mac80211: use RCU_INIT_POINTER

rcu_assign_pointer() ensures that the initialization of a structure is
carried out before storing a pointer to that structure. However, in the
case that NULL is assigned there's no structure to initialize so using
RCU_INIT_POINTER instead is safe and more efficient.

Signed-off-by: Monam Agarwal <monamagarwal123@gmail.com>
[squash eight tiny patches, rewrite commit log]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
diff --git a/net/mac80211/scan.c b/net/mac80211/scan.c
index 3ce7f2c..28185c8 100644
--- a/net/mac80211/scan.c
+++ b/net/mac80211/scan.c
@@ -309,7 +309,7 @@
 	if (local->scan_req != local->int_scan_req)
 		cfg80211_scan_done(local->scan_req, aborted);
 	local->scan_req = NULL;
-	rcu_assign_pointer(local->scan_sdata, NULL);
+	RCU_INIT_POINTER(local->scan_sdata, NULL);
 
 	local->scanning = 0;
 	local->scan_chandef.chan = NULL;
@@ -559,7 +559,7 @@
 		ieee80211_recalc_idle(local);
 
 		local->scan_req = NULL;
-		rcu_assign_pointer(local->scan_sdata, NULL);
+		RCU_INIT_POINTER(local->scan_sdata, NULL);
 	}
 
 	return rc;
@@ -773,7 +773,7 @@
 		int rc;
 
 		local->scan_req = NULL;
-		rcu_assign_pointer(local->scan_sdata, NULL);
+		RCU_INIT_POINTER(local->scan_sdata, NULL);
 
 		rc = __ieee80211_start_scan(sdata, req);
 		if (rc) {
@@ -1014,7 +1014,7 @@
 
 	if (ret) {
 		/* Clean in case of failure after HW restart or upon resume. */
-		rcu_assign_pointer(local->sched_scan_sdata, NULL);
+		RCU_INIT_POINTER(local->sched_scan_sdata, NULL);
 		local->sched_scan_req = NULL;
 	}
 
@@ -1089,7 +1089,7 @@
 		return;
 	}
 
-	rcu_assign_pointer(local->sched_scan_sdata, NULL);
+	RCU_INIT_POINTER(local->sched_scan_sdata, NULL);
 
 	/* If sched scan was aborted by the driver. */
 	local->sched_scan_req = NULL;