hsr: fix don't prune the master node from the node_db

Don't prune the master node in the hsr_prune_nodes function.
Neither time_in[HSR_PT_SLAVE_A] nor time_in[HSR_PT_SLAVE_B]
will ever be updated by hsr_register_frame_in for the master port.
Thus, the master node will be repeatedly pruned leading to
repeated packet loss.
This bug never appeared because the hsr_prune_nodes function
was only called once. Since commit 5150b45f
("net: hsr: Fix node prune function for forget time expiry") this issue
is fixed unveiling the issue described above.

Fixes: 5150b45f ("net: hsr: Fix node prune function for forget time expiry")
Signed-off-by: Andreas Oetken <andreas.oetken@siemens.com>
Tested-by: Murali Karicheri <m-karicheri2@ti.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/hsr/hsr_framereg.c

@@ -365,6 +365,14 @@ void hsr_prune_nodes(struct timer_list *t)
 
 	rcu_read_lock();
 	list_for_each_entry_rcu(node, &hsr->node_db, mac_list) {
+		/* Don't prune own node. Neither time_in[HSR_PT_SLAVE_A]
+		 * nor time_in[HSR_PT_SLAVE_B], will ever be updated for
+		 * the master port. Thus the master node will be repeatedly
+		 * pruned leading to packet loss.
+		 */
+		if (hsr_addr_is_self(hsr, node->macaddress_A))
+			continue;
+
 		/* Shorthand */
 		time_a = node->time_in[HSR_PT_SLAVE_A];
 		time_b = node->time_in[HSR_PT_SLAVE_B];