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, 242 insertions, 0 deletions

diff --git a/drivers/media/dvb-frontends/stb6000.c b/drivers/media/dvb-frontends/stb6000.c
new file mode 100644
index 000000000..c66d4ac17
--- /dev/null
+++ b/drivers/media/dvb-frontends/stb6000.c
@@ -0,0 +1,242 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+  /*
+     Driver for ST STB6000 DVBS Silicon tuner
+
+     Copyright (C) 2008 Igor M. Liplianin (liplianin@me.by)
+
+
+  */
+
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <linux/dvb/frontend.h>
+#include <asm/types.h>
+
+#include "stb6000.h"
+
+static int debug;
+#define dprintk(args...) \
+	do { \
+		if (debug) \
+			printk(KERN_DEBUG "stb6000: " args); \
+	} while (0)
+
+struct stb6000_priv {
+	/* i2c details */
+	int i2c_address;
+	struct i2c_adapter *i2c;
+	u32 frequency;
+};
+
+static void stb6000_release(struct dvb_frontend *fe)
+{
+	kfree(fe->tuner_priv);
+	fe->tuner_priv = NULL;
+}
+
+static int stb6000_sleep(struct dvb_frontend *fe)
+{
+	struct stb6000_priv *priv = fe->tuner_priv;
+	int ret;
+	u8 buf[] = { 10, 0 };
+	struct i2c_msg msg = {
+		.addr = priv->i2c_address,
+		.flags = 0,
+		.buf = buf,
+		.len = 2
+	};
+
+	dprintk("%s:\n", __func__);
+
+	if (fe->ops.i2c_gate_ctrl)
+		fe->ops.i2c_gate_ctrl(fe, 1);
+
+	ret = i2c_transfer(priv->i2c, &msg, 1);
+	if (ret != 1)
+		dprintk("%s: i2c error\n", __func__);
+
+	if (fe->ops.i2c_gate_ctrl)
+		fe->ops.i2c_gate_ctrl(fe, 0);
+
+	return (ret == 1) ? 0 : ret;
+}
+
+static int stb6000_set_params(struct dvb_frontend *fe)
+{
+	struct dtv_frontend_properties *p = &fe->dtv_property_cache;
+	struct stb6000_priv *priv = fe->tuner_priv;
+	unsigned int n, m;
+	int ret;
+	u32 freq_mhz;
+	int bandwidth;
+	u8 buf[12];
+	struct i2c_msg msg = {
+		.addr = priv->i2c_address,
+		.flags = 0,
+		.buf = buf,
+		.len = 12
+	};
+
+	dprintk("%s:\n", __func__);
+
+	freq_mhz = p->frequency / 1000;
+	bandwidth = p->symbol_rate / 1000000;
+
+	if (bandwidth > 31)
+		bandwidth = 31;
+
+	if ((freq_mhz > 949) && (freq_mhz < 2151)) {
+		buf[0] = 0x01;
+		buf[1] = 0xac;
+		if (freq_mhz < 1950)
+			buf[1] = 0xaa;
+		if (freq_mhz < 1800)
+			buf[1] = 0xa8;
+		if (freq_mhz < 1650)
+			buf[1] = 0xa6;
+		if (freq_mhz < 1530)
+			buf[1] = 0xa5;
+		if (freq_mhz < 1470)
+			buf[1] = 0xa4;
+		if (freq_mhz < 1370)
+			buf[1] = 0xa2;
+		if (freq_mhz < 1300)
+			buf[1] = 0xa1;
+		if (freq_mhz < 1200)
+			buf[1] = 0xa0;
+		if (freq_mhz < 1075)
+			buf[1] = 0xbc;
+		if (freq_mhz < 1000)
+			buf[1] = 0xba;
+		if (freq_mhz < 1075) {
+			n = freq_mhz / 8; /* vco=lo*4 */
+			m = 2;
+		} else {
+			n = freq_mhz / 16; /* vco=lo*2 */
+			m = 1;
