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, 34 insertions, 0 deletions

diff --git a/sound/firewire/fcp.h b/sound/firewire/fcp.h
new file mode 100644
index 000000000..512f7c409
--- /dev/null
+++ b/sound/firewire/fcp.h
@@ -0,0 +1,34 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef SOUND_FIREWIRE_FCP_H_INCLUDED
+#define SOUND_FIREWIRE_FCP_H_INCLUDED
+
+#define	AVC_PLUG_INFO_BUF_BYTES	4
+
+struct fw_unit;
+
+/*
+ * AV/C Digital Interface Command Set General Specification 4.2
+ * (Sep 2004, 1394TA)
+ */
+enum avc_general_plug_dir {
+	AVC_GENERAL_PLUG_DIR_IN		= 0,
+	AVC_GENERAL_PLUG_DIR_OUT	= 1,
+	AVC_GENERAL_PLUG_DIR_COUNT
+};
+int avc_general_set_sig_fmt(struct fw_unit *unit, unsigned int rate,
+			    enum avc_general_plug_dir dir,
+			    unsigned short plug);
+int avc_general_get_sig_fmt(struct fw_unit *unit, unsigned int *rate,
+			    enum avc_general_plug_dir dir,
+			    unsigned short plug);
+int avc_general_get_plug_info(struct fw_unit *unit, unsigned int subunit_type,
+			      unsigned int subunit_id, unsigned int subfunction,
+			      u8 info[AVC_PLUG_INFO_BUF_BYTES]);
+
+int fcp_avc_transaction(struct fw_unit *unit,
+			const void *command, unsigned int command_size,
+			void *response, unsigned int response_size,
+			unsigned int response_match_bytes);
+void fcp_bus_reset(struct fw_unit *unit);
+
+#endif