net: ti: icssg-prueth: Fix race condition for VLAN table access

The VLAN table is a shared memory between the two ports/slices
in a ICSSG cluster and this may lead to race condition when the
common code paths for both ports are executed in different CPUs.

Fix the race condition access by locking the shared memory access

Fixes: 487f7323 ("net: ti: icssg-prueth: Add helper functions to configure FDB")
Signed-off-by: MD Danish Anwar <danishanwar@ti.com>
Reviewed-by: Roger Quadros <rogerq@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/ti/icssg/icssg_config.c

@@ -735,6 +735,7 @@ void icssg_vtbl_modify(struct prueth_emac *emac, u8 vid, u8 port_mask,
 	u8 fid_c1;
 
 	tbl = prueth->vlan_tbl;
+	spin_lock(&prueth->vtbl_lock);
 	fid_c1 = tbl[vid].fid_c1;
 
 	/* FID_C1: bit0..2 port membership mask,
@@ -750,6 +751,7 @@ void icssg_vtbl_modify(struct prueth_emac *emac, u8 vid, u8 port_mask,
 	}
 
 	tbl[vid].fid_c1 = fid_c1;
+	spin_unlock(&prueth->vtbl_lock);
 }
 EXPORT_SYMBOL_GPL(icssg_vtbl_modify);
 

drivers/net/ethernet/ti/icssg/icssg_prueth.c

@@ -1442,6 +1442,7 @@ static int prueth_probe(struct platform_device *pdev)
 		icss_iep_init_fw(prueth->iep1);
 	}
 
+	spin_lock_init(&prueth->vtbl_lock);
 	/* setup netdev interfaces */
 	if (eth0_node) {
 		ret = prueth_netdev_init(prueth, eth0_node);

drivers/net/ethernet/ti/icssg/icssg_prueth.h

@@ -296,6 +296,8 @@ struct prueth {
 	bool is_switchmode_supported;
 	unsigned char switch_id[MAX_PHYS_ITEM_ID_LEN];
 	int default_vlan;
+	/** @vtbl_lock: Lock for vtbl in shared memory */
+	spinlock_t vtbl_lock;
 };
 
 struct emac_tx_ts_response {