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, 46 insertions, 0 deletions

diff --git a/net/sunrpc/sunrpc.h b/net/sunrpc/sunrpc.h
new file mode 100644
index 000000000..e3c6e3b63
--- /dev/null
+++ b/net/sunrpc/sunrpc.h
@@ -0,0 +1,46 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/******************************************************************************
+
+(c) 2008 NetApp.  All Rights Reserved.
+
+
+******************************************************************************/
+
+/*
+ * Functions and macros used internally by RPC
+ */
+
+#ifndef _NET_SUNRPC_SUNRPC_H
+#define _NET_SUNRPC_SUNRPC_H
+
+#include <linux/net.h>
+
+/*
+ * Header for dynamically allocated rpc buffers.
+ */
+struct rpc_buffer {
+	size_t	len;
+	char	data[];
+};
+
+static inline int sock_is_loopback(struct sock *sk)
+{
+	struct dst_entry *dst;
+	int loopback = 0;
+	rcu_read_lock();
+	dst = rcu_dereference(sk->sk_dst_cache);
+	if (dst && dst->dev &&
+	    (dst->dev->features & NETIF_F_LOOPBACK))
+		loopback = 1;
+	rcu_read_unlock();
+	return loopback;
+}
+
+struct svc_serv;
+struct svc_rqst;
+int rpc_clients_notifier_register(void);
+void rpc_clients_notifier_unregister(void);
+void auth_domain_cleanup(void);
+void svc_sock_update_bufs(struct svc_serv *serv);
+enum svc_auth_status svc_authenticate(struct svc_rqst *rqstp);
+#endif /* _NET_SUNRPC_SUNRPC_H */