staging: lustre: fix 'data race condition' issue in conrpc.c

Fix 'data race condition' defects found by Coverity version 6.5.0:
Data race condition (MISSING_LOCK)
Accessing variable without holding lock. Elsewhere,
this variable is accessed with lock held.

Signed-off-by: Sebastien Buisson <sbuisson@ddn.com>
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-2744
Reviewed-on: http://review.whamcloud.com/6567
Reviewed-by: Liang Zhen <liang.zhen@intel.com>
Reviewed-by: Dmitry Eremin <dmitry.eremin@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/lustre/lnet/selftest/conrpc.c

@@ -945,8 +945,12 @@ lstcon_sesnew_stat_reply(lstcon_rpc_trans_t *trans,
 		return status;
 
 	if (!trans->tas_feats_updated) {
-		trans->tas_feats_updated = 1;
-		trans->tas_features = reply->msg_ses_feats;
+		spin_lock(&console_session.ses_rpc_lock);
+		if (!trans->tas_feats_updated) { /* recheck with lock */
+			trans->tas_feats_updated = 1;
+			trans->tas_features = reply->msg_ses_feats;
+		}
+		spin_unlock(&console_session.ses_rpc_lock);
 	}
 
 	if (reply->msg_ses_feats != trans->tas_features) {