[PATCH RFC 3/7] net: add NAPI api to register and retrieve the page pool ptr

[Yunsheng Lin]

As tx recycling is built upon the busy polling infrastructure,
and busy polling is based on napi_id, so add a api for driver
to register a page pool to a NAPI instance and api for socket
layer to retrieve the page pool corresponding to a NAPI.

Signed-off-by: Yunsheng Lin <linyunsheng@xxxxxxxxxx>
---
 include/linux/netdevice.h |  9 +++++++++
 net/core/dev.c            | 34 +++++++++++++++++++++++++++++++---
 2 files changed, 40 insertions(+), 3 deletions(-)

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 2f03cd9..51a1169 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -40,6 +40,7 @@
 #endif
 #include <net/netprio_cgroup.h>
 #include <net/xdp.h>
+#include <net/page_pool.h>
 
 #include <linux/netdev_features.h>
 #include <linux/neighbour.h>
@@ -336,6 +337,7 @@ struct napi_struct {
 	struct hlist_node	napi_hash_node;
 	unsigned int		napi_id;
 	struct task_struct	*thread;
+	struct page_pool        *pp;
 };
 
 enum {
@@ -349,6 +351,7 @@ enum {
 	NAPI_STATE_PREFER_BUSY_POLL,	/* prefer busy-polling over softirq processing*/
 	NAPI_STATE_THREADED,		/* The poll is performed inside its own thread*/
 	NAPI_STATE_SCHED_THREADED,	/* Napi is currently scheduled in threaded mode */
+	NAPI_STATE_RECYCLABLE,          /* Support tx page recycling */
 };
 
 enum {
@@ -362,6 +365,7 @@ enum {
 	NAPIF_STATE_PREFER_BUSY_POLL	= BIT(NAPI_STATE_PREFER_BUSY_POLL),
 	NAPIF_STATE_THREADED		= BIT(NAPI_STATE_THREADED),
 	NAPIF_STATE_SCHED_THREADED	= BIT(NAPI_STATE_SCHED_THREADED),
+	NAPIF_STATE_RECYCLABLE          = BIT(NAPI_STATE_RECYCLABLE),
 };
 
 enum gro_result {
@@ -2473,6 +2477,10 @@ static inline void *netdev_priv(const struct net_device *dev)
 void netif_napi_add(struct net_device *dev, struct napi_struct *napi,
 		    int (*poll)(struct napi_struct *, int), int weight);
 
+void netif_recyclable_napi_add(struct net_device *dev, struct napi_struct *napi,
+			       int (*poll)(struct napi_struct *, int),
+			       int weight, struct page_pool *pool);
+
 /**
  *	netif_tx_napi_add - initialize a NAPI context
  *	@dev:  network device
@@ -2997,6 +3005,7 @@ struct net_device *dev_get_by_index(struct net *net, int ifindex);
 struct net_device *__dev_get_by_index(struct net *net, int ifindex);
 struct net_device *dev_get_by_index_rcu(struct net *net, int ifindex);
 struct net_device *dev_get_by_napi_id(unsigned int napi_id);
+struct page_pool *page_pool_get_by_napi_id(unsigned int napi_id);
 int netdev_get_name(struct net *net, char *name, int ifindex);
 int dev_restart(struct net_device *dev);
 int skb_gro_receive(struct sk_buff *p, struct sk_buff *skb);
diff --git a/net/core/dev.c b/net/core/dev.c
index 74fd402..d6b905b 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -935,6 +935,19 @@ struct net_device *dev_get_by_napi_id(unsigned int napi_id)
 }
 EXPORT_SYMBOL(dev_get_by_napi_id);
 
+struct page_pool *page_pool_get_by_napi_id(unsigned int napi_id)
+{
+	struct napi_struct *napi;
+	struct page_pool *pp = NULL;
+
+	napi = napi_by_id(napi_id);
+	if (napi)
+		pp = napi->pp;
+
+	return pp;
+}
+EXPORT_SYMBOL(page_pool_get_by_napi_id);
+
 /**
  *	netdev_get_name - get a netdevice name, knowing its ifindex.
  *	@net: network namespace
@@ -6757,7 +6770,8 @@ EXPORT_SYMBOL(napi_busy_loop);
 
 static void napi_hash_add(struct napi_struct *napi)
 {
-	if (test_bit(NAPI_STATE_NO_BUSY_POLL, &napi->state))
+	if (test_bit(NAPI_STATE_NO_BUSY_POLL, &napi->state) ||
+	    !test_bit(NAPI_STATE_RECYCLABLE, &napi->state))
 		return;
 
 	spin_lock(&napi_hash_lock);
@@ -6860,8 +6874,10 @@ int dev_set_threaded(struct net_device *dev, bool threaded)
 }
 EXPORT_SYMBOL(dev_set_threaded);
 
-void netif_napi_add(struct net_device *dev, struct napi_struct *napi,
-		    int (*poll)(struct napi_struct *, int), int weight)
+void netif_recyclable_napi_add(struct net_device *dev,
+			       struct napi_struct *napi,
+			       int (*poll)(struct napi_struct *, int),
+			       int weight, struct page_pool *pool)
 {
 	if (WARN_ON(test_and_set_bit(NAPI_STATE_LISTED, &napi->state)))
 		return;
@@ -6886,6 +6902,11 @@ void netif_napi_add(struct net_device *dev, struct napi_struct *napi,
 	set_bit(NAPI_STATE_SCHED, &napi->state);
 	set_bit(NAPI_STATE_NPSVC, &napi->state);
 	list_add_rcu(&napi->dev_list, &dev->napi_list);
+	if (pool) {
+		napi->pp = pool;
+		set_bit(NAPI_STATE_RECYCLABLE, &napi->state);
+	}
+
 	napi_hash_add(napi);
 	/* Create kthread for this napi if dev->threaded is set.
 	 * Clear dev->threaded if kthread creation failed so that
@@ -6894,6 +6915,13 @@ void netif_napi_add(struct net_device *dev, struct napi_struct *napi,
 	if (dev->threaded && napi_kthread_create(napi))
 		dev->threaded = 0;
 }
+EXPORT_SYMBOL(netif_recyclable_napi_add);
+
+void netif_napi_add(struct net_device *dev, struct napi_struct *napi,
+		    int (*poll)(struct napi_struct *, int), int weight)
+{
+	netif_recyclable_napi_add(dev, napi, poll, weight, NULL);
+}
 EXPORT_SYMBOL(netif_napi_add);
 
 void napi_disable(struct napi_struct *n)
-- 
2.7.4