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, 81 insertions, 0 deletions

diff --git a/drivers/media/dvb-frontends/dib3000mc.h b/drivers/media/dvb-frontends/dib3000mc.h
new file mode 100644
index 000000000..5ed3d9147
--- /dev/null
+++ b/drivers/media/dvb-frontends/dib3000mc.h
@@ -0,0 +1,81 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Driver for DiBcom DiB3000MC/P-demodulator.
+ *
+ * Copyright (C) 2004-6 DiBcom (http://www.dibcom.fr/)
+ * Copyright (C) 2004-5 Patrick Boettcher (patrick.boettcher@posteo.de)
+ *
+ * This code is partially based on the previous dib3000mc.c .
+ */
+#ifndef DIB3000MC_H
+#define DIB3000MC_H
+
+#include "dibx000_common.h"
+
+struct dib3000mc_config {
+	struct dibx000_agc_config *agc;
+
+	u8 phase_noise_mode;
+	u8 impulse_noise_mode;
+
+	u8  pwm3_inversion;
+	u8  use_pwm3;
+	u16 pwm3_value;
+
+	u16 max_time;
+	u16 ln_adc_level;
+
+	u8 agc_command1 :1;
+	u8 agc_command2 :1;
+
+	u8 mobile_mode;
+
+	u8 output_mpeg2_in_188_bytes;
+};
+
+#define DEFAULT_DIB3000MC_I2C_ADDRESS 16
+#define DEFAULT_DIB3000P_I2C_ADDRESS  24
+
+#if IS_REACHABLE(CONFIG_DVB_DIB3000MC)
+extern struct dvb_frontend *dib3000mc_attach(struct i2c_adapter *i2c_adap,
+					     u8 i2c_addr,
+					     struct dib3000mc_config *cfg);
+extern int dib3000mc_i2c_enumeration(struct i2c_adapter *i2c,
+				     int no_of_demods, u8 default_addr,
+				     struct dib3000mc_config cfg[]);
+extern
+struct i2c_adapter *dib3000mc_get_tuner_i2c_master(struct dvb_frontend *demod,
+						   int gating);
+#else
+static inline
+struct dvb_frontend *dib3000mc_attach(struct i2c_adapter *i2c_adap, u8 i2c_addr,
+				      struct dib3000mc_config *cfg)
+{
+	printk(KERN_WARNING "%s: driver disabled by Kconfig\n", __func__);
+	return NULL;
+}
+
+static inline
+int dib3000mc_i2c_enumeration(struct i2c_adapter *i2c,
+			      int no_of_demods, u8 default_addr,
+			      struct dib3000mc_config cfg[])
+{
+	printk(KERN_WARNING "%s: driver disabled by Kconfig\n", __func__);
+	return -ENODEV;
+}
+
+static inline
+struct i2c_adapter *dib3000mc_get_tuner_i2c_master(struct dvb_frontend *demod,
+						   int gating)
+{
+	printk(KERN_WARNING "%s: driver disabled by Kconfig\n", __func__);
+	return NULL;
+}
+#endif // CONFIG_DVB_DIB3000MC
+
+extern int dib3000mc_pid_control(struct dvb_frontend *fe, int index, int pid,int onoff);
+extern int dib3000mc_pid_parse(struct dvb_frontend *fe, int onoff);
+
+extern void dib3000mc_set_config(struct dvb_frontend *, struct dib3000mc_config *);
+
+#endif