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/base/physical_location.c b/drivers/base/physical_location.c
new file mode 100644
index 000000000..2e723fff6
--- /dev/null
+++ b/drivers/base/physical_location.c
@@ -0,0 +1,144 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Device physical location support
+ *
+ * Author: Won Chung <wonchung@google.com>
+ */
+
+#include <linux/acpi.h>
+#include <linux/sysfs.h>
+#include <linux/string_choices.h>
+
+#include "physical_location.h"
+
+bool dev_add_physical_location(struct device *dev)
+{
+	struct acpi_pld_info *pld;
+
+	if (!has_acpi_companion(dev))
+		return false;
+
+	if (!acpi_get_physical_device_location(ACPI_HANDLE(dev), &pld))
+		return false;
+
+	dev->physical_location = kzalloc_obj(*dev->physical_location);
+	if (!dev->physical_location) {
+		ACPI_FREE(pld);
+		return false;
+	}
+
+	dev->physical_location->panel = pld->panel;
+	dev->physical_location->vertical_position = pld->vertical_position;
+	dev->physical_location->horizontal_position = pld->horizontal_position;
+	dev->physical_location->dock = pld->dock;
+	dev->physical_location->lid = pld->lid;
+
+	ACPI_FREE(pld);
+	return true;
+}
+
+static ssize_t panel_show(struct device *dev, struct device_attribute *attr,
+	char *buf)
+{
+	const char *panel;
+
+	switch (dev->physical_location->panel) {
+	case DEVICE_PANEL_TOP:
+		panel = "top";
+		break;
+	case DEVICE_PANEL_BOTTOM:
+		panel = "bottom";
+		break;
+	case DEVICE_PANEL_LEFT:
+		panel = "left";
+		break;
+	case DEVICE_PANEL_RIGHT:
+		panel = "right";
+		break;
+	case DEVICE_PANEL_FRONT:
+		panel = "front";
+		break;
+	case DEVICE_PANEL_BACK:
+		panel = "back";
+		break;
+	default:
+		panel = "unknown";
+	}
+	return sysfs_emit(buf, "%s\n", panel);
+}
+static DEVICE_ATTR_RO(panel);
+
+static ssize_t vertical_position_show(struct device *dev,
+	struct device_attribute *attr, char *buf)
+{
+	const char *vertical_position;
+
+	switch (dev->physical_location->vertical_position) {
+	case DEVICE_VERT_POS_UPPER:
+		vertical_position = "upper";
+		break;
+	case DEVICE_VERT_POS_CENTER:
+		vertical_position = "center";
+		break;
+	case DEVICE_VERT_POS_LOWER:
+		vertical_position = "lower";
+		break;
+	default:
+		vertical_position = "unknown";
+	}
+	return sysfs_emit(buf, "%s\n", vertical_position);
+}
+static DEVICE_ATTR_RO(vertical_position);
+
+static ssize_t horizontal_position_show(struct device *dev,
+	struct device_attribute *attr, char *buf)
+{
+	const char *horizontal_position;
+
+	switch (dev->physical_location->horizontal_position) {
+	case DEVICE_HORI_POS_LEFT:
+		horizontal_position = "left";
+		break;
+	case DEVICE_HORI_POS_CENTER:
+		horizontal_position = "center";
+		break;
+	case DEVICE_HORI_POS_RIGHT:
+		horizontal_position = "right";
+		break;
+	default:
+		horizontal_position = "unknown";
+	}
+	return sysfs_emit(buf, "%s\n", horizontal_position);
+}
+static DEVICE_ATTR_RO(horizontal_position);
+
+static ssize_t dock_show(struct device *dev, struct device_attribute *attr,
+	char *buf)
+{
+	return sysfs_emit(buf, "%s\n",
+		str_yes_no(dev->physical_location->dock));
+}
+static DEVICE_ATTR_RO(dock);
+
+static ssize_t lid_show(struct device *dev, struct device_attribute *attr,
+	char *buf)
+{
+	return sysfs_emit(buf, "%s\n",
+		str_yes_no(dev->physical_location->lid));
+}
+static DEVICE_ATTR_RO(lid);
+
+static struct attribute *dev_attr_physical_location[] = {
+	&dev_attr_panel.attr,
+	&dev_attr_vertical_position.attr,
+	&dev_attr_horizontal_position.attr,
+	&dev_attr_dock.attr,
+	&dev_attr_lid.attr,
+	NULL,
+};
+
+const struct attribute_group dev_attr_physical_location_group = {
+	.name = "physical_location",
+	.attrs = dev_attr_physical_location,
+};
+