net/sfc: fix MAC stats lock in xstats query by ID

[ upstream commit 9076e85 ]

Add MAC stats lock in xstats_get_by_id() callback before reading
number of supported MAC stats.

Fixes: 73280c1 ("net/sfc: support xstats retrieval by ID")

Signed-off-by: Ivan Ilchenko <ivan.ilchenko@oktetlabs.ru>
Signed-off-by: Andrew Rybchenko <andrew.rybchenko@oktetlabs.ru>
Reviewed-by: Andy Moreton <amoreton@xilinx.com>

drivers/net/sfc/sfc_ethdev.c

@@ -772,12 +772,14 @@ sfc_xstats_get_by_id(struct rte_eth_dev *dev, const uint64_t *ids,
 	int ret;
 	int rc;
 
-	if (unlikely(values == NULL) ||
-	    unlikely((ids == NULL) && (n < port->mac_stats_nb_supported)))
-		return port->mac_stats_nb_supported;
-
 	rte_spinlock_lock(&port->mac_stats_lock);
 
+	if (unlikely(values == NULL) ||
+	    unlikely(ids == NULL && n < port->mac_stats_nb_supported)) {
+		ret = port->mac_stats_nb_supported;
+		goto unlock;
+	}
+
 	rc = sfc_port_update_mac_stats(sa);
 	if (rc != 0) {
 		SFC_ASSERT(rc > 0);