[PATCH v6 net-next 11/11] skbuff: queue NAPI_MERGED_FREE skbs into NAPI cache instead of freeing

From: Alexander Lobakin <alobakin@pm.me>
To: "David S. Miller" <davem@davemloft.net>,
	Jakub Kicinski <kuba@kernel.org>
Cc: "Jonathan Lemon" <jonathan.lemon@gmail.com>,
	"Eric Dumazet" <edumazet@google.com>,
	"Dmitry Vyukov" <dvyukov@google.com>,
	"Willem de Bruijn" <willemb@google.com>,
	"Alexander Lobakin" <alobakin@pm.me>,
	"Randy Dunlap" <rdunlap@infradead.org>,
	"Kevin Hao" <haokexin@gmail.com>,
	"Pablo Neira Ayuso" <pablo@netfilter.org>,
	"Jakub Sitnicki" <jakub@cloudflare.com>,
	"Marco Elver" <elver@google.com>,
	"Dexuan Cui" <decui@microsoft.com>,
	"Paolo Abeni" <pabeni@redhat.com>,
	"Jesper Dangaard Brouer" <brouer@redhat.com>,
	"Alexander Duyck" <alexanderduyck@fb.com>,
	"Alexander Duyck" <alexander.duyck@gmail.com>,
	"Alexei Starovoitov" <ast@kernel.org>,
	"Daniel Borkmann" <daniel@iogearbox.net>,
	"Andrii Nakryiko" <andriin@fb.com>,
	"Taehee Yoo" <ap420073@gmail.com>, "Wei Wang" <weiwan@google.com>,
	"Cong Wang" <xiyou.wangcong@gmail.com>,
	"Björn Töpel" <bjorn@kernel.org>,
	"Miaohe Lin" <linmiaohe@huawei.com>,
	"Guillaume Nault" <gnault@redhat.com>,
	"Florian Westphal" <fw@strlen.de>,
	"Edward Cree" <ecree.xilinx@gmail.com>,
	linux-kernel@vger.kernel.org, netdev@vger.kernel.org
Subject: [PATCH v6 net-next 11/11] skbuff: queue NAPI_MERGED_FREE skbs into NAPI cache instead of freeing
Date: Sat, 13 Feb 2021 14:13:09 +0000	[thread overview]
Message-ID: <20210213141021.87840-12-alobakin@pm.me> (raw)
In-Reply-To: <20210213141021.87840-1-alobakin@pm.me>

napi_frags_finish() and napi_skb_finish() can only be called inside
NAPI Rx context, so we can feed NAPI cache with skbuff_heads that
got NAPI_MERGED_FREE verdict instead of immediate freeing.
Replace __kfree_skb() with __kfree_skb_defer() in napi_skb_finish()
and move napi_skb_free_stolen_head() to skbuff.c, so it can drop skbs
to NAPI cache.
As many drivers call napi_alloc_skb()/napi_get_frags() on their
receive path, this becomes especially useful.

Signed-off-by: Alexander Lobakin <alobakin@pm.me>
---
 include/linux/skbuff.h |  1 +
 net/core/dev.c         |  9 +--------
 net/core/skbuff.c      | 12 +++++++++---
 3 files changed, 11 insertions(+), 11 deletions(-)

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 906122eac82a..6d0a33d1c0db 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -2921,6 +2921,7 @@ static inline struct sk_buff *napi_alloc_skb(struct napi_struct *napi,
 }
 void napi_consume_skb(struct sk_buff *skb, int budget);
 
+void napi_skb_free_stolen_head(struct sk_buff *skb);
 void __kfree_skb_defer(struct sk_buff *skb);
 
 /**
diff --git a/net/core/dev.c b/net/core/dev.c
index 631807c196ad..ea9b46318d23 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -6095,13 +6095,6 @@ struct packet_offload *gro_find_complete_by_type(__be16 type)
 }
 EXPORT_SYMBOL(gro_find_complete_by_type);
 
-static void napi_skb_free_stolen_head(struct sk_buff *skb)
-{
-	skb_dst_drop(skb);
-	skb_ext_put(skb);
-	kmem_cache_free(skbuff_head_cache, skb);
-}
-
 static gro_result_t napi_skb_finish(struct napi_struct *napi,
 				    struct sk_buff *skb,
 				    gro_result_t ret)
@@ -6115,7 +6108,7 @@ static gro_result_t napi_skb_finish(struct napi_struct *napi,
 		if (NAPI_GRO_CB(skb)->free == NAPI_GRO_FREE_STOLEN_HEAD)
 			napi_skb_free_stolen_head(skb);
 		else
-			__kfree_skb(skb);
+			__kfree_skb_defer(skb);
 		break;
 
 	case GRO_HELD:
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 875e1a453f7e..545a472273a5 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -916,9 +916,6 @@ static void napi_skb_cache_put(struct sk_buff *skb)
 	struct napi_alloc_cache *nc = this_cpu_ptr(&napi_alloc_cache);
 	u32 i;
 
-	/* drop skb->head and call any destructors for packet */
-	skb_release_all(skb);
-
 	kasan_poison_object_data(skbuff_head_cache, skb);
 	nc->skb_cache[nc->skb_count++] = skb;
 
@@ -935,6 +932,14 @@ static void napi_skb_cache_put(struct sk_buff *skb)
 
 void __kfree_skb_defer(struct sk_buff *skb)
 {
+	skb_release_all(skb);
+	napi_skb_cache_put(skb);
+}
+
+void napi_skb_free_stolen_head(struct sk_buff *skb)
+{
+	skb_dst_drop(skb);
+	skb_ext_put(skb);
 	napi_skb_cache_put(skb);
 }
 
@@ -960,6 +965,7 @@ void napi_consume_skb(struct sk_buff *skb, int budget)
 		return;
 	}
 
+	skb_release_all(skb);
 	napi_skb_cache_put(skb);
 }
 EXPORT_SYMBOL(napi_consume_skb);
-- 
2.30.1


