Commit d8b81175 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller

tcp: remove sk_{tr}x_skb_cache

This reverts the following patches :

- commit 2e05fcae ("tcp: fix compile error if !CONFIG_SYSCTL")
- commit 4f661542 ("tcp: fix zerocopy and notsent_lowat issues")
- commit 472c2e07 ("tcp: add one skb cache for tx")
- commit 8b27dae5 ("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: default avatarPaolo Abeni <pabeni@redhat.com>
Acked-by: default avatarMat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent ff6fb083
......@@ -989,14 +989,6 @@ tcp_challenge_ack_limit - INTEGER
in RFC 5961 (Improving TCP's Robustness to Blind In-Window Attacks)
Default: 1000
tcp_rx_skb_cache - BOOLEAN
Controls a per TCP socket cache of one skb, that might help
performance of some workloads. This might be dangerous
on systems with a lot of TCP sockets, since it increases
memory usage.
Default: 0 (disabled)
UDP variables
=============
......
......@@ -262,7 +262,6 @@ struct bpf_local_storage;
* @sk_dst_cache: destination cache
* @sk_dst_pending_confirm: need to confirm neighbour
* @sk_policy: flow policy
* @sk_rx_skb_cache: cache copy of recently accessed RX skb
* @sk_receive_queue: incoming packets
* @sk_wmem_alloc: transmit queue bytes committed
* @sk_tsq_flags: TCP Small Queues flags
......@@ -328,7 +327,6 @@ struct bpf_local_storage;
* @sk_peek_off: current peek_offset value
* @sk_send_head: front of stuff to transmit
* @tcp_rtx_queue: TCP re-transmit queue [union with @sk_send_head]
* @sk_tx_skb_cache: cache copy of recently accessed TX skb
* @sk_security: used by security modules
* @sk_mark: generic packet mark
* @sk_cgrp_data: cgroup data for this cgroup
......@@ -393,7 +391,6 @@ struct sock {
atomic_t sk_drops;
int sk_rcvlowat;
struct sk_buff_head sk_error_queue;
struct sk_buff *sk_rx_skb_cache;
struct sk_buff_head sk_receive_queue;
/*
* The backlog queue is special, it is always used with
......@@ -442,7 +439,6 @@ struct sock {
struct sk_buff *sk_send_head;
struct rb_root tcp_rtx_queue;
};
struct sk_buff *sk_tx_skb_cache;
struct sk_buff_head sk_write_queue;
__s32 sk_peek_off;
int sk_write_pending;
......@@ -1555,18 +1551,10 @@ static inline void sk_mem_uncharge(struct sock *sk, int size)
__sk_mem_reclaim(sk, 1 << 20);
}
DECLARE_STATIC_KEY_FALSE(tcp_tx_skb_cache_key);
static inline void sk_wmem_free_skb(struct sock *sk, struct sk_buff *skb)
{
sk_wmem_queued_add(sk, -skb->truesize);
sk_mem_uncharge(sk, skb->truesize);
if (static_branch_unlikely(&tcp_tx_skb_cache_key) &&
!sk->sk_tx_skb_cache && !skb_cloned(skb)) {
skb_ext_reset(skb);
skb_zcopy_clear(skb, true);
sk->sk_tx_skb_cache = skb;
return;
}
__kfree_skb(skb);
}
......@@ -2575,7 +2563,6 @@ static inline void skb_setup_tx_timestamp(struct sk_buff *skb, __u16 tsflags)
&skb_shinfo(skb)->tskey);
}
DECLARE_STATIC_KEY_FALSE(tcp_rx_skb_cache_key);
/**
* sk_eat_skb - Release a skb if it is no longer needed
* @sk: socket to eat this skb from
......@@ -2587,12 +2574,6 @@ DECLARE_STATIC_KEY_FALSE(tcp_rx_skb_cache_key);
static inline void sk_eat_skb(struct sock *sk, struct sk_buff *skb)
{
__skb_unlink(skb, &sk->sk_receive_queue);
if (static_branch_unlikely(&tcp_rx_skb_cache_key) &&
!sk->sk_rx_skb_cache) {
sk->sk_rx_skb_cache = skb;
skb_orphan(skb);
return;
}
__kfree_skb(skb);
}
......
......@@ -133,10 +133,6 @@ void inet_sock_destruct(struct sock *sk)
struct inet_sock *inet = inet_sk(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;
}
__skb_queue_purge(&sk->sk_error_queue);
sk_mem_reclaim(sk);
......
......@@ -585,18 +585,6 @@ static struct ctl_table ipv4_table[] = {
.extra1 = &sysctl_fib_sync_mem_min,
.extra2 = &sysctl_fib_sync_mem_max,
},
{
.procname = "tcp_rx_skb_cache",
.data = &tcp_rx_skb_cache_key.key,
.mode = 0644,
.proc_handler = proc_do_static_key,
},
{
.procname = "tcp_tx_skb_cache",
.data = &tcp_tx_skb_cache_key.key,
.mode = 0644,
.proc_handler = proc_do_static_key,
},
{ }
};
......
......@@ -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);
......
......@@ -1941,7 +1941,6 @@ static void tcp_v4_fill_cb(struct sk_buff *skb, const struct iphdr *iph,
int tcp_v4_rcv(struct sk_buff *skb)
{
struct net *net = dev_net(skb->dev);
struct sk_buff *skb_to_free;
int sdif = inet_sdif(skb);
int dif = inet_iif(skb);
const struct iphdr *iph;
......@@ -2082,17 +2081,12 @@ int tcp_v4_rcv(struct sk_buff *skb)
tcp_segs_in(tcp_sk(sk), skb);
ret = 0;
if (!sock_owned_by_user(sk)) {
skb_to_free = sk->sk_rx_skb_cache;
sk->sk_rx_skb_cache = NULL;
ret = tcp_v4_do_rcv(sk, skb);
} else {
if (tcp_add_backlog(sk, skb))
goto discard_and_relse;
skb_to_free = NULL;
}
bh_unlock_sock(sk);
if (skb_to_free)
__kfree_skb(skb_to_free);
put_and_return:
if (refcounted)
......
......@@ -1618,7 +1618,6 @@ static void tcp_v6_fill_cb(struct sk_buff *skb, const struct ipv6hdr *hdr,
INDIRECT_CALLABLE_SCOPE int tcp_v6_rcv(struct sk_buff *skb)
{
struct sk_buff *skb_to_free;
int sdif = inet6_sdif(skb);
int dif = inet6_iif(skb);
const struct tcphdr *th;
......@@ -1754,17 +1753,12 @@ INDIRECT_CALLABLE_SCOPE int tcp_v6_rcv(struct sk_buff *skb)
tcp_segs_in(tcp_sk(sk), skb);
ret = 0;
if (!sock_owned_by_user(sk)) {
skb_to_free = sk->sk_rx_skb_cache;
sk->sk_rx_skb_cache = NULL;
ret = tcp_v6_do_rcv(sk, skb);
} else {
if (tcp_add_backlog(sk, skb))
goto discard_and_relse;
skb_to_free = NULL;
}
bh_unlock_sock(sk);
if (skb_to_free)
__kfree_skb(skb_to_free);
put_and_return:
if (refcounted)
sock_put(sk);
......
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