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, 139 insertions, 0 deletions

diff --git a/drivers/hwmon/i5500_temp.c b/drivers/hwmon/i5500_temp.c
new file mode 100644
index 000000000..bf006cb27
--- /dev/null
+++ b/drivers/hwmon/i5500_temp.c
@@ -0,0 +1,139 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * i5500_temp - Driver for Intel 5500/5520/X58 chipset thermal sensor
+ *
+ * Copyright (C) 2012, 2014 Jean Delvare <jdelvare@suse.de>
+ */
+
+#include <linux/bitops.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/device.h>
+#include <linux/pci.h>
+#include <linux/hwmon.h>
+#include <linux/err.h>
+
+/* Register definitions from datasheet */
+#define REG_TSTHRCATA	0xE2
+#define REG_TSCTRL	0xE8
+#define REG_TSTHRRPEX	0xEB
+#define REG_TSTHRLO	0xEC
+#define REG_TSTHRHI	0xEE
+#define REG_CTHINT	0xF0
+#define REG_TSFSC	0xF3
+#define REG_CTSTS	0xF4
+#define REG_TSTHRRQPI	0xF5
+#define REG_CTCTRL	0xF7
+#define REG_TSTIMER	0xF8
+
+static int i5500_read(struct device *dev, enum hwmon_sensor_types type, u32 attr, int channel,
+		      long *val)
+{
+	struct pci_dev *pdev = to_pci_dev(dev->parent);
+	u16 tsthr;
+	s8 tsfsc;
+	u8 ctsts;
+
+	switch (type) {
+	case hwmon_temp:
+		switch (attr) {
+		/* Sensor resolution : 0.5 degree C */
+		case hwmon_temp_input:
+			pci_read_config_word(pdev, REG_TSTHRHI, &tsthr);
+			pci_read_config_byte(pdev, REG_TSFSC, &tsfsc);
+			*val = (tsthr - tsfsc) * 500;
+			return 0;
+		case hwmon_temp_max:
+			pci_read_config_word(pdev, REG_TSTHRHI, &tsthr);
+			*val = tsthr * 500;
+			return 0;
+		case hwmon_temp_max_hyst:
+			pci_read_config_word(pdev, REG_TSTHRLO, &tsthr);
+			*val = tsthr * 500;
+			return 0;
+		case hwmon_temp_crit:
+			pci_read_config_word(pdev, REG_TSTHRCATA, &tsthr);
+			*val = tsthr * 500;
+			return 0;
+		case hwmon_temp_max_alarm:
+			pci_read_config_byte(pdev, REG_CTSTS, &ctsts);
+			*val = !!(ctsts & BIT(1));
+			return 0;
+		case hwmon_temp_crit_alarm:
+			pci_read_config_byte(pdev, REG_CTSTS, &ctsts);
+			*val = !!(ctsts & BIT(0));
+			return 0;
+		default:
+			break;
+		}
+		break;
+	default:
+		break;
+	}
+
+	return -EOPNOTSUPP;
+}
+
+static const struct hwmon_ops i5500_ops = {
+	.visible = 0444,
+	.read = i5500_read,
+};
+
+static const struct hwmon_channel_info * const i5500_info[] = {
+	HWMON_CHANNEL_INFO(chip, HWMON_C_REGISTER_TZ),
+	HWMON_CHANNEL_INFO(temp,
+			   HWMON_T_INPUT | HWMON_T_MAX | HWMON_T_MAX_HYST | HWMON_T_CRIT |
+			   HWMON_T_MAX_ALARM | HWMON_T_CRIT_ALARM
+			   ),
+	NULL
+};
+
+static const struct hwmon_chip_info i5500_chip_info = {
+	.ops = &i5500_ops,
+	.info = i5500_info,
+};
+
+static const struct pci_device_id i5500_temp_ids[] = {
+	{ PCI_DEVICE(PCI_VENDOR_ID_INTEL, 0x3438) },
+	{ 0 },
+};
+
+MODULE_DEVICE_TABLE(pci, i5500_temp_ids);
+
+static int i5500_temp_probe(struct pci_dev *pdev,
+			    const struct pci_device_id *id)
+{
+	int err;
+	struct device *hwmon_dev;
+	u32 tstimer;
+	s8 tsfsc;
+
+	err = pcim_enable_device(pdev);
+	if (err) {
+		dev_err(&pdev->dev, "Failed to enable device\n");
+		return err;
+	}
+
+	pci_read_config_byte(pdev, REG_TSFSC, &tsfsc);
+	pci_read_config_dword(pdev, REG_TSTIMER, &tstimer);
+	if (tsfsc == 0x7F && tstimer == 0x07D30D40) {
+		dev_notice(&pdev->dev, "Sensor seems to be disabled\n");
+		return -ENODEV;
+	}
+
+	hwmon_dev = devm_hwmon_device_register_with_info(&pdev->dev, "intel5500", NULL,
+							 &i5500_chip_info, NULL);
+	return PTR_ERR_OR_ZERO(hwmon_dev);
+}
+
+static struct pci_driver i5500_temp_driver = {
+	.name = "i5500_temp",
+	.id_table = i5500_temp_ids,
+	.probe = i5500_temp_probe,
+};
+
+module_pci_driver(i5500_temp_driver);
+
+MODULE_AUTHOR("Jean Delvare <jdelvare@suse.de>");
+MODULE_DESCRIPTION("Intel 5500/5520/X58 chipset thermal sensor driver");
+MODULE_LICENSE("GPL");