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, 49 insertions, 0 deletions

diff --git a/drivers/media/dvb-frontends/rtl2832.h b/drivers/media/dvb-frontends/rtl2832.h
new file mode 100644
index 000000000..85a8064bf
--- /dev/null
+++ b/drivers/media/dvb-frontends/rtl2832.h
@@ -0,0 +1,49 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Realtek RTL2832 DVB-T demodulator driver
+ *
+ * Copyright (C) 2012 Thomas Mair <thomas.mair86@gmail.com>
+ * Copyright (C) 2012-2014 Antti Palosaari <crope@iki.fi>
+ */
+
+#ifndef RTL2832_H
+#define RTL2832_H
+
+#include <linux/dvb/frontend.h>
+#include <linux/i2c-mux.h>
+
+/**
+ * struct rtl2832_platform_data - Platform data for the rtl2832 driver
+ * @clk: Clock frequency (4000000, 16000000, 25000000, 28800000).
+ * @tuner: Used tuner model.
+ * @get_dvb_frontend: Get DVB frontend.
+ * @get_i2c_adapter: Get I2C adapter.
+ * @slave_ts_ctrl: Control slave TS interface.
+ * @pid_filter: Set PID to PID filter.
+ * @pid_filter_ctrl: Control PID filter.
+ */
+struct rtl2832_platform_data {
+	u32 clk;
+	/*
+	 * XXX: This list must be kept sync with dvb_usb_rtl28xxu USB IF driver.
+	 */
+#define RTL2832_TUNER_FC2580    0x21
+#define RTL2832_TUNER_TUA9001   0x24
+#define RTL2832_TUNER_FC0012    0x26
+#define RTL2832_TUNER_E4000     0x27
+#define RTL2832_TUNER_FC0013    0x29
+#define RTL2832_TUNER_R820T     0x2a
+#define RTL2832_TUNER_R828D     0x2b
+#define RTL2832_TUNER_SI2157    0x2c
+	u8 tuner;
+
+	struct dvb_frontend* (*get_dvb_frontend)(struct i2c_client *);
+	struct i2c_adapter* (*get_i2c_adapter)(struct i2c_client *);
+	int (*slave_ts_ctrl)(struct i2c_client *, bool);
+	int (*pid_filter)(struct dvb_frontend *, u8, u16, int);
+	int (*pid_filter_ctrl)(struct dvb_frontend *, int);
+/* private: Register access for SDR module use only */
+	struct regmap *regmap;
+};
+
+#endif /* RTL2832_H */