Commit 82d9e6b9 authored by Sebastian Andrzej Siewior's avatar Sebastian Andrzej Siewior Committed by Paolo Abeni
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mptcp: Use nested-BH locking for hmac_storage 



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: default avatarSebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: https://patch.msgid.link/20250512092736.229935-13-bigeasy@linutronix.de


Signed-off-by: default avatarPaolo Abeni <pabeni@redhat.com>
parent 20d677d3

net/mptcp/protocol.c

+3 −1
Original line number Diff line number Diff line
@@ -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 */

net/mptcp/protocol.h

+8 −1
Original line number Diff line number Diff line
@@ -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;

}