igb: Introduce multiple TX queues with infrastructure

This code adds multiple Tx queue infrastructure much like we
previously did in ixgbe. The MSI-X vector mapping is the bulk of
the change.

IAM can now be safely enabled and we've verified that it does
work correctly. We can also eliminate the tx ring lock.
Signed-off-by: Peter P Waskiewicz Jr <peter.p.waskiewicz.jr@intel.com>
Signed-off-by: Mitch Williams <mitch.a.williams@intel.com>
Signed-off-by: Auke Kok <auke-jan.h.kok@intel.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

drivers/net/igb/igb.h

@@ -62,6 +62,7 @@ struct igb_adapter;
 
 /* Transmit and receive queues */
 #define IGB_MAX_RX_QUEUES                  4
+#define IGB_MAX_TX_QUEUES                  4
 
 /* RX descriptor control thresholds.
  * PTHRESH - MAC will consider prefetch if it has fewer than this number of
@@ -157,8 +158,6 @@ struct igb_ring {
 	union {
 		/* TX */
 		struct {
-			spinlock_t tx_clean_lock;
-			spinlock_t tx_lock;
 			bool detect_tx_hung;
 		};
 		/* RX */
@@ -277,6 +276,10 @@ struct igb_adapter {
 	/* for ioport free */
 	int bars;
 	int need_ioport;
+
+#ifdef CONFIG_NETDEVICES_MULTIQUEUE
+	struct igb_ring *multi_tx_table[IGB_MAX_TX_QUEUES];
+#endif /* CONFIG_NETDEVICES_MULTIQUEUE */
 };
 
 enum e1000_state_t {