Net pgrants

drivers/net/xen-netback/common.h

@@ -132,6 +132,14 @@ struct xenvif_copy_state {
 	struct sk_buff_head *completed;
 };
 
+struct persistent_gnt {
+	struct page *page;
+	grant_ref_t gnt;
+	grant_handle_t handle;
+	bool active;
+	struct rb_node node;
+};
+
 struct xenvif_queue { /* Per-queue data for xenvif */
 	unsigned int id; /* Queue ID, 0-based */
 	char name[QUEUE_NAME_SIZE]; /* DEVNAME-qN */
@@ -213,6 +221,12 @@ struct xenvif_queue { /* Per-queue data for xenvif */
 	u64 credit_window_start;
 	bool rate_limited;
 
+	/* Persistent grants */
+	struct rb_root	persistent_gnts;
+	unsigned int	persistent_gnt_c;
+	struct gnttab_page_cache persistent_pages;
+	struct persistent_gnt *tx_pgrants[MAX_PENDING_REQS];
+
 	/* Statistics */
 	struct xenvif_stats stats;
 };
@@ -291,6 +305,7 @@ struct xenvif {
 	u8 can_sg:1;
 	u8 ip_csum:1;
 	u8 ipv6_csum:1;
+	u8 persistent_grants:1;
 	u8 multicast_control:1;
 
 	/* headroom requested by xen-netfront */
@@ -408,6 +423,7 @@ extern bool provides_xdp_headroom;
 extern unsigned int rx_drain_timeout_msecs;
 extern unsigned int rx_stall_timeout_msecs;
 extern unsigned int xenvif_max_queues;
+extern unsigned int xenvif_max_pgrants;
 extern unsigned int xenvif_hash_cache_size;
 
 #ifdef CONFIG_DEBUG_FS
@@ -416,12 +432,16 @@ extern struct dentry *xen_netback_dbg_root;
 
 void xenvif_skb_zerocopy_prepare(struct xenvif_queue *queue,
 				 struct sk_buff *skb);
-void xenvif_skb_zerocopy_complete(struct xenvif_queue *queue);
+void xenvif_skb_zerocopy_complete(struct xenvif_queue *queue,
+				 unsigned int pending_dealloc);
 
 /* Multicast control */
 bool xenvif_mcast_match(struct xenvif *vif, const u8 *addr);
 void xenvif_mcast_addr_list_free(struct xenvif *vif);
 
+/* Persistent grants */
+void xenvif_pgrants_destroy(struct xenvif_queue *queue);
+
 /* Hash */
 void xenvif_init_hash(struct xenvif *vif);
 void xenvif_deinit_hash(struct xenvif *vif);

drivers/net/xen-netback/interface.c

@@ -56,15 +56,17 @@ void xenvif_skb_zerocopy_prepare(struct xenvif_queue *queue,
 	atomic_inc(&queue->inflight_packets);
 }
 
-void xenvif_skb_zerocopy_complete(struct xenvif_queue *queue)
+void xenvif_skb_zerocopy_complete(struct xenvif_queue *queue,
+				unsigned int pending_dealloc)
 {
 	atomic_dec(&queue->inflight_packets);
 
 	/* Wake the dealloc thread _after_ decrementing inflight_packets so
 	 * that if kthread_stop() has already been called, the dealloc thread
 	 * does not wait forever with nothing to wake it.
 	 */
-	wake_up(&queue->dealloc_wq);
+	if (pending_dealloc)
+		wake_up(&queue->dealloc_wq);
 }
 
 static int xenvif_schedulable(struct xenvif *vif)
@@ -588,12 +590,18 @@ int xenvif_init_queue(struct xenvif_queue *queue)
 		return -ENOMEM;
 	}
 
+	if (queue->vif->persistent_grants) {
+		queue->persistent_gnts.rb_node = NULL;
+		queue->persistent_gnt_c = 0;
+	}
+
 	for (i = 0; i < MAX_PENDING_REQS; i++) {
 		queue->pending_tx_info[i].callback_struct = (struct ubuf_info_msgzc)
 			{ { .callback = xenvif_zerocopy_callback },
 			  { { .ctx = NULL,
 			      .desc = i } } };
 		queue->grant_tx_handle[i] = NETBACK_INVALID_HANDLE;
+		queue->tx_pgrants[i] = NULL;
 	}
 
 	return 0;
@@ -696,6 +704,10 @@ static void xenvif_disconnect_queue(struct xenvif_queue *queue)
 	}
 
 	xenvif_unmap_frontend_data_rings(queue);
+
+	if (queue->vif->persistent_grants) {
+		xenvif_pgrants_destroy(queue);
+	}
 }
 
 int xenvif_connect_data(struct xenvif_queue *queue,