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, 148 insertions, 0 deletions

diff --git a/drivers/cpufreq/airoha-cpufreq.c b/drivers/cpufreq/airoha-cpufreq.c
new file mode 100644
index 000000000..3e7770860
--- /dev/null
+++ b/drivers/cpufreq/airoha-cpufreq.c
@@ -0,0 +1,148 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/bitfield.h>
+#include <linux/cpufreq.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/pm_domain.h>
+#include <linux/pm_runtime.h>
+#include <linux/slab.h>
+
+#include "cpufreq-dt.h"
+
+struct airoha_cpufreq_priv {
+	int opp_token;
+	struct dev_pm_domain_list *pd_list;
+	struct platform_device *cpufreq_dt;
+};
+
+static struct platform_device *cpufreq_pdev;
+
+/* NOP function to disable OPP from setting clock */
+static int airoha_cpufreq_config_clks_nop(struct device *dev,
+					  struct opp_table *opp_table,
+					  struct dev_pm_opp *opp,
+					  void *data, bool scaling_down)
+{
+	return 0;
+}
+
+static const char * const airoha_cpufreq_clk_names[] = { "cpu", NULL };
+static const char * const airoha_cpufreq_pd_names[] = { "perf" };
+
+static int airoha_cpufreq_probe(struct platform_device *pdev)
+{
+	const struct dev_pm_domain_attach_data attach_data = {
+		.pd_names = airoha_cpufreq_pd_names,
+		.num_pd_names = ARRAY_SIZE(airoha_cpufreq_pd_names),
+		.pd_flags = PD_FLAG_DEV_LINK_ON | PD_FLAG_REQUIRED_OPP,
+	};
+	struct dev_pm_opp_config config = {
+		.clk_names = airoha_cpufreq_clk_names,
+		.config_clks = airoha_cpufreq_config_clks_nop,
+	};
+	struct platform_device *cpufreq_dt;
+	struct airoha_cpufreq_priv *priv;
+	struct device *dev = &pdev->dev;
+	struct device *cpu_dev;
+	int ret;
+
+	/* CPUs refer to the same OPP table */
+	cpu_dev = get_cpu_device(0);
+	if (!cpu_dev)
+		return -ENODEV;
+
+	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	/* Set OPP table conf with NOP config_clks */
+	priv->opp_token = dev_pm_opp_set_config(cpu_dev, &config);
+	if (priv->opp_token < 0)
+		return dev_err_probe(dev, priv->opp_token, "Failed to set OPP config\n");
+
+	/* Attach PM for OPP */
