mac80211: Move ieee80211_mgd_auth() EBUSY check to be before allocation

This makes it easier to conditionally replace full allocation of
auth_data to use reallocation for the case of continuing SAE
authentication. Furthermore, there was not really any point in having
this check done so late in the function after having already completed
number of steps that cannot be used anyway in the error case.
Signed-off-by: Jouni Malinen <jouni@codeaurora.org>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/mlme.c

@@ -4922,6 +4922,10 @@ int ieee80211_mgd_auth(struct ieee80211_sub_if_data *sdata,
 		return -EOPNOTSUPP;
 	}
 
+	if ((ifmgd->auth_data && !ifmgd->auth_data->done) ||
+	    ifmgd->assoc_data)
+		return -EBUSY;
+
 	auth_data = kzalloc(sizeof(*auth_data) + req->auth_data_len +
 			    req->ie_len, GFP_KERNEL);
 	if (!auth_data)
@@ -4957,12 +4961,6 @@ int ieee80211_mgd_auth(struct ieee80211_sub_if_data *sdata,
 
 	/* try to authenticate/probe */
 
-	if ((ifmgd->auth_data && !ifmgd->auth_data->done) ||
-	    ifmgd->assoc_data) {
-		err = -EBUSY;
-		goto err_free;
-	}
-
 	if (ifmgd->auth_data)
 		ieee80211_destroy_auth_data(sdata, false);
 
@@ -5007,7 +5005,6 @@ int ieee80211_mgd_auth(struct ieee80211_sub_if_data *sdata,
 	mutex_lock(&sdata->local->mtx);
 	ieee80211_vif_release_channel(sdata);
 	mutex_unlock(&sdata->local->mtx);
- err_free:
 	kfree(auth_data);
 	return err;
 }