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, 53 insertions, 0 deletions

diff --git a/sound/usb/6fire/control.h b/sound/usb/6fire/control.h
new file mode 100644
index 000000000..ae57704d9
--- /dev/null
+++ b/sound/usb/6fire/control.h
@@ -0,0 +1,53 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Linux driver for TerraTec DMX 6Fire USB
+ *
+ * Author:	Torsten Schenk <torsten.schenk@zoho.com>
+ * Created:	Jan 01, 2011
+ * Copyright:	(C) Torsten Schenk
+ */
+
+#ifndef USB6FIRE_CONTROL_H
+#define USB6FIRE_CONTROL_H
+
+#include "common.h"
+
+enum {
+	CONTROL_MAX_ELEMENTS = 32
+};
+
+enum {
+	CONTROL_RATE_44KHZ,
+	CONTROL_RATE_48KHZ,
+	CONTROL_RATE_88KHZ,
+	CONTROL_RATE_96KHZ,
+	CONTROL_RATE_176KHZ,
+	CONTROL_RATE_192KHZ,
+	CONTROL_N_RATES
+};
+
+struct control_runtime {
+	int (*update_streaming)(struct control_runtime *rt);
+	int (*set_rate)(struct control_runtime *rt, int rate);
+	int (*set_channels)(struct control_runtime *rt, int n_analog_out,
+		int n_analog_in, bool spdif_out, bool spdif_in);
+
+	struct sfire_chip *chip;
+
+	struct snd_kcontrol *element[CONTROL_MAX_ELEMENTS];
+	bool opt_coax_switch;
+	bool line_phono_switch;
+	bool digital_thru_switch;
+	bool usb_streaming;
+	u8 output_vol[6];
+	u8 ovol_updated;
+	u8 output_mute;
+	s8 input_vol[2];
+	u8 ivol_updated;
+};
+
+int usb6fire_control_init(struct sfire_chip *chip);
+void usb6fire_control_abort(struct sfire_chip *chip);
+void usb6fire_control_destroy(struct sfire_chip *chip);
+#endif /* USB6FIRE_CONTROL_H */
+