[vlan] Provide vlan_can_be_trunk()

Signed-off-by: Michael Brown <mcb30@ipxe.org>

diff --git a/src/include/ipxe/vlan.h b/src/include/ipxe/vlan.h
index 86d78bed0e929a65eb43bea628ab4a776b6d678f..b4d06b87c0c8c6579642001bc0565ac01022c0f9 100644 (file)
--- a/src/include/ipxe/vlan.h
+++ b/src/include/ipxe/vlan.h
@@ -59,6 +59,7 @@ struct vlan_header {
  */
 #define VLAN_PRIORITY_IS_VALID( priority ) ( (priority) <= 7 )
 
+extern int vlan_can_be_trunk ( struct net_device *trunk );
 extern int vlan_create ( struct net_device *trunk, unsigned int tag,
                         unsigned int priority );
 extern int vlan_destroy ( struct net_device *netdev );

diff --git a/src/net/vlan.c b/src/net/vlan.c
index f0479e0ff07d701c0d00cac493baf114c64b4e51..b16c6934bac1ac94bf72778f24f5015eed2451ba 100644 (file)
--- a/src/net/vlan.c
+++ b/src/net/vlan.c
@@ -280,20 +280,35 @@ struct net_protocol vlan_protocol __net_protocol = {
 };
 
 /**
- * Create VLAN device
+ * Check if network device can be used as a VLAN trunk device
  *
  * @v trunk            Trunk network device
- * @v tag              VLAN tag
- * @v priority         Default VLAN priority
- * @ret rc             Return status code
+ * @ret is_ok          Trunk network device is usable
  *
- * The VLAN device will be created as an Ethernet device.  (We cannot
+ * VLAN devices will be created as Ethernet devices.  (We cannot
  * simply clone the link layer of the trunk network device, because
  * this link layer may expect the network device structure to contain
  * some link-layer-private data.)  The trunk network device must
  * therefore have a link layer that is in some sense 'compatible' with
  * Ethernet; specifically, it must have link-layer addresses that are
  * the same length as Ethernet link-layer addresses.
+ *
+ * As an additional check, and primarily to assist with the sanity of
+ * the FCoE code, we refuse to allow nested VLANs.
+ */
+int vlan_can_be_trunk ( struct net_device *trunk ) {
+
+       return ( ( trunk->ll_protocol->ll_addr_len == ETH_ALEN ) &&
+                ( trunk->op != &vlan_operations ) );
+}
+
+/**
+ * Create VLAN device
+ *
+ * @v trunk            Trunk network device
+ * @v tag              VLAN tag
+ * @v priority         Default VLAN priority
+ * @ret rc             Return status code
  */
 int vlan_create ( struct net_device *trunk, unsigned int tag,
                  unsigned int priority ) {
@@ -313,9 +328,9 @@ int vlan_create ( struct net_device *trunk, unsigned int tag,
        }
 
        /* Sanity checks */
-       if ( trunk->ll_protocol->ll_addr_len != ETH_ALEN ) {
-               DBGC ( trunk, "VLAN %s cannot create VLAN for %s device\n",
-                      trunk->name, trunk->ll_protocol->name );
+       if ( ! vlan_can_be_trunk ( trunk ) ) {
+               DBGC ( trunk, "VLAN %s cannot create VLAN on non-trunk "
+                      "device\n", trunk->name );
                rc = -ENOTTY;
                goto err_sanity;
        }