[PATCH net-next v4 12/15] mptcp: Use nested-BH locking for hmac_storage
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: 2025-05-12 09:27:48
Also in:
linux-rt-devel, mptcp
Subsystem:
networking [general], networking [mptcp], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Matthieu Baerts, Mat Martineau, Linus Torvalds
mptcp_delegated_actions is a per-CPU variable and relies on disabled BH for its locking. Without per-CPU locking in local_bh_disable() on PREEMPT_RT this data structure requires explicit locking. Add a local_lock_t to the data structure and use local_lock_nested_bh() for locking. This change adds only lockdep coverage and does not alter the functional behaviour for !PREEMPT_RT. Cc: Matthieu Baerts <matttbe@kernel.org> Cc: Mat Martineau <martineau@kernel.org> Cc: Geliang Tang <geliang@kernel.org> Cc: mptcp@lists.linux.dev Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> --- net/mptcp/protocol.c | 4 +++- net/mptcp/protocol.h | 9 ++++++++- 2 files changed, 11 insertions(+), 2 deletions(-)
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 44f7ab463d755..b6cb93a3f9a2d 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c@@ -46,7 +46,9 @@ static struct percpu_counter mptcp_sockets_allocated ____cacheline_aligned_in_sm static void __mptcp_destroy_sock(struct sock *sk); static void mptcp_check_send_data_fin(struct sock *sk); -DEFINE_PER_CPU(struct mptcp_delegated_action, mptcp_delegated_actions); +DEFINE_PER_CPU(struct mptcp_delegated_action, mptcp_delegated_actions) = { + .bh_lock = INIT_LOCAL_LOCK(bh_lock), +}; static struct net_device *mptcp_napi_dev; /* Returns end sequence number of the receiver's advertised window */
diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index d409586b5977f..88cc2a857adce 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h@@ -479,6 +479,7 @@ mptcp_subflow_rsk(const struct request_sock *rsk) struct mptcp_delegated_action { struct napi_struct napi; + local_lock_t bh_lock; struct list_head head; };
@@ -670,9 +671,11 @@ static inline void mptcp_subflow_delegate(struct mptcp_subflow_context *subflow, if (WARN_ON_ONCE(!list_empty(&subflow->delegated_node))) return; + local_lock_nested_bh(&mptcp_delegated_actions.bh_lock); delegated = this_cpu_ptr(&mptcp_delegated_actions); schedule = list_empty(&delegated->head); list_add_tail(&subflow->delegated_node, &delegated->head); + local_unlock_nested_bh(&mptcp_delegated_actions.bh_lock); sock_hold(mptcp_subflow_tcp_sock(subflow)); if (schedule) napi_schedule(&delegated->napi);
@@ -684,11 +687,15 @@ mptcp_subflow_delegated_next(struct mptcp_delegated_action *delegated) { struct mptcp_subflow_context *ret; - if (list_empty(&delegated->head)) + local_lock_nested_bh(&mptcp_delegated_actions.bh_lock); + if (list_empty(&delegated->head)) { + local_unlock_nested_bh(&mptcp_delegated_actions.bh_lock); return NULL; + } ret = list_first_entry(&delegated->head, struct mptcp_subflow_context, delegated_node); list_del_init(&ret->delegated_node); + local_unlock_nested_bh(&mptcp_delegated_actions.bh_lock); return ret; }
--
2.49.0