[RFC/RFT v2 1/3] net: Add napi_init_for_gro routine

[Lorenzo Bianconi <lorenzo@xxxxxxxxxx>]

Introduce napi_init_for_gro utility routine to initialize napi_struct
for GRO. This is a preliminary patch to introduce GRO support to cpumap
codebase.

Signed-off-by: Lorenzo Bianconi <lorenzo@xxxxxxxxxx>
---
 include/linux/netdevice.h |  2 ++
 net/core/dev.c            | 23 +++++++++++++++++------
 2 files changed, 19 insertions(+), 6 deletions(-)

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 607009150b5fa..3c4c3ae2170f0 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -2628,6 +2628,8 @@ static inline void netif_napi_set_irq(struct napi_struct *napi, int irq)
  */
 #define NAPI_POLL_WEIGHT 64
 
+int napi_init_for_gro(struct net_device *dev, struct napi_struct *napi,
+		      int (*poll)(struct napi_struct *, int), int weight);
 void netif_napi_add_weight(struct net_device *dev, struct napi_struct *napi,
 			   int (*poll)(struct napi_struct *, int), int weight);
 
diff --git a/net/core/dev.c b/net/core/dev.c
index f66e614078832..c87c510abc05b 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -6638,13 +6638,14 @@ void netif_queue_set_napi(struct net_device *dev, unsigned int queue_index,
 }
 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)
+int napi_init_for_gro(struct net_device *dev, struct napi_struct *napi,
+		      int (*poll)(struct napi_struct *, int), int weight)
 {
 	if (WARN_ON(test_and_set_bit(NAPI_STATE_LISTED, &napi->state)))
-		return;
+		return -EBUSY;
 
 	INIT_LIST_HEAD(&napi->poll_list);
+	INIT_LIST_HEAD(&napi->dev_list);
 	INIT_HLIST_NODE(&napi->napi_hash_node);
 	hrtimer_init(&napi->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_PINNED);
 	napi->timer.function = napi_watchdog;
@@ -6662,18 +6663,28 @@ void netif_napi_add_weight(struct net_device *dev, struct napi_struct *napi,
 	napi->poll_owner = -1;
 #endif
 	napi->list_owner = -1;
+	napi_hash_add(napi);
+	napi_get_frags_check(napi);
+	netif_napi_set_irq(napi, -1);
+
+	return 0;
+}
+
+void netif_napi_add_weight(struct net_device *dev, struct napi_struct *napi,
+			   int (*poll)(struct napi_struct *, int), int weight)
+{
+	if (napi_init_for_gro(dev, napi, poll, weight))
+		return;
+
 	set_bit(NAPI_STATE_SCHED, &napi->state);
 	set_bit(NAPI_STATE_NPSVC, &napi->state);
 	list_add_rcu(&napi->dev_list, &dev->napi_list);
-	napi_hash_add(napi);
-	napi_get_frags_check(napi);
 	/* Create kthread for this napi if dev->threaded is set.
 	 * Clear dev->threaded if kthread creation failed so that
 	 * threaded mode will not be enabled in napi_enable().
 	 */
 	if (dev->threaded && napi_kthread_create(napi))
 		dev->threaded = false;
-	netif_napi_set_irq(napi, -1);
 }
 EXPORT_SYMBOL(netif_napi_add_weight);
 
-- 
2.46.0