity timer expires, print the stack trace of the
inactive thread to expedite debugging efforts.

Change-Id: I4427207a5cd7d232486ce453555765f7e0f4fe17
CRs-Fixed: 2160837

core/hdd/src/wlan_hdd_main.c

@@ -183,6 +183,7 @@ static struct attribute *attrs[] = {
 #define MAX_OPS_NAME_STRING_SIZE 20
 
 static qdf_timer_t hdd_drv_ops_inactivity_timer;
+static struct task_struct *hdd_drv_ops_task;
 static char drv_ops_string[MAX_OPS_NAME_STRING_SIZE];
 
 /* the Android framework expects this param even though we don't use it */
@@ -13215,6 +13216,7 @@ void hdd_start_driver_ops_timer(int drv_op)
 		break;
 	}
 
+	hdd_drv_ops_task = current;
 	qdf_timer_start(&hdd_drv_ops_inactivity_timer,
 		HDD_OPS_INACTIVITY_TIMEOUT);
 }
@@ -13240,6 +13242,13 @@ void hdd_drv_ops_inactivity_handler(void)
 	hdd_err("%s: %d Sec timer expired while in .%s",
 		__func__, HDD_OPS_INACTIVITY_TIMEOUT/1000, drv_ops_string);
 
+	if (hdd_drv_ops_task) {
+		printk("Call stack for \"%s\"\n", hdd_drv_ops_task->comm);
+		qdf_print_thread_trace(hdd_drv_ops_task);
+	} else {
+		hdd_err("hdd_drv_ops_task is null");
+	}
+
 	/* Driver shutdown is stuck, no recovery possible at this point */
 	if (0 == qdf_mem_cmp(&drv_ops_string[0], "shutdown",
 		sizeof("shutdown")))