Merge branch 'remove-sk-skb-caches'

Paolo Abeni says:

====================
net: remove sk skb caches

Eric noted we would be better off reverting the sk
skb caches.

MPTCP relies on such a feature, so we need a
little refactor of the MPTCP tx path before the mentioned
revert.

The first patch exposes additional TCP helpers. The 2nd patch
changes the MPTCP code to do locally the whole skb allocation
and updating, so it does not rely anymore on core TCP helpers
for that nor the sk skb cache.

As a side effect, we can make the tcp_build_frag helper static.

Finally, we can pull Eric's revert.

RFC -> v1:
 - drop driver specific patch - no more needed after helper rename
 - rename skb_entail -> tcp_skb_entail (Eric)
 - preserve the tcp_build_frag helpwe, just make it static (Eric)
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 6 insertions, 32 deletions

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index e8b48df73c85..414c179c28e0 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -325,11 +325,6 @@ struct tcp_splice_state {
 unsigned long tcp_memory_pressure __read_mostly;
 EXPORT_SYMBOL_GPL(tcp_memory_pressure);
 
-DEFINE_STATIC_KEY_FALSE(tcp_rx_skb_cache_key);
-EXPORT_SYMBOL(tcp_rx_skb_cache_key);
-
-DEFINE_STATIC_KEY_FALSE(tcp_tx_skb_cache_key);
-
 void tcp_enter_memory_pressure(struct sock *sk)
 {
 	unsigned long val;
@@ -647,7 +642,7 @@ int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg)
 }
 EXPORT_SYMBOL(tcp_ioctl);
 
-static inline void tcp_mark_push(struct tcp_sock *tp, struct sk_buff *skb)
+void tcp_mark_push(struct tcp_sock *tp, struct sk_buff *skb)
 {
 	TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_PSH;
 	tp->pushed_seq = tp->write_seq;
@@ -658,7 +653,7 @@ static inline bool forced_push(const struct tcp_sock *tp)
 	return after(tp->write_seq, tp->pushed_seq + (tp->max_window >> 1));
 }
 
-static void skb_entail(struct sock *sk, struct sk_buff *skb)
+void tcp_skb_entail(struct sock *sk, struct sk_buff *skb)
 {
 	struct tcp_sock *tp = tcp_sk(sk);
 	struct tcp_skb_cb *tcb = TCP_SKB_CB(skb);
@@ -866,18 +861,6 @@ struct sk_buff *sk_stream_alloc_skb(struct sock *sk, int size, gfp_t gfp,
 {
 	struct sk_buff *skb;
 
-	if (likely(!size)) {
-		skb = sk->sk_tx_skb_cache;
-		if (skb) {
-			skb->truesize = SKB_TRUESIZE(skb_end_offset(skb));
-			sk->sk_tx_skb_cache = NULL;
-			pskb_trim(skb, 0);
-			INIT_LIST_HEAD(&skb->tcp_tsorted_anchor);
-			skb_shinfo(skb)->tx_flags = 0;
-			memset(TCP_SKB_CB(skb), 0, sizeof(struct tcp_skb_cb));
-			return skb;
-		}
-	}
 	/* The TCP header must be at least 32-bit aligned.  */
 	size = ALIGN(size, 4);
 
@@ -963,8 +946,8 @@ void tcp_remove_empty_skb(struct sock *sk, struct sk_buff *skb)
 	}
 }
 
-struct sk_buff *tcp_build_frag(struct sock *sk, int size_goal, int flags,
-			       struct page *page, int offset, size_t *size)
+static struct sk_buff *tcp_build_frag(struct sock *sk, int size_goal, int flags,
+				      struct page *page, int offset, size_t *size)
 {
 	struct sk_buff *skb = tcp_write_queue_tail(sk);
 	struct tcp_sock *tp = tcp_sk(sk);
@@ -985,7 +968,7 @@ new_segment:
 #ifdef CONFIG_TLS_DEVICE
 		skb->decrypted = !!(flags & MSG_SENDPAGE_DECRYPTED);
 #endif
-		skb_entail(sk, skb);
+		tcp_skb_entail(sk, skb);
 		copy = size_goal;
 	}
 
@@ -1314,7 +1297,7 @@ new_segment:
 			process_backlog++;
 			skb->ip_summed = CHECKSUM_PARTIAL;
 
-			skb_entail(sk, skb);
+			tcp_skb_entail(sk, skb);
 			copy = size_goal;
 
 			/* All packets are restored as if they have
@@ -2920,11 +2903,6 @@ void tcp_write_queue_purge(struct sock *sk)
 		sk_wmem_free_skb(sk, skb);
 	}
 	tcp_rtx_queue_purge(sk);
-	skb = sk->sk_tx_skb_cache;
-	if (skb) {
-		__kfree_skb(skb);
-		sk->sk_tx_skb_cache = NULL;
-	}
 	INIT_LIST_HEAD(&tcp_sk(sk)->tsorted_sent_queue);
 	sk_mem_reclaim(sk);
 	tcp_clear_all_retrans_hints(tcp_sk(sk));
@@ -2961,10 +2939,6 @@ int tcp_disconnect(struct sock *sk, int flags)
 
 	tcp_clear_xmit_timers(sk);
 	__skb_queue_purge(&sk->sk_receive_queue);
-	if (sk->sk_rx_skb_cache) {
-		__kfree_skb(sk->sk_rx_skb_cache);
-		sk->sk_rx_skb_cache = NULL;
-	}
 	WRITE_ONCE(tp->copied_seq, tp->rcv_nxt);
 	tp->urg_data = 0;
 	tcp_write_queue_purge(sk);