skbuff: remove __kfree_skb_flush()

This function isn't much needed as NAPI skb queue gets bulk-freed
anyway when there's no more room, and even may reduce the efficiency
of bulk operations.
It will be even less needed after reusing skb cache on allocation path,
so remove it and this way lighten network softirqs a bit.

Suggested-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Alexander Lobakin <alobakin@pm.me>

include/linux/skbuff.h

@@ -2919,7 +2919,6 @@ static inline struct sk_buff *napi_alloc_skb(struct napi_struct *napi,
 }
 void napi_consume_skb(struct sk_buff *skb, int budget);
 
-void __kfree_skb_flush(void);
 void __kfree_skb_defer(struct sk_buff *skb);
 
 /**

net/core/dev.c

@@ -4944,8 +4944,6 @@ static __latent_entropy void net_tx_action(struct softirq_action *h)
 			else
 				__kfree_skb_defer(skb);
 		}
-
-		__kfree_skb_flush();
 	}
 
 	if (sd->output_queue) {
@@ -7041,7 +7039,7 @@ static __latent_entropy void net_rx_action(struct softirq_action *h)
 
 		if (list_empty(&list)) {
 			if (!sd_has_rps_ipi_waiting(sd) && list_empty(&repoll))
-				goto out;
+				return;
 			break;
 		}
 
@@ -7068,8 +7066,6 @@ static __latent_entropy void net_rx_action(struct softirq_action *h)
 		__raise_softirq_irqoff(NET_RX_SOFTIRQ);
 
 	net_rps_action_and_irq_enable(sd);
-out:
-	__kfree_skb_flush();
 }
 
 struct netdev_adjacent {

net/core/skbuff.c

@@ -838,18 +838,6 @@ void __consume_stateless_skb(struct sk_buff *skb)
 	kfree_skbmem(skb);
 }
 
-void __kfree_skb_flush(void)
-{
-	struct napi_alloc_cache *nc = this_cpu_ptr(&napi_alloc_cache);
-
-	/* flush skb_cache if containing objects */
-	if (nc->skb_count) {
-		kmem_cache_free_bulk(skbuff_head_cache, nc->skb_count,
-				     nc->skb_cache);
-		nc->skb_count = 0;
-	}
-}
-
 static inline void _kfree_skb_defer(struct sk_buff *skb)
 {
 	struct napi_alloc_cache *nc = this_cpu_ptr(&napi_alloc_cache);