netdev - [PATCH net-next 4/4] udp: move udp_memory_allocated into net_aligned

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Message-ID: <20250627200551.348096-5-edumazet@google.com>
Date: Fri, 27 Jun 2025 20:05:51 +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 4/4] udp: move udp_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.

Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---
 include/net/aligned_data.h | 1 +
 include/net/udp.h          | 1 -
 net/ipv4/udp.c             | 4 +---
 net/ipv4/udp_impl.h        | 1 +
 net/ipv4/udplite.c         | 2 +-
 net/ipv6/udp.c             | 2 +-
 net/ipv6/udp_impl.h        | 1 +
 net/ipv6/udplite.c         | 2 +-
 8 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/include/net/aligned_data.h b/include/net/aligned_data.h
index a60c65a3b370a406b2078f23c3e332f58c84df58..fc07461e31352eb757c34867ea9b458fb9e539f4 100644
--- a/include/net/aligned_data.h
+++ b/include/net/aligned_data.h
@@ -12,6 +12,7 @@ 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;
+	atomic_long_t udp_memory_allocated ____cacheline_aligned_in_smp;
 #endif
 };
 
diff --git a/include/net/udp.h b/include/net/udp.h
index a772510b2aa58a922dc4dd5bd7cb7f7f0c1ce0e3..f8ae2c4ade141d27e4af3376f5a177e46d5b39ea 100644
--- a/include/net/udp.h
+++ b/include/net/udp.h
@@ -205,7 +205,6 @@ static inline void udp_hash4_dec(struct udp_hslot *hslot2)
 
 extern struct proto udp_prot;
 
-extern atomic_long_t udp_memory_allocated;
 DECLARE_PER_CPU(int, udp_memory_per_cpu_fw_alloc);
 
 /* sysctl variables for udp */
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 19573ee64a0f18cf55df34ace1956e9c3e20172c..49f43c54cfb0e3ac85c1a6202f3d6a2f1ca6d0ba 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -127,8 +127,6 @@ struct udp_table udp_table __read_mostly;
 long sysctl_udp_mem[3] __read_mostly;
 EXPORT_IPV6_MOD(sysctl_udp_mem);
 
-atomic_long_t udp_memory_allocated ____cacheline_aligned_in_smp;
-EXPORT_IPV6_MOD(udp_memory_allocated);
 DEFINE_PER_CPU(int, udp_memory_per_cpu_fw_alloc);
 EXPORT_PER_CPU_SYMBOL_GPL(udp_memory_per_cpu_fw_alloc);
 
@@ -3235,7 +3233,7 @@ struct proto udp_prot = {
 #ifdef CONFIG_BPF_SYSCALL
 	.psock_update_sk_prot	= udp_bpf_update_proto,
 #endif
-	.memory_allocated	= &udp_memory_allocated,
+	.memory_allocated	= &net_aligned_data.udp_memory_allocated,
 	.per_cpu_fw_alloc	= &udp_memory_per_cpu_fw_alloc,
 
 	.sysctl_mem		= sysctl_udp_mem,
diff --git a/net/ipv4/udp_impl.h b/net/ipv4/udp_impl.h
index e1ff3a37599614b18a0b621534019a7bd71ea901..c7142213fc2112c9e423caa5e6d84bafeaca9936 100644
--- a/net/ipv4/udp_impl.h
+++ b/net/ipv4/udp_impl.h
@@ -1,6 +1,7 @@
 /* SPDX-License-Identifier: GPL-2.0 */
 #ifndef _UDP4_IMPL_H
 #define _UDP4_IMPL_H
+#include <net/aligned_data.h>
 #include <net/udp.h>
 #include <net/udplite.h>
 #include <net/protocol.h>
diff --git a/net/ipv4/udplite.c b/net/ipv4/udplite.c
index af37af3ab727bffeebe5c41d84cb7c130f49c50d..d3e621a11a1aa4cafb62eb53ddc0ed1ca517a7fe 100644
--- a/net/ipv4/udplite.c
+++ b/net/ipv4/udplite.c
@@ -60,7 +60,7 @@ struct proto 	udplite_prot = {
 	.rehash		   = udp_v4_rehash,
 	.get_port	   = udp_v4_get_port,
 
-	.memory_allocated  = &udp_memory_allocated,
+	.memory_allocated  = &net_aligned_data.udp_memory_allocated,
 	.per_cpu_fw_alloc  = &udp_memory_per_cpu_fw_alloc,
 
 	.sysctl_mem	   = sysctl_udp_mem,
diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index ebb95d8bc6819f72842fd1567e73fcef4f1e0ed0..6bbdadbd5fecccfb7de99f05c6fb179393e162f2 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -1925,7 +1925,7 @@ struct proto udpv6_prot = {
 	.psock_update_sk_prot	= udp_bpf_update_proto,
 #endif
 
-	.memory_allocated	= &udp_memory_allocated,
+	.memory_allocated	= &net_aligned_data.udp_memory_allocated,
 	.per_cpu_fw_alloc	= &udp_memory_per_cpu_fw_alloc,
 
 	.sysctl_mem		= sysctl_udp_mem,
diff --git a/net/ipv6/udp_impl.h b/net/ipv6/udp_impl.h
index 0590f566379d7d07dfdd1b0ae808b9d8964eb5aa..8a406be25a3a6dee687a6a02ea0b6a28428abb86 100644
--- a/net/ipv6/udp_impl.h
+++ b/net/ipv6/udp_impl.h
@@ -1,6 +1,7 @@
 /* SPDX-License-Identifier: GPL-2.0 */
 #ifndef _UDP6_IMPL_H
 #define _UDP6_IMPL_H
+#include <net/aligned_data.h>
 #include <net/udp.h>
 #include <net/udplite.h>
 #include <net/protocol.h>
diff --git a/net/ipv6/udplite.c b/net/ipv6/udplite.c
index a60bec9b14f14a5b2d271f9965b5fca3d2a440c8..2cec542437f74eba9540fc464ee70d8b0bc0be79 100644
--- a/net/ipv6/udplite.c
+++ b/net/ipv6/udplite.c
@@ -59,7 +59,7 @@ struct proto udplitev6_prot = {
 	.rehash		   = udp_v6_rehash,
 	.get_port	   = udp_v6_get_port,
 
-	.memory_allocated  = &udp_memory_allocated,
+	.memory_allocated  = &net_aligned_data.udp_memory_allocated,
 	.per_cpu_fw_alloc  = &udp_memory_per_cpu_fw_alloc,
 
 	.sysctl_mem	   = sysctl_udp_mem,
-- 
2.50.0.727.gbf7dc18ff4-goog