+		}
+		buf[2] = n >> 1;
+		buf[3] = (unsigned char)(((n & 1) << 7) |
+					(m * freq_mhz - n * 16) | 0x60);
+		buf[4] = 0x04;
+		buf[5] = 0x0e;
+
+		buf[6] = (unsigned char)(bandwidth);
+
+		buf[7] = 0xd8;
+		buf[8] = 0xd0;
+		buf[9] = 0x50;
+		buf[10] = 0xeb;
+		buf[11] = 0x4f;
+
+		if (fe->ops.i2c_gate_ctrl)
+			fe->ops.i2c_gate_ctrl(fe, 1);
+
+		ret = i2c_transfer(priv->i2c, &msg, 1);
+		if (ret != 1)
+			dprintk("%s: i2c error\n", __func__);
+
+		udelay(10);
+		if (fe->ops.i2c_gate_ctrl)
+			fe->ops.i2c_gate_ctrl(fe, 0);
+
+		buf[0] = 0x07;
+		buf[1] = 0xdf;
+		buf[2] = 0xd0;
+		buf[3] = 0x50;
+		buf[4] = 0xfb;
+		msg.len = 5;
+
+		if (fe->ops.i2c_gate_ctrl)
+			fe->ops.i2c_gate_ctrl(fe, 1);
+
+		ret = i2c_transfer(priv->i2c, &msg, 1);
+		if (ret != 1)
+			dprintk("%s: i2c error\n", __func__);
+
+		udelay(10);
+		if (fe->ops.i2c_gate_ctrl)
+			fe->ops.i2c_gate_ctrl(fe, 0);
+
+		priv->frequency = freq_mhz * 1000;
+
+		return (ret == 1) ? 0 : ret;
+	}
+	return -1;
+}
+
+static int stb6000_get_frequency(struct dvb_frontend *fe, u32 *frequency)
+{
+	struct stb6000_priv *priv = fe->tuner_priv;
+	*frequency = priv->frequency;
+	return 0;
+}
+
+static const struct dvb_tuner_ops stb6000_tuner_ops = {
+	.info = {
+		.name = "ST STB6000",
+		.frequency_min_hz =  950 * MHz,
+		.frequency_max_hz = 2150 * MHz
+	},
+	.release = stb6000_release,
+	.sleep = stb6000_sleep,
+	.set_params = stb6000_set_params,
+	.get_frequency = stb6000_get_frequency,
+};
+
+struct dvb_frontend *stb6000_attach(struct dvb_frontend *fe, int addr,
+						struct i2c_adapter *i2c)
+{
+	struct stb6000_priv *priv = NULL;
+	u8 b0[] = { 0 };
+	u8 b1[] = { 0, 0 };
+	struct i2c_msg msg[2] = {
+		{
+			.addr = addr,
+			.flags = 0,
+			.buf = b0,
+			.len = 0
+		}, {
+			.addr = addr,
+			.flags = I2C_M_RD,
+			.buf = b1,
+			.len = 2
+		}
+	};
+	int ret;
+
+	dprintk("%s:\n", __func__);
+
+	if (fe->ops.i2c_gate_ctrl)
+		fe->ops.i2c_gate_ctrl(fe, 1);
+
+	/* is some i2c device here ? */
+	ret = i2c_transfer(i2c, msg, 2);
+	if (fe->ops.i2c_gate_ctrl)
+		fe->ops.i2c_gate_ctrl(fe, 0);
+
+	if (ret != 2)
+		return NULL;
+
+	priv = kzalloc_obj(struct stb6000_priv);
+	if (priv == NULL)
+		return NULL;
+
+	priv->i2c_address = addr;
+	priv->i2c = i2c;
+
+	memcpy(&fe->ops.tuner_ops, &stb6000_tuner_ops,
+				sizeof(struct dvb_tuner_ops));
+
+	fe->tuner_priv = priv;
+
+	return fe;
+}
+EXPORT_SYMBOL_GPL(stb6000_attach);
+
+module_param(debug, int, 0644);
+MODULE_PARM_DESC(debug, "Turn on/off frontend debugging (default:off).");
+
+MODULE_DESCRIPTION("DVB STB6000 driver");
+MODULE_AUTHOR("Igor M. Liplianin <liplianin@me.by>");
+MODULE_LICENSE("GPL");