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, 28 insertions, 0 deletions

diff --git a/include/net/can.h b/include/net/can.h
new file mode 100644
index 000000000..6db9e826f
--- /dev/null
+++ b/include/net/can.h
@@ -0,0 +1,28 @@
+/* SPDX-License-Identifier: (GPL-2.0 OR BSD-3-Clause) */
+/*
+ * net/can.h
+ *
+ * Definitions for the CAN network socket buffer extensions
+ *
+ * Copyright (C) 2026 Oliver Hartkopp <socketcan@hartkopp.net>
+ *
+ */
+
+#ifndef _NET_CAN_H
+#define _NET_CAN_H
+
+/**
+ * struct can_skb_ext - skb extensions for CAN specific content
+ * @can_iif: ifindex of the first interface the CAN frame appeared on
+ * @can_framelen: cached echo CAN frame length for bql
+ * @can_gw_hops: can-gw CAN frame time-to-live counter
+ * @can_ext_flags: CAN skb extensions flags
+ */
+struct can_skb_ext {
+	int	can_iif;
+	u16	can_framelen;
+	u8	can_gw_hops;
+	u8	can_ext_flags;
+};
+
+#endif /* _NET_CAN_H */