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, 104 insertions, 0 deletions

diff --git a/drivers/mfd/da9052-spi.c b/drivers/mfd/da9052-spi.c
new file mode 100644
index 000000000..29cf2c17f
--- /dev/null
+++ b/drivers/mfd/da9052-spi.c
@@ -0,0 +1,104 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * SPI access for Dialog DA9052 PMICs.
+ *
+ * Copyright(c) 2011 Dialog Semiconductor Ltd.
+ *
+ * Author: David Dajun Chen <dchen@diasemi.com>
+ */
+
+#include <linux/device.h>
+#include <linux/module.h>
+#include <linux/input.h>
+#include <linux/mfd/core.h>
+#include <linux/spi/spi.h>
+#include <linux/err.h>
+
+#include <linux/mfd/da9052/da9052.h>
+
+static int da9052_spi_probe(struct spi_device *spi)
+{
+	struct regmap_config config;
+	int ret;
+	const struct spi_device_id *id = spi_get_device_id(spi);
+	struct da9052 *da9052;
+
+	da9052 = devm_kzalloc(&spi->dev, sizeof(struct da9052), GFP_KERNEL);
+	if (!da9052)
+		return -ENOMEM;
+
+	spi->mode = SPI_MODE_0;
+	spi->bits_per_word = 8;
+	spi_setup(spi);
+
+	da9052->dev = &spi->dev;
+	da9052->chip_irq = spi->irq;
+
+	spi_set_drvdata(spi, da9052);
+
+	config = da9052_regmap_config;
+	config.read_flag_mask = 1;
+	config.reg_bits = 7;
+	config.pad_bits = 1;
+	config.val_bits = 8;
+	config.use_single_read = true;
+	config.use_single_write = true;
+
+	da9052->regmap = devm_regmap_init_spi(spi, &config);
+	if (IS_ERR(da9052->regmap)) {
+		ret = PTR_ERR(da9052->regmap);
+		dev_err(&spi->dev, "Failed to allocate register map: %d\n",
+			ret);
+		return ret;
+	}
+
+	return da9052_device_init(da9052, id->driver_data);
+}
+
+static void da9052_spi_remove(struct spi_device *spi)
+{
+	struct da9052 *da9052 = spi_get_drvdata(spi);
+
+	da9052_device_exit(da9052);
+}
+
+static const struct spi_device_id da9052_spi_id[] = {
+	{ .name = "da9052", .driver_data = DA9052 },
+	{ .name = "da9053-aa", .driver_data = DA9053_AA },
+	{ .name = "da9053-ba", .driver_data = DA9053_BA },
+	{ .name = "da9053-bb", .driver_data = DA9053_BB },
+	{ .name = "da9053-bc", .driver_data = DA9053_BC },
+	{ }
+};
+
+static struct spi_driver da9052_spi_driver = {
+	.probe = da9052_spi_probe,
+	.remove = da9052_spi_remove,
+	.id_table = da9052_spi_id,
+	.driver = {
+		.name = "da9052",
+	},
+};
+
+static int __init da9052_spi_init(void)
+{
+	int ret;
+
+	ret = spi_register_driver(&da9052_spi_driver);
+	if (ret != 0) {
+		pr_err("Failed to register DA9052 SPI driver, %d\n", ret);
+		return ret;
+	}
+
+	return 0;
+}
+subsys_initcall(da9052_spi_init);
+
+static void __exit da9052_spi_exit(void)
+{
+	spi_unregister_driver(&da9052_spi_driver);
+}
+module_exit(da9052_spi_exit);
+
+MODULE_AUTHOR("David Dajun Chen <dchen@diasemi.com>");
+MODULE_DESCRIPTION("SPI driver for Dialog DA9052 PMIC");