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, 281 insertions, 0 deletions

diff --git a/drivers/opp/debugfs.c b/drivers/opp/debugfs.c
new file mode 100644
index 000000000..61506d30d
--- /dev/null
+++ b/drivers/opp/debugfs.c
@@ -0,0 +1,281 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Generic OPP debugfs interface
+ *
+ * Copyright (C) 2015-2016 Viresh Kumar <viresh.kumar@linaro.org>
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/debugfs.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/of.h>
+#include <linux/init.h>
+#include <linux/limits.h>
+#include <linux/slab.h>
+
+#include "opp.h"
+
+static struct dentry *rootdir;
+
+static void opp_set_dev_name(const struct device *dev, char *name)
+{
+	if (dev->parent)
+		snprintf(name, NAME_MAX, "%s-%s", dev_name(dev->parent),
+			 dev_name(dev));
+	else
+		snprintf(name, NAME_MAX, "%s", dev_name(dev));
+}
+
+void opp_debug_remove_one(struct dev_pm_opp *opp)
+{
+	debugfs_remove_recursive(opp->dentry);
+}
+
+static ssize_t bw_name_read(struct file *fp, char __user *userbuf,
+			    size_t count, loff_t *ppos)
+{
+	struct icc_path *path = fp->private_data;
+	const char *name = icc_get_name(path);
+	char buf[64];
+	int i = 0;
+
+	if (name)
+		i = scnprintf(buf, sizeof(buf), "%.62s\n", name);
+
+	return simple_read_from_buffer(userbuf, count, ppos, buf, i);
+}
+
+static const struct file_operations bw_name_fops = {
+	.open = simple_open,
+	.read = bw_name_read,
+	.llseek = default_llseek,
+};
+
+static void opp_debug_create_bw(struct dev_pm_opp *opp,
+				struct opp_table *opp_table,
+				struct dentry *pdentry)
+{
+	struct dentry *d;
+	char name[] = "icc-path-XXXXXXXXXXX"; /* Integers can take 11 chars max */
+	int i;
+
+	for (i = 0; i < opp_table->path_count; i++) {
+		snprintf(name, sizeof(name), "icc-path-%d", i);
+
+		/* Create per-path directory */
+		d = debugfs_create_dir(name, pdentry);
+
+		debugfs_create_file("name", S_IRUGO, d, opp_table->paths[i],
+				    &bw_name_fops);
+		debugfs_create_u32("peak_bw", S_IRUGO, d,
+				   &opp->bandwidth[i].peak);
+		debugfs_create_u32("avg_bw", S_IRUGO, d,
+				   &opp->bandwidth[i].avg);
+	}
+}
+
+static void opp_debug_create_clks(struct dev_pm_opp *opp,
+				  struct opp_table *opp_table,
+				  struct dentry *pdentry)
+{
+	char name[] = "rate_hz_XXXXXXXXXXX"; /* Integers can take 11 chars max */
+	int i;
+
+	if (opp_table->clk_count == 1) {
+		debugfs_create_ulong("rate_hz", S_IRUGO, pdentry, &opp->rates[0]);
+		return;
+	}
+
+	for (i = 0; i < opp_table->clk_count; i++) {
+		snprintf(name, sizeof(name), "rate_hz_%d", i);
+		debugfs_create_ulong(name, S_IRUGO, pdentry, &opp->rates[i]);
+	}
+}
+
+static void opp_debug_create_supplies(struct dev_pm_opp *opp,
+				      struct opp_table *opp_table,
+				      struct dentry *pdentry)
+{
+	struct dentry *d;
+	int i;
+
+	for (i = 0; i < opp_table->regulator_count; i++) {
+		char name[] = "supply-XXXXXXXXXXX"; /* Integers can take 11 chars max */
+
+		snprintf(name, sizeof(name), "supply-%d", i);
+
+		/* Create per-opp directory */
+		d = debugfs_create_dir(name, pdentry);
+
+		debugfs_create_ulong("u_volt_target", S_IRUGO, d,
+				     &opp->supplies[i].u_volt);
+
+		debugfs_create_ulong("u_volt_min", S_IRUGO, d,
+				     &opp->supplies[i].u_volt_min);
+
+		debugfs_create_ulong("u_volt_max", S_IRUGO, d,
+				     &opp->supplies[i].u_volt_max);
+
+		debugfs_create_ulong("u_amp", S_IRUGO, d,
+				     &opp->supplies[i].u_amp);
+
+		debugfs_create_ulong("u_watt", S_IRUGO, d,
+				     &opp->supplies[i].u_watt);
+	}
+}
+
+void opp_debug_create_one(struct dev_pm_opp *opp, struct opp_table *opp_table)
+{
+	struct dentry *pdentry = opp_table->dentry;
+	struct dentry *d;
+	char name[36];	/* "opp:"(4) + u64(20) + "-" (1) + u32(10) + NULL(1) */
+
+	/*
+	 * Get directory name for OPP.
+	 *
+	 * - Normally rate is unique to each OPP, use it to get unique opp-name,
+	 *   together with performance level if available.
+	 * - For some devices rate isn't available or there are multiple, use
+	 *   index instead for them.
