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Message-ID: <20250627200551.348096-4-edumazet@google.com>
Date: Fri, 27 Jun 2025 20:05:50 +0000
From: Eric Dumazet <edumazet@...gle.com>
To: "David S . Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>,
Paolo Abeni <pabeni@...hat.com>
Cc: Simon Horman <horms@...nel.org>, Willem de Bruijn <willemb@...gle.com>, netdev@...r.kernel.org,
eric.dumazet@...il.com, Eric Dumazet <edumazet@...gle.com>
Subject: [PATCH net-next 3/4] tcp: move tcp_memory_allocated into net_aligned_data
____cacheline_aligned_in_smp attribute only makes sure to align
a field to a cache line. It does not prevent the linker to use
the remaining of the cache line for other variables, causing
potential false sharing.
Move tcp_memory_allocated into a dedicated cache line.
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---
include/net/aligned_data.h | 3 +++
include/net/tcp.h | 1 -
net/core/hotdata.c | 2 ++
net/ipv4/tcp.c | 2 --
net/ipv4/tcp_ipv4.c | 3 ++-
net/ipv6/tcp_ipv6.c | 3 ++-
net/mptcp/protocol.c | 3 ++-
7 files changed, 11 insertions(+), 6 deletions(-)
diff --git a/include/net/aligned_data.h b/include/net/aligned_data.h
index 6538c66efdf90ed51836cf244237ee17019a325d..a60c65a3b370a406b2078f23c3e332f58c84df58 100644
--- a/include/net/aligned_data.h
+++ b/include/net/aligned_data.h
@@ -10,6 +10,9 @@
*/
struct net_aligned_data {
atomic64_t net_cookie ____cacheline_aligned_in_smp;
+#if defined(CONFIG_INET)
+ atomic_long_t tcp_memory_allocated ____cacheline_aligned_in_smp;
+#endif
};
extern struct net_aligned_data net_aligned_data;
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 761c4a0ad386f95f73d72dc013a0952187342b51..bc08de49805cf6fc2ffbec96e42bf12378fd10cf 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -267,7 +267,6 @@ extern long sysctl_tcp_mem[3];
#define TCP_RACK_STATIC_REO_WND 0x2 /* Use static RACK reo wnd */
#define TCP_RACK_NO_DUPTHRESH 0x4 /* Do not use DUPACK threshold in RACK */
-extern atomic_long_t tcp_memory_allocated;
DECLARE_PER_CPU(int, tcp_memory_per_cpu_fw_alloc);
extern struct percpu_counter tcp_sockets_allocated;
diff --git a/net/core/hotdata.c b/net/core/hotdata.c
index e9c03491ab001cc85fd60ad28533649b32d8a003..95d0a4df10069e4529fb9e5b58e8391574085cf1 100644
--- a/net/core/hotdata.c
+++ b/net/core/hotdata.c
@@ -4,6 +4,7 @@
#include <linux/list.h>
#include <net/aligned_data.h>
#include <net/hotdata.h>
+#include <net/ip.h>
#include <net/proto_memory.h>
struct net_hotdata net_hotdata __cacheline_aligned = {
@@ -25,3 +26,4 @@ struct net_hotdata net_hotdata __cacheline_aligned = {
EXPORT_SYMBOL(net_hotdata);
struct net_aligned_data net_aligned_data;
+EXPORT_IPV6_MOD(net_aligned_data);
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 8a3c99246d2ed32ba45849b56830bf128e265763..925b2c572ca23b3f2eba48a38820f6553a2724f4 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -302,8 +302,6 @@ EXPORT_PER_CPU_SYMBOL_GPL(tcp_tw_isn);
long sysctl_tcp_mem[3] __read_mostly;
EXPORT_IPV6_MOD(sysctl_tcp_mem);
-atomic_long_t tcp_memory_allocated ____cacheline_aligned_in_smp; /* Current allocated memory. */
-EXPORT_IPV6_MOD(tcp_memory_allocated);
DEFINE_PER_CPU(int, tcp_memory_per_cpu_fw_alloc);
EXPORT_PER_CPU_SYMBOL_GPL(tcp_memory_per_cpu_fw_alloc);
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 429fb34b075e0bdad0e1c55dd6b1101b3dfe78dd..a9e1d19ffae4159fe1d6da4d2e8ee69e64f8dd55 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -59,6 +59,7 @@
#include <linux/slab.h>
#include <linux/sched.h>
+#include <net/aligned_data.h>
#include <net/net_namespace.h>
#include <net/icmp.h>
#include <net/inet_hashtables.h>
@@ -3391,7 +3392,7 @@ struct proto tcp_prot = {
.sockets_allocated = &tcp_sockets_allocated,
.orphan_count = &tcp_orphan_count,
- .memory_allocated = &tcp_memory_allocated,
+ .memory_allocated = &net_aligned_data.tcp_memory_allocated,
.per_cpu_fw_alloc = &tcp_memory_per_cpu_fw_alloc,
.memory_pressure = &tcp_memory_pressure,
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index f0ce62549d90d6492b8ab139640cca91e4a9c2c7..20d51941e58ae830ab254c4681cc95fd740b88df 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -41,6 +41,7 @@
#include <linux/random.h>
#include <linux/indirect_call_wrapper.h>
+#include <net/aligned_data.h>
#include <net/tcp.h>
#include <net/ndisc.h>
#include <net/inet6_hashtables.h>
@@ -2357,7 +2358,7 @@ struct proto tcpv6_prot = {
.stream_memory_free = tcp_stream_memory_free,
.sockets_allocated = &tcp_sockets_allocated,
- .memory_allocated = &tcp_memory_allocated,
+ .memory_allocated = &net_aligned_data.tcp_memory_allocated,
.per_cpu_fw_alloc = &tcp_memory_per_cpu_fw_alloc,
.memory_pressure = &tcp_memory_pressure,
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index e7972e633236e0451f0321ff4b0a8d1b37282d5f..5f904fc5ac4c63e8b6c7c9aa79f17e8dcdf1a007 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -11,6 +11,7 @@
#include <linux/netdevice.h>
#include <linux/sched/signal.h>
#include <linux/atomic.h>
+#include <net/aligned_data.h>
#include <net/sock.h>
#include <net/inet_common.h>
#include <net/inet_hashtables.h>
@@ -3729,7 +3730,7 @@ static struct proto mptcp_prot = {
.stream_memory_free = mptcp_stream_memory_free,
.sockets_allocated = &mptcp_sockets_allocated,
- .memory_allocated = &tcp_memory_allocated,
+ .memory_allocated = &net_aligned_data.tcp_memory_allocated,
.per_cpu_fw_alloc = &tcp_memory_per_cpu_fw_alloc,
.memory_pressure = &tcp_memory_pressure,
--
2.50.0.727.gbf7dc18ff4-goog
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