tcp: remove sk_{tr}x_skb_cache

This reverts the following patches :

- commit 2e05fcae83c4 ("tcp: fix compile error if !CONFIG_SYSCTL")
- commit 4f661542a402 ("tcp: fix zerocopy and notsent_lowat issues")
- commit 472c2e07eef0 ("tcp: add one skb cache for tx")
- commit 8b27dae5a2e8 ("tcp: add one skb cache for rx")

Having a cache of one skb (in each direction) per TCP socket is fragile,
since it can cause a significant increase of memory needs,
and not good enough for high speed flows anyway where more than one skb
is needed.

We want instead to add a generic infrastructure, with more flexible
per-cpu caches, for alien NUMA nodes.

Acked-by: Paolo Abeni <pabeni@redhat.com>
Acked-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 0 insertions, 26 deletions

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 29cb7bf9dc1c..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;
@@ -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);
 
@@ -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);