+	 */
+	if (likely(opp_table->clk_count == 1 && opp->rates[0])) {
+		if (opp->level == OPP_LEVEL_UNSET)
+			snprintf(name, sizeof(name), "opp:%lu", opp->rates[0]);
+		else
+			snprintf(name, sizeof(name), "opp:%lu-%u", opp->rates[0], opp->level);
+	} else {
+		snprintf(name, sizeof(name), "opp:%u", _get_opp_count(opp_table));
+	}
+
+	/* Create per-opp directory */
+	d = debugfs_create_dir(name, pdentry);
+
+	debugfs_create_bool("available", S_IRUGO, d, &opp->available);
+	debugfs_create_bool("dynamic", S_IRUGO, d, &opp->dynamic);
+	debugfs_create_bool("turbo", S_IRUGO, d, &opp->turbo);
+	debugfs_create_bool("suspend", S_IRUGO, d, &opp->suspend);
+	debugfs_create_u32("level", S_IRUGO, d, &opp->level);
+	debugfs_create_ulong("clock_latency_ns", S_IRUGO, d,
+			     &opp->clock_latency_ns);
+
+	opp->of_name = of_node_full_name(opp->np);
+	debugfs_create_str("of_name", S_IRUGO, d, (char **)&opp->of_name);
+
+	opp_debug_create_clks(opp, opp_table, d);
+	opp_debug_create_supplies(opp, opp_table, d);
+	opp_debug_create_bw(opp, opp_table, d);
+
+	opp->dentry = d;
+}
+
+static void opp_list_debug_create_dir(struct opp_device *opp_dev,
+				      struct opp_table *opp_table)
+{
+	const struct device *dev = opp_dev->dev;
+	struct dentry *d;
+
+	opp_set_dev_name(dev, opp_table->dentry_name);
+
+	/* Create device specific directory */
+	d = debugfs_create_dir(opp_table->dentry_name, rootdir);
+
+	opp_dev->dentry = d;
+	opp_table->dentry = d;
+}
+
+static void opp_list_debug_create_link(struct opp_device *opp_dev,
+				       struct opp_table *opp_table)
+{
+	char name[NAME_MAX];
+
+	opp_set_dev_name(opp_dev->dev, name);
+
+	/* Create device specific directory link */
+	opp_dev->dentry = debugfs_create_symlink(name, rootdir,
+						 opp_table->dentry_name);
+}
+
+/**
+ * opp_debug_register - add a device opp node to the debugfs 'opp' directory
+ * @opp_dev: opp-dev pointer for device
+ * @opp_table: the device-opp being added
+ *
+ * Dynamically adds device specific directory in debugfs 'opp' directory. If the
+ * device-opp is shared with other devices, then links will be created for all
+ * devices except the first.
+ */
+void opp_debug_register(struct opp_device *opp_dev, struct opp_table *opp_table)
+{
+	if (opp_table->dentry)
+		opp_list_debug_create_link(opp_dev, opp_table);
+	else
+		opp_list_debug_create_dir(opp_dev, opp_table);
+}
+
+static void opp_migrate_dentry(struct opp_device *opp_dev,
+			       struct opp_table *opp_table)
+{
+	struct opp_device *new_dev = NULL, *iter;
+	const struct device *dev;
+	int err;
+
+	/* Look for next opp-dev */
+	list_for_each_entry(iter, &opp_table->dev_list, node)
+		if (iter != opp_dev) {
+			new_dev = iter;
+			break;
+		}
+
+	BUG_ON(!new_dev);
+
+	/* new_dev is guaranteed to be valid here */
+	dev = new_dev->dev;
+	debugfs_remove_recursive(new_dev->dentry);
+
+	opp_set_dev_name(dev, opp_table->dentry_name);
+
+	err = debugfs_change_name(opp_dev->dentry, "%s", opp_table->dentry_name);
+	if (err) {
+		dev_err(dev, "%s: Failed to rename link from: %s to %s\n",
+			__func__, dev_name(opp_dev->dev), dev_name(dev));
+		return;
+	}
+
+	new_dev->dentry = opp_table->dentry = opp_dev->dentry;
+}
+
+/**
+ * opp_debug_unregister - remove a device opp node from debugfs opp directory
+ * @opp_dev: opp-dev pointer for device
+ * @opp_table: the device-opp being removed
+ *
+ * Dynamically removes device specific directory from debugfs 'opp' directory.
+ */
+void opp_debug_unregister(struct opp_device *opp_dev,
+			  struct opp_table *opp_table)
+{
+	if (opp_dev->dentry == opp_table->dentry) {
+		/* Move the real dentry object under another device */
+		if (!list_is_singular(&opp_table->dev_list)) {
+			opp_migrate_dentry(opp_dev, opp_table);
+			goto out;
+		}
+		opp_table->dentry = NULL;
+	}
+
+	debugfs_remove_recursive(opp_dev->dentry);
+
+out:
+	opp_dev->dentry = NULL;
+}
+
+static int __init opp_debug_init(void)
+{
+	/* Create /sys/kernel/debug/opp directory */
+	rootdir = debugfs_create_dir("opp", NULL);
+
+	return 0;
+}
+core_initcall(opp_debug_init);