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, 246 insertions, 0 deletions

diff --git a/drivers/mfd/lp8788.c b/drivers/mfd/lp8788.c
new file mode 100644
index 000000000..32f255378
--- /dev/null
+++ b/drivers/mfd/lp8788.c
@@ -0,0 +1,246 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * TI LP8788 MFD - core interface
+ *
+ * Copyright 2012 Texas Instruments
+ *
+ * Author: Milo(Woogyom) Kim <milo.kim@ti.com>
+ */
+
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/mfd/core.h>
+#include <linux/mfd/lp8788.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+
+#define MAX_LP8788_REGISTERS		0xA2
+
+#define MFD_DEV_SIMPLE(_name)					\
+{								\
+	.name = LP8788_DEV_##_name,				\
+}
+
+#define MFD_DEV_WITH_ID(_name, _id)				\
+{								\
+	.name = LP8788_DEV_##_name,				\
+	.id = _id,						\
+}
+
+#define MFD_DEV_WITH_RESOURCE(_name, _resource, num_resource)	\
+{								\
+	.name = LP8788_DEV_##_name,				\
+	.resources = _resource,					\
+	.num_resources = num_resource,				\
+}
+
+static const struct resource chg_irqs[] = {
+	/* Charger Interrupts */
+	{
+		.start = LP8788_INT_CHG_INPUT_STATE,
+		.end   = LP8788_INT_PRECHG_TIMEOUT,
+		.name  = LP8788_CHG_IRQ,
+		.flags = IORESOURCE_IRQ,
+	},
+	/* Power Routing Switch Interrupts */
+	{
+		.start = LP8788_INT_ENTER_SYS_SUPPORT,
+		.end   = LP8788_INT_EXIT_SYS_SUPPORT,
+		.name  = LP8788_PRSW_IRQ,
+		.flags = IORESOURCE_IRQ,
+	},
+	/* Battery Interrupts */
+	{
+		.start = LP8788_INT_BATT_LOW,
+		.end   = LP8788_INT_NO_BATT,
+		.name  = LP8788_BATT_IRQ,
+		.flags = IORESOURCE_IRQ,
+	},
+};
+
+static const struct resource rtc_irqs[] = {
+	{
+		.start = LP8788_INT_RTC_ALARM1,
+		.end   = LP8788_INT_RTC_ALARM2,
+		.name  = LP8788_ALM_IRQ,
+		.flags = IORESOURCE_IRQ,
+	},
+};
+
+static const struct mfd_cell lp8788_devs[] = {
+	/* 4 bucks */
+	MFD_DEV_WITH_ID(BUCK, 1),
+	MFD_DEV_WITH_ID(BUCK, 2),
+	MFD_DEV_WITH_ID(BUCK, 3),
+	MFD_DEV_WITH_ID(BUCK, 4),
+
+	/* 12 digital ldos */
+	MFD_DEV_WITH_ID(DLDO, 1),
+	MFD_DEV_WITH_ID(DLDO, 2),
+	MFD_DEV_WITH_ID(DLDO, 3),
+	MFD_DEV_WITH_ID(DLDO, 4),
+	MFD_DEV_WITH_ID(DLDO, 5),
+	MFD_DEV_WITH_ID(DLDO, 6),
+	MFD_DEV_WITH_ID(DLDO, 7),
+	MFD_DEV_WITH_ID(DLDO, 8),
+	MFD_DEV_WITH_ID(DLDO, 9),
+	MFD_DEV_WITH_ID(DLDO, 10),
+	MFD_DEV_WITH_ID(DLDO, 11),
+	MFD_DEV_WITH_ID(DLDO, 12),
+
+	/* 10 analog ldos */
+	MFD_DEV_WITH_ID(ALDO, 1),
+	MFD_DEV_WITH_ID(ALDO, 2),
+	MFD_DEV_WITH_ID(ALDO, 3),
+	MFD_DEV_WITH_ID(ALDO, 4),
+	MFD_DEV_WITH_ID(ALDO, 5),
+	MFD_DEV_WITH_ID(ALDO, 6),
+	MFD_DEV_WITH_ID(ALDO, 7),
+	MFD_DEV_WITH_ID(ALDO, 8),
+	MFD_DEV_WITH_ID(ALDO, 9),
+	MFD_DEV_WITH_ID(ALDO, 10),
+
+	/* ADC */
+	MFD_DEV_SIMPLE(ADC),
+
+	/* battery charger */
+	MFD_DEV_WITH_RESOURCE(CHARGER, chg_irqs, ARRAY_SIZE(chg_irqs)),
+
+	/* rtc */
+	MFD_DEV_WITH_RESOURCE(RTC, rtc_irqs, ARRAY_SIZE(rtc_irqs)),
+
+	/* backlight */
+	MFD_DEV_SIMPLE(BACKLIGHT),
+
