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, 296 insertions, 0 deletions

diff --git a/drivers/media/dvb-frontends/isl6423.c b/drivers/media/dvb-frontends/isl6423.c
new file mode 100644
index 000000000..48f15cca0
--- /dev/null
+++ b/drivers/media/dvb-frontends/isl6423.c
@@ -0,0 +1,296 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+	Intersil ISL6423 SEC and LNB Power supply controller
+
+	Copyright (C) Manu Abraham <abraham.manu@gmail.com>
+
+*/
+
+#include <linux/delay.h>
+#include <linux/errno.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/string.h>
+#include <linux/slab.h>
+
+#include <media/dvb_frontend.h>
+#include "isl6423.h"
+
+static unsigned int verbose;
+module_param(verbose, int, 0644);
+MODULE_PARM_DESC(verbose, "Set Verbosity level");
+
+#define FE_ERROR				0
+#define FE_NOTICE				1
+#define FE_INFO					2
+#define FE_DEBUG				3
+#define FE_DEBUGREG				4
+
+#define dprintk(__y, __z, format, arg...) do {						\
+	if (__z) {									\
+		if	((verbose > FE_ERROR) && (verbose > __y))			\
+			printk(KERN_ERR "%s: " format "\n", __func__ , ##arg);		\
+		else if	((verbose > FE_NOTICE) && (verbose > __y))			\
+			printk(KERN_NOTICE "%s: " format "\n", __func__ , ##arg);	\
+		else if ((verbose > FE_INFO) && (verbose > __y))			\
+			printk(KERN_INFO "%s: " format "\n", __func__ , ##arg);		\
+		else if ((verbose > FE_DEBUG) && (verbose > __y))			\
+			printk(KERN_DEBUG "%s: " format "\n", __func__ , ##arg);	\
+	} else {									\
+		if (verbose > __y)							\
+			printk(format, ##arg);						\
+	}										\
+} while (0)
+
+struct isl6423_dev {
+	const struct isl6423_config	*config;
+	struct i2c_adapter		*i2c;
+
+	u8 reg_3;
+	u8 reg_4;
+
+	unsigned int verbose;
+};
+
+static int isl6423_write(struct isl6423_dev *isl6423, u8 reg)
+{
+	struct i2c_adapter *i2c = isl6423->i2c;
+	u8 addr			= isl6423->config->addr;
+	int err = 0;
+
+	struct i2c_msg msg = { .addr = addr, .flags = 0, .buf = &reg, .len = 1 };
+
+	dprintk(FE_DEBUG, 1, "write reg %02X", reg);
+	err = i2c_transfer(i2c, &msg, 1);
+	if (err < 0)
+		goto exit;
+	return 0;
+
+exit:
+	dprintk(FE_ERROR, 1, "I/O error <%d>", err);
+	return err;
+}
+
+static int isl6423_set_modulation(struct dvb_frontend *fe)
+{
+	struct isl6423_dev *isl6423		= (struct isl6423_dev *) fe->sec_priv;
+	const struct isl6423_config *config	= isl6423->config;
+	int err = 0;
+	u8 reg_2 = 0;
+
+	reg_2 = 0x01 << 5;
+
+	if (config->mod_extern)
+		reg_2 |= (1 << 3);
+	else
+		reg_2 |= (1 << 4);
+
+	err = isl6423_write(isl6423, reg_2);
+	if (err < 0)
+		goto exit;
+	return 0;
+
+exit:
+	dprintk(FE_ERROR, 1, "I/O error <%d>", err);
+	return err;
+}
+
+static int isl6423_voltage_boost(struct dvb_frontend *fe, long arg)
+{
+	struct isl6423_dev *isl6423 = (struct isl6423_dev *) fe->sec_priv;
+	u8 reg_3 = isl6423->reg_3;
+	u8 reg_4 = isl6423->reg_4;
+	int err = 0;
+
+	if (arg) {
+		/* EN = 1, VSPEN = 1, VBOT = 1 */
+		reg_4 |= (1 << 4);
+		reg_4 |= 0x1;
+		reg_3 |= (1 << 3);
+	} else {
+		/* EN = 1, VSPEN = 1, VBOT = 0 */
+		reg_4 |= (1 << 4);
+		reg_4 &= ~0x1;
+		reg_3 |= (1 << 3);
+	}
+	err = isl6423_write(isl6423, reg_3);
+	if (err < 0)
+		goto exit;
+
+	err = isl6423_write(isl6423, reg_4);
+	if (err < 0)
+		goto exit;
+
+	isl6423->reg_3 = reg_3;
+	isl6423->reg_4 = reg_4;
+
+	return 0;
+exit:
