ftrace: Synchronize the initialization of ftrace_opsgrafted

There's some internal state that ftrace_ops needs to have set, but since
it can be declared outside of the ftrace.c code, it calls
ftrace_ops_init() on the ops in every global function. The issue is that
if two tasks call it on the same ops at the same time it is possible to
have the initialization of one corrupt the initialization of the other
call.

Create a ops_mutex to use to synchronize every initialization of the
ftrace_ops. The mutex is taken within checking the ftrace_ops flag that
states it was initializied but the flag is checked again after the mutex
has been taken. Checking first outside the mutex allows it to shortcut
having to take the mutex. But then the check needs to be done again after
the mute is taken in case of races.

Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home
Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock")
Reported-by: sashiko-bot@kernel.org
Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 124 insertions, 0 deletions

diff --git a/net/rxrpc/net_ns.c b/net/rxrpc/net_ns.c
new file mode 100644
index 000000000..9a9834145
--- /dev/null
+++ b/net/rxrpc/net_ns.c
@@ -0,0 +1,124 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* rxrpc network namespace handling.
+ *
+ * Copyright (C) 2017 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ */
+
+#include <linux/proc_fs.h>
+#include "ar-internal.h"
+
+unsigned int rxrpc_net_id;
+
+static void rxrpc_service_conn_reap_timeout(struct timer_list *timer)
+{
+	struct rxrpc_net *rxnet =
+		container_of(timer, struct rxrpc_net, service_conn_reap_timer);
+
+	if (rxnet->live)
+		rxrpc_queue_work(&rxnet->service_conn_reaper);
+}
+
+static void rxrpc_peer_keepalive_timeout(struct timer_list *timer)
+{
+	struct rxrpc_net *rxnet =
+		container_of(timer, struct rxrpc_net, peer_keepalive_timer);
+
+	if (rxnet->live)
+		rxrpc_queue_work(&rxnet->peer_keepalive_work);
+}
+
+/*
+ * Initialise a per-network namespace record.
+ */
+static __net_init int rxrpc_init_net(struct net *net)
+{
+	struct rxrpc_net *rxnet = rxrpc_net(net);
+	int ret, i;
+
+	rxnet->live = true;
+	get_random_bytes(&rxnet->epoch, sizeof(rxnet->epoch));
+	rxnet->epoch |= RXRPC_RANDOM_EPOCH;
+
+	INIT_LIST_HEAD(&rxnet->calls);
+	spin_lock_init(&rxnet->call_lock);
+	atomic_set(&rxnet->nr_calls, 1);
+
+	atomic_set(&rxnet->nr_conns, 1);
+	INIT_LIST_HEAD(&rxnet->bundle_proc_list);
+	INIT_LIST_HEAD(&rxnet->conn_proc_list);
+	INIT_LIST_HEAD(&rxnet->service_conns);
+	rwlock_init(&rxnet->conn_lock);
+	INIT_WORK(&rxnet->service_conn_reaper,
+		  rxrpc_service_connection_reaper);
+	timer_setup(&rxnet->service_conn_reap_timer,
+		    rxrpc_service_conn_reap_timeout, 0);
+
+	atomic_set(&rxnet->nr_client_conns, 0);
+
+	INIT_HLIST_HEAD(&rxnet->local_endpoints);
+	mutex_init(&rxnet->local_mutex);
+
+	hash_init(rxnet->peer_hash);
+	spin_lock_init(&rxnet->peer_hash_lock);
+	for (i = 0; i < ARRAY_SIZE(rxnet->peer_keepalive); i++)
+		INIT_LIST_HEAD(&rxnet->peer_keepalive[i]);
+	INIT_LIST_HEAD(&rxnet->peer_keepalive_new);
+	timer_setup(&rxnet->peer_keepalive_timer,
+		    rxrpc_peer_keepalive_timeout, 0);
+	INIT_WORK(&rxnet->peer_keepalive_work, rxrpc_peer_keepalive_worker);
+	rxnet->peer_keepalive_base = ktime_get_seconds();
+
+	ret = -ENOMEM;
+	rxnet->proc_net = proc_net_mkdir(net, "rxrpc", net->proc_net);
+	if (!rxnet->proc_net)
+		goto err_proc;
+
+	proc_create_net("calls", 0444, rxnet->proc_net, &rxrpc_call_seq_ops,
+			sizeof(struct seq_net_private));
+	proc_create_net("conns", 0444, rxnet->proc_net,
+			&rxrpc_connection_seq_ops,
+			sizeof(struct seq_net_private));
+	proc_create_net("bundles", 0444, rxnet->proc_net,
+			&rxrpc_bundle_seq_ops,
+			sizeof(struct seq_net_private));
+	proc_create_net("peers", 0444, rxnet->proc_net,
+			&rxrpc_peer_seq_ops,
+			sizeof(struct seq_net_private));
+	proc_create_net("locals", 0444, rxnet->proc_net,
+			&rxrpc_local_seq_ops,
+			sizeof(struct seq_net_private));
+	proc_create_net_single_write("stats", S_IFREG | 0644, rxnet->proc_net,
+				     rxrpc_stats_show, rxrpc_stats_clear, NULL);
+	return 0;
+
+err_proc:
+	rxnet->live = false;
+	return ret;
+}
+
+/*
+ * Clean up a per-network namespace record.
+ */
+static __net_exit void rxrpc_exit_net(struct net *net)
+{
+	struct rxrpc_net *rxnet = rxrpc_net(net);
+
+	rxnet->live = false;
+	timer_delete_sync(&rxnet->peer_keepalive_timer);
+	cancel_work_sync(&rxnet->peer_keepalive_work);
+	/* Remove the timer again as the worker may have restarted it. */
+	timer_delete_sync(&rxnet->peer_keepalive_timer);
+	rxrpc_destroy_all_calls(rxnet);
+	rxrpc_destroy_all_connections(rxnet);
+	rxrpc_destroy_all_peers(rxnet);
+	rxrpc_destroy_all_locals(rxnet);
+	proc_remove(rxnet->proc_net);
+}
+
+struct pernet_operations rxrpc_net_ops = {
+	.init	= rxrpc_init_net,
+	.exit	= rxrpc_exit_net,
+	.id	= &rxrpc_net_id,
+	.size	= sizeof(struct rxrpc_net),
+};