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, 134 insertions, 0 deletions

diff --git a/drivers/mfd/ac100.c b/drivers/mfd/ac100.c
new file mode 100644
index 000000000..8f47c392c
--- /dev/null
+++ b/drivers/mfd/ac100.c
@@ -0,0 +1,134 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * MFD core driver for X-Powers' AC100 Audio Codec IC
+ *
+ * The AC100 is a highly integrated audio codec and RTC subsystem designed
+ * for mobile applications. It has 3 I2S/PCM interfaces, a 2 channel DAC,
+ * a 2 channel ADC with 5 inputs and a builtin mixer. The RTC subsystem has
+ * 3 clock outputs.
+ *
+ * The audio codec and RTC parts are completely separate, sharing only the
+ * host interface for access to its registers.
+ *
+ * Copyright (2016) Chen-Yu Tsai
+ *
+ * Author: Chen-Yu Tsai <wens@csie.org>
+ */
+
+#include <linux/interrupt.h>
+#include <linux/kernel.h>
+#include <linux/mfd/core.h>
+#include <linux/mfd/ac100.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/regmap.h>
+#include <linux/sunxi-rsb.h>
+
+static const struct regmap_range ac100_writeable_ranges[] = {
+	regmap_reg_range(AC100_CHIP_AUDIO_RST, AC100_I2S_SR_CTRL),
+	regmap_reg_range(AC100_I2S1_CLK_CTRL, AC100_I2S1_MXR_GAIN),
+	regmap_reg_range(AC100_I2S2_CLK_CTRL, AC100_I2S2_MXR_GAIN),
+	regmap_reg_range(AC100_I2S3_CLK_CTRL, AC100_I2S3_SIG_PATH_CTRL),
+	regmap_reg_range(AC100_ADC_DIG_CTRL, AC100_ADC_VOL_CTRL),
+	regmap_reg_range(AC100_HMIC_CTRL1, AC100_HMIC_STATUS),
+	regmap_reg_range(AC100_DAC_DIG_CTRL, AC100_DAC_MXR_GAIN),
+	regmap_reg_range(AC100_ADC_APC_CTRL, AC100_LINEOUT_CTRL),
+	regmap_reg_range(AC100_ADC_DAP_L_CTRL, AC100_ADC_DAP_OPT),
+	regmap_reg_range(AC100_DAC_DAP_CTRL, AC100_DAC_DAP_OPT),
+	regmap_reg_range(AC100_ADC_DAP_ENA, AC100_DAC_DAP_ENA),
+	regmap_reg_range(AC100_SRC1_CTRL1, AC100_SRC1_CTRL2),
+	regmap_reg_range(AC100_SRC2_CTRL1, AC100_SRC2_CTRL2),
+	regmap_reg_range(AC100_CLK32K_ANALOG_CTRL, AC100_CLKOUT_CTRL3),
+	regmap_reg_range(AC100_RTC_RST, AC100_RTC_UPD),
+	regmap_reg_range(AC100_ALM_INT_ENA, AC100_ALM_INT_STA),
+	regmap_reg_range(AC100_ALM_SEC, AC100_RTC_GP(15)),
+};
+
+static const struct regmap_range ac100_volatile_ranges[] = {
+	regmap_reg_range(AC100_CHIP_AUDIO_RST, AC100_PLL_CTRL2),
+	regmap_reg_range(AC100_HMIC_STATUS, AC100_HMIC_STATUS),
+	regmap_reg_range(AC100_ADC_DAP_L_STA, AC100_ADC_DAP_L_STA),
+	regmap_reg_range(AC100_SRC1_CTRL1, AC100_SRC1_CTRL1),
+	regmap_reg_range(AC100_SRC1_CTRL3, AC100_SRC2_CTRL1),
+	regmap_reg_range(AC100_SRC2_CTRL3, AC100_SRC2_CTRL4),
+	regmap_reg_range(AC100_RTC_RST, AC100_RTC_RST),
+	regmap_reg_range(AC100_RTC_SEC, AC100_ALM_INT_STA),
+	regmap_reg_range(AC100_ALM_SEC, AC100_ALM_UPD),
+};
+
+static const struct regmap_access_table ac100_writeable_table = {
+	.yes_ranges	= ac100_writeable_ranges,
+	.n_yes_ranges	= ARRAY_SIZE(ac100_writeable_ranges),
+};
+
+static const struct regmap_access_table ac100_volatile_table = {
+	.yes_ranges	= ac100_volatile_ranges,
+	.n_yes_ranges	= ARRAY_SIZE(ac100_volatile_ranges),
+};
+
+static const struct regmap_config ac100_regmap_config = {
+	.reg_bits	= 8,
+	.val_bits	= 16,
+	.wr_table	= &ac100_writeable_table,
+	.volatile_table	= &ac100_volatile_table,
+	.max_register	= AC100_RTC_GP(15),
+	.cache_type	= REGCACHE_MAPLE,
+};
+
+static struct mfd_cell ac100_cells[] = {
+	{
+		.name		= "ac100-codec",
+		.of_compatible	= "x-powers,ac100-codec",
+	}, {
+		.name		= "ac100-rtc",
+		.of_compatible	= "x-powers,ac100-rtc",
+	},
+};
+
+static int ac100_rsb_probe(struct sunxi_rsb_device *rdev)
+{
+	struct ac100_dev *ac100;
+	int ret;
+
+	ac100 = devm_kzalloc(&rdev->dev, sizeof(*ac100), GFP_KERNEL);
+	if (!ac100)
+		return -ENOMEM;
+
+	ac100->dev = &rdev->dev;
+	sunxi_rsb_device_set_drvdata(rdev, ac100);
+
+	ac100->regmap = devm_regmap_init_sunxi_rsb(rdev, &ac100_regmap_config);
+	if (IS_ERR(ac100->regmap)) {
+		ret = PTR_ERR(ac100->regmap);
+		dev_err(ac100->dev, "regmap init failed: %d\n", ret);
+		return ret;
+	}
+
+	ret = devm_mfd_add_devices(ac100->dev, PLATFORM_DEVID_NONE, ac100_cells,
+				   ARRAY_SIZE(ac100_cells), NULL, 0, NULL);
+	if (ret) {
+		dev_err(ac100->dev, "failed to add MFD devices: %d\n", ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+static const struct of_device_id ac100_of_match[] = {
+	{ .compatible = "x-powers,ac100" },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, ac100_of_match);
+
+static struct sunxi_rsb_driver ac100_rsb_driver = {
+	.driver = {
+		.name	= "ac100",
+		.of_match_table	= of_match_ptr(ac100_of_match),
+	},
+	.probe	= ac100_rsb_probe,
+};
+module_sunxi_rsb_driver(ac100_rsb_driver);
+
+MODULE_DESCRIPTION("Audio codec MFD core driver for AC100");
+MODULE_AUTHOR("Chen-Yu Tsai <wens@csie.org>");
+MODULE_LICENSE("GPL v2");