+	dprintk(FE_ERROR, 1, "I/O error <%d>", err);
+	return err;
+}
+
+
+static int isl6423_set_voltage(struct dvb_frontend *fe,
+			       enum fe_sec_voltage voltage)
+{
+	struct isl6423_dev *isl6423 = (struct isl6423_dev *) fe->sec_priv;
+	u8 reg_3 = isl6423->reg_3;
+	u8 reg_4 = isl6423->reg_4;
+	int err = 0;
+
+	switch (voltage) {
+	case SEC_VOLTAGE_OFF:
+		/* EN = 0 */
+		reg_4 &= ~(1 << 4);
+		break;
+
+	case SEC_VOLTAGE_13:
+		/* EN = 1, VSPEN = 1, VTOP = 0, VBOT = 0 */
+		reg_4 |= (1 << 4);
+		reg_4 &= ~0x3;
+		reg_3 |= (1 << 3);
+		break;
+
+	case SEC_VOLTAGE_18:
+		/* EN = 1, VSPEN = 1, VTOP = 1, VBOT = 0 */
+		reg_4 |= (1 << 4);
+		reg_4 |=  0x2;
+		reg_4 &= ~0x1;
+		reg_3 |= (1 << 3);
+		break;
+
+	default:
+		break;
+	}
+	err = isl6423_write(isl6423, reg_3);
+	if (err < 0)
+		goto exit;
+
+	err = isl6423_write(isl6423, reg_4);
+	if (err < 0)
+		goto exit;
+
+	isl6423->reg_3 = reg_3;
+	isl6423->reg_4 = reg_4;
+
+	return 0;
+exit:
+	dprintk(FE_ERROR, 1, "I/O error <%d>", err);
+	return err;
+}
+
+static int isl6423_set_current(struct dvb_frontend *fe)
+{
+	struct isl6423_dev *isl6423		= (struct isl6423_dev *) fe->sec_priv;
+	u8 reg_3 = isl6423->reg_3;
+	const struct isl6423_config *config	= isl6423->config;
+	int err = 0;
+
+	switch (config->current_max) {
+	case SEC_CURRENT_275m:
+		/* 275mA */
+		/* ISELH = 0, ISELL = 0 */
+		reg_3 &= ~0x3;
+		break;
+
+	case SEC_CURRENT_515m:
+		/* 515mA */
+		/* ISELH = 0, ISELL = 1 */
+		reg_3 &= ~0x2;
+		reg_3 |=  0x1;
+		break;
+
+	case SEC_CURRENT_635m:
+		/* 635mA */
+		/* ISELH = 1, ISELL = 0 */
+		reg_3 &= ~0x1;
+		reg_3 |=  0x2;
+		break;
+
+	case SEC_CURRENT_800m:
+		/* 800mA */
+		/* ISELH = 1, ISELL = 1 */
+		reg_3 |= 0x3;
+		break;
+	}
+
+	err = isl6423_write(isl6423, reg_3);
+	if (err < 0)
+		goto exit;
+
+	switch (config->curlim) {
+	case SEC_CURRENT_LIM_ON:
+		/* DCL = 0 */
+		reg_3 &= ~0x10;
+		break;
+
+	case SEC_CURRENT_LIM_OFF:
+		/* DCL = 1 */
+		reg_3 |= 0x10;
+		break;
+	}
+
+	err = isl6423_write(isl6423, reg_3);
+	if (err < 0)
+		goto exit;
+
+	isl6423->reg_3 = reg_3;
+
+	return 0;
+exit:
+	dprintk(FE_ERROR, 1, "I/O error <%d>", err);
+	return err;
+}
+
+static void isl6423_release(struct dvb_frontend *fe)
+{
+	isl6423_set_voltage(fe, SEC_VOLTAGE_OFF);
+
+	kfree(fe->sec_priv);
+	fe->sec_priv = NULL;
+}
+
+struct dvb_frontend *isl6423_attach(struct dvb_frontend *fe,
+				    struct i2c_adapter *i2c,
+				    const struct isl6423_config *config)
+{
+	struct isl6423_dev *isl6423;
+
+	isl6423 = kzalloc_obj(struct isl6423_dev);
+	if (!isl6423)
+		return NULL;
+
+	isl6423->config	= config;
+	isl6423->i2c	= i2c;
+	fe->sec_priv	= isl6423;
+
+	/* SR3H = 0, SR3M = 1, SR3L = 0 */
+	isl6423->reg_3 = 0x02 << 5;
+	/* SR4H = 0, SR4M = 1, SR4L = 1 */
+	isl6423->reg_4 = 0x03 << 5;
+
+	if (isl6423_set_current(fe))
+		goto exit;
+
+	if (isl6423_set_modulation(fe))
+		goto exit;
+
+	fe->ops.release_sec		= isl6423_release;
+	fe->ops.set_voltage		= isl6423_set_voltage;
+	fe->ops.enable_high_lnb_voltage = isl6423_voltage_boost;
+	isl6423->verbose		= verbose;
+
+	return fe;
+
+exit:
+	kfree(isl6423);
+	fe->sec_priv = NULL;
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(isl6423_attach);
+
+MODULE_DESCRIPTION("ISL6423 SEC");
+MODULE_AUTHOR("Manu Abraham");
+MODULE_LICENSE("GPL");