+	/* current sink for vibrator */
+	MFD_DEV_SIMPLE(VIBRATOR),
+
+	/* current sink for keypad LED */
+	MFD_DEV_SIMPLE(KEYLED),
+};
+
+int lp8788_read_byte(struct lp8788 *lp, u8 reg, u8 *data)
+{
+	int ret;
+	unsigned int val;
+
+	ret = regmap_read(lp->regmap, reg, &val);
+	if (ret < 0) {
+		dev_err(lp->dev, "failed to read 0x%.2x\n", reg);
+		return ret;
+	}
+
+	*data = (u8)val;
+	return 0;
+}
+EXPORT_SYMBOL_GPL(lp8788_read_byte);
+
+int lp8788_read_multi_bytes(struct lp8788 *lp, u8 reg, u8 *data, size_t count)
+{
+	return regmap_bulk_read(lp->regmap, reg, data, count);
+}
+EXPORT_SYMBOL_GPL(lp8788_read_multi_bytes);
+
+int lp8788_write_byte(struct lp8788 *lp, u8 reg, u8 data)
+{
+	return regmap_write(lp->regmap, reg, data);
+}
+EXPORT_SYMBOL_GPL(lp8788_write_byte);
+
+int lp8788_update_bits(struct lp8788 *lp, u8 reg, u8 mask, u8 data)
+{
+	return regmap_update_bits(lp->regmap, reg, mask, data);
+}
+EXPORT_SYMBOL_GPL(lp8788_update_bits);
+
+static int lp8788_platform_init(struct lp8788 *lp)
+{
+	struct lp8788_platform_data *pdata = lp->pdata;
+
+	return (pdata && pdata->init_func) ? pdata->init_func(lp) : 0;
+}
+
+static const struct regmap_config lp8788_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+	.max_register = MAX_LP8788_REGISTERS,
+};
+
+static int lp8788_probe(struct i2c_client *cl)
+{
+	struct lp8788 *lp;
+	struct lp8788_platform_data *pdata = dev_get_platdata(&cl->dev);
+	int ret;
+
+	lp = devm_kzalloc(&cl->dev, sizeof(struct lp8788), GFP_KERNEL);
+	if (!lp)
+		return -ENOMEM;
+
+	lp->regmap = devm_regmap_init_i2c(cl, &lp8788_regmap_config);
+	if (IS_ERR(lp->regmap)) {
+		ret = PTR_ERR(lp->regmap);
+		dev_err(&cl->dev, "regmap init i2c err: %d\n", ret);
+		return ret;
+	}
+
+	lp->pdata = pdata;
+	lp->dev = &cl->dev;
+	i2c_set_clientdata(cl, lp);
+
+	ret = lp8788_platform_init(lp);
+	if (ret)
+		return ret;
+
+	ret = lp8788_irq_init(lp, cl->irq);
+	if (ret)
+		return ret;
+
+	ret = mfd_add_devices(lp->dev, -1, lp8788_devs,
+			      ARRAY_SIZE(lp8788_devs), NULL, 0, NULL);
+	if (ret)
+		goto err_exit_irq;
+
+	return 0;
+
+err_exit_irq:
+	lp8788_irq_exit(lp);
+	return ret;
+}
+
+static void lp8788_remove(struct i2c_client *cl)
+{
+	struct lp8788 *lp = i2c_get_clientdata(cl);
+
+	mfd_remove_devices(lp->dev);
+	lp8788_irq_exit(lp);
+}
+
+static const struct i2c_device_id lp8788_ids[] = {
+	{ "lp8788" },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, lp8788_ids);
+
+static struct i2c_driver lp8788_driver = {
+	.driver = {
+		.name = "lp8788",
+	},
+	.probe = lp8788_probe,
+	.remove = lp8788_remove,
+	.id_table = lp8788_ids,
+};
+
+static int __init lp8788_init(void)
+{
+	return i2c_add_driver(&lp8788_driver);
+}
+subsys_initcall(lp8788_init);
+
+static void __exit lp8788_exit(void)
+{
+	i2c_del_driver(&lp8788_driver);
+}
+module_exit(lp8788_exit);
+
+MODULE_DESCRIPTION("TI LP8788 MFD Driver");
+MODULE_AUTHOR("Milo Kim");