net: Add queue and napi association

Add the napi pointer in netdev queue for tracking the napi
instance for each queue. This achieves the queue<->napi mapping.
Signed-off-by: Amritha Nambiar <amritha.nambiar@intel.com>
Reviewed-by: Sridhar Samudrala <sridhar.samudrala@intel.com>
Link: https://lore.kernel.org/r/170147331483.5260.15723438819994285695.stgit@anambiarhost.jf.intel.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

include/linux/netdevice.h

@@ -665,6 +665,10 @@ struct netdev_queue {
 #ifdef CONFIG_XDP_SOCKETS
 	struct xsk_buff_pool    *pool;
 #endif
+	/* NAPI instance for the queue
+	 * Readers and writers must hold RTNL
+	 */
+	struct napi_struct      *napi;
 /*
  * write-mostly part
  */
@@ -2657,6 +2661,10 @@ static inline void *netdev_priv(const struct net_device *dev)
  */
 #define SET_NETDEV_DEVTYPE(net, devtype)	((net)->dev.type = (devtype))
 
+void netif_queue_set_napi(struct net_device *dev, unsigned int queue_index,
+			  enum netdev_queue_type type,
+			  struct napi_struct *napi);
+
 /* Default NAPI poll() weight
  * Device drivers are strongly advised to not use bigger value
  */

include/net/netdev_rx_queue.h

@@ -21,6 +21,10 @@ struct netdev_rx_queue {
 #ifdef CONFIG_XDP_SOCKETS
 	struct xsk_buff_pool            *pool;
 #endif
+	/* NAPI instance for the queue
+	 * Readers and writers must hold RTNL
+	 */
+	struct napi_struct		*napi;
 } ____cacheline_aligned_in_smp;
 
 /*

net/core/dev.c

@@ -6400,6 +6400,43 @@ int dev_set_threaded(struct net_device *dev, bool threaded)
 }
 EXPORT_SYMBOL(dev_set_threaded);
 
+/**
+ * netif_queue_set_napi - Associate queue with the napi
+ * @dev: device to which NAPI and queue belong
+ * @queue_index: Index of queue
+ * @type: queue type as RX or TX
+ * @napi: NAPI context, pass NULL to clear previously set NAPI
+ *
+ * Set queue with its corresponding napi context. This should be done after
+ * registering the NAPI handler for the queue-vector and the queues have been
+ * mapped to the corresponding interrupt vector.
+ */
+void netif_queue_set_napi(struct net_device *dev, unsigned int queue_index,
+			  enum netdev_queue_type type, struct napi_struct *napi)
+{
+	struct netdev_rx_queue *rxq;
+	struct netdev_queue *txq;
+
+	if (WARN_ON_ONCE(napi && !napi->dev))
+		return;
+	if (dev->reg_state >= NETREG_REGISTERED)
+		ASSERT_RTNL();
+
+	switch (type) {
+	case NETDEV_QUEUE_TYPE_RX:
+		rxq = __netif_get_rx_queue(dev, queue_index);
+		rxq->napi = napi;
+		return;
+	case NETDEV_QUEUE_TYPE_TX:
+		txq = netdev_get_tx_queue(dev, queue_index);
+		txq->napi = napi;
+		return;
+	default:
+		return;
+	}
+}
+EXPORT_SYMBOL(netif_queue_set_napi);
+
 void netif_napi_add_weight(struct net_device *dev, struct napi_struct *napi,
 			   int (*poll)(struct napi_struct *, int), int weight)
 {