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, 144 insertions, 0 deletions

diff --git a/drivers/acpi/fan_attr.c b/drivers/acpi/fan_attr.c
new file mode 100644
index 000000000..9b7fa52f3
--- /dev/null
+++ b/drivers/acpi/fan_attr.c
@@ -0,0 +1,144 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *  fan_attr.c - Create extra attributes for ACPI Fan driver
+ *
+ *  Copyright (C) 2001, 2002 Andy Grover <andrew.grover@intel.com>
+ *  Copyright (C) 2001, 2002 Paul Diefenbaugh <paul.s.diefenbaugh@intel.com>
+ *  Copyright (C) 2022 Intel Corporation. All rights reserved.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/acpi.h>
+
+#include "fan.h"
+
+MODULE_LICENSE("GPL");
+
+static ssize_t show_state(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	struct acpi_fan_fps *fps = container_of(attr, struct acpi_fan_fps, dev_attr);
+	int count;
+
+	if (fps->control == 0xFFFFFFFF || fps->control > 100)
+		count = sysfs_emit(buf, "not-defined:");
+	else
+		count = sysfs_emit(buf, "%lld:", fps->control);
+
+	if (fps->trip_point == 0xFFFFFFFF || fps->trip_point > 9)
+		count += sysfs_emit_at(buf, count, "not-defined:");
+	else
+		count += sysfs_emit_at(buf, count, "%lld:", fps->trip_point);
+
+	if (fps->speed == 0xFFFFFFFF)
+		count += sysfs_emit_at(buf, count, "not-defined:");
+	else
+		count += sysfs_emit_at(buf, count, "%lld:", fps->speed);
+
+	if (fps->noise_level == 0xFFFFFFFF)
+		count += sysfs_emit_at(buf, count, "not-defined:");
+	else
+		count += sysfs_emit_at(buf, count, "%lld:", fps->noise_level * 100);
+
+	if (fps->power == 0xFFFFFFFF)
+		count += sysfs_emit_at(buf, count, "not-defined\n");
+	else
+		count += sysfs_emit_at(buf, count, "%lld\n", fps->power);
+
+	return count;
+}
+
+static ssize_t show_fan_speed(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	struct acpi_device *acpi_dev = container_of(dev, struct acpi_device, dev);
+	struct acpi_fan_fst fst;
+	int status;
+
+	status = acpi_fan_get_fst(acpi_dev->handle, &fst);
+	if (status)
+		return status;
+
+	return sysfs_emit(buf, "%lld\n", fst.speed);
+}
+
+static ssize_t show_fine_grain_control(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	struct acpi_device *acpi_dev = container_of(dev, struct acpi_device, dev);
+	struct acpi_fan *fan = acpi_driver_data(acpi_dev);
+
+	return sysfs_emit(buf, "%d\n", fan->fif.fine_grain_ctrl);
+}
+
+int acpi_fan_create_attributes(struct acpi_device *device)
+{
+	struct acpi_fan *fan = acpi_driver_data(device);
+	int i, status;
+
+	/* _FST is present if we are here */
+	sysfs_attr_init(&fan->fst_speed.attr);
+	fan->fst_speed.show = show_fan_speed;
+	fan->fst_speed.store = NULL;
+	fan->fst_speed.attr.name = "fan_speed_rpm";
+	fan->fst_speed.attr.mode = 0444;
+	status = sysfs_create_file(&device->dev.kobj, &fan->fst_speed.attr);
+	if (status)
+		return status;
+
+	if (!fan->acpi4)
+		return 0;
+
+	sysfs_attr_init(&fan->fine_grain_control.attr);
+	fan->fine_grain_control.show = show_fine_grain_control;
+	fan->fine_grain_control.store = NULL;
+	fan->fine_grain_control.attr.name = "fine_grain_control";
+	fan->fine_grain_control.attr.mode = 0444;
+	status = sysfs_create_file(&device->dev.kobj, &fan->fine_grain_control.attr);
+	if (status)
+		goto rem_fst_attr;
+
+	for (i = 0; i < fan->fps_count; ++i) {
+		struct acpi_fan_fps *fps = &fan->fps[i];
+
+		snprintf(fps->name, ACPI_FPS_NAME_LEN, "state%d", i);
+		sysfs_attr_init(&fps->dev_attr.attr);
+		fps->dev_attr.show = show_state;
+		fps->dev_attr.store = NULL;
+		fps->dev_attr.attr.name = fps->name;
+		fps->dev_attr.attr.mode = 0444;
+		status = sysfs_create_file(&device->dev.kobj, &fps->dev_attr.attr);
+		if (status) {
+			int j;
+
+			for (j = 0; j < i; ++j)
+				sysfs_remove_file(&device->dev.kobj, &fan->fps[j].dev_attr.attr);
+			goto rem_fine_grain_attr;
+		}
+	}
+
+	return 0;
+
+rem_fine_grain_attr:
+	sysfs_remove_file(&device->dev.kobj, &fan->fine_grain_control.attr);
+
+rem_fst_attr:
+	sysfs_remove_file(&device->dev.kobj, &fan->fst_speed.attr);
+
+	return status;
+}
+
+void acpi_fan_delete_attributes(struct acpi_device *device)
+{
+	struct acpi_fan *fan = acpi_driver_data(device);
+	int i;
+
+	sysfs_remove_file(&device->dev.kobj, &fan->fst_speed.attr);
+
+	if (!fan->acpi4)
+		return;
+
+	for (i = 0; i < fan->fps_count; ++i)
+		sysfs_remove_file(&device->dev.kobj, &fan->fps[i].dev_attr.attr);
+
+	sysfs_remove_file(&device->dev.kobj, &fan->fine_grain_control.attr);
+}