[PATCH net-next v3] soreuseport: publish num_socks with acquire/release
From: Jinjie Ruan <hidden>
Date: 2026-09-02 07:18:14
Also in:
lkml
Subsystem:
networking [general], networking [sockets], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Kuniyuki Iwashima, Willem de Bruijn, Linus Torvalds
Replace the smp_wmb()/smp_rmb() barrier pair with smp_store_release()/smp_load_acquire() on reuse->num_socks. Writers publish socks[] updates via release before incrementing or decrementing the count; readers acquire the count before accessing socks[], ensuring they observe a consistent view. The detach path gains proper ordering between the socks[] write and the decrement, which was previously unordered. No functional change intended. Cc: Eric Dumazet <edumazet@google.com> Cc: Kuniyuki Iwashima <kuniyu@google.com> Cc: Paolo Abeni <pabeni@redhat.com> Cc: Willem de Bruijn <willemb@google.com> Cc: "David S. Miller" <davem@davemloft.net> Cc: Jakub Kicinski <kuba@kernel.org> Cc: Simon Horman <horms@kernel.org> Assisted-by: DeepSeek:DeepSeek-V3 Signed-off-by: Jinjie Ruan <redacted> --- v3: - Split out from following patch set as Kuniyuki suggested. Link: https://lore.kernel.org/all/20260901024234.135119-1-ruanjinjie@huawei.com/ (local) --- net/core/sock_reuseport.c | 20 ++++++++------------ 1 file changed, 8 insertions(+), 12 deletions(-)
diff --git a/net/core/sock_reuseport.c b/net/core/sock_reuseport.c
index 29948cb44b7d..6d3c511d1def 100644
--- a/net/core/sock_reuseport.c
+++ b/net/core/sock_reuseport.c@@ -125,9 +125,8 @@ static void __reuseport_add_sock(struct sock *sk, struct sock_reuseport *reuse) { reuse->socks[reuse->num_socks] = sk; - /* paired with smp_rmb() in reuseport_(select|migrate)_sock() */ - smp_wmb(); - reuse->num_socks++; + /* paired with smp_load_acquire() in reuseport_(select|migrate)_sock() */ + smp_store_release(&reuse->num_socks, reuse->num_socks + 1); reuseport_get_incoming_cpu(sk, reuse); }
@@ -140,7 +139,8 @@ static bool __reuseport_detach_sock(struct sock *sk, return false; reuse->socks[i] = reuse->socks[reuse->num_socks - 1]; - reuse->num_socks--; + /* paired with smp_load_acquire() in reuseport_(select|migrate)_sock() */ + smp_store_release(&reuse->num_socks, reuse->num_socks - 1); reuseport_put_incoming_cpu(sk, reuse); return true;
@@ -583,11 +583,9 @@ struct sock *reuseport_select_sock(struct sock *sk, goto out; prog = rcu_dereference(reuse->prog); - socks = READ_ONCE(reuse->num_socks); + /* paired with smp_store_release() in __reuseport_add_sock() */ + socks = smp_load_acquire(&reuse->num_socks); if (likely(socks)) { - /* paired with smp_wmb() in __reuseport_add_sock() */ - smp_rmb(); - if (!prog || !skb) goto select_by_hash;
@@ -634,13 +632,11 @@ struct sock *reuseport_migrate_sock(struct sock *sk, if (!reuse) goto out; - socks = READ_ONCE(reuse->num_socks); + /* paired with smp_store_release() in __reuseport_add_sock() */ + socks = smp_load_acquire(&reuse->num_socks); if (unlikely(!socks)) goto failure; - /* paired with smp_wmb() in __reuseport_add_sock() */ - smp_rmb(); - hash = migrating_sk->sk_hash; prog = rcu_dereference(reuse->prog); if (!prog || prog->expected_attach_type != BPF_SK_REUSEPORT_SELECT_OR_MIGRATE) {
--
2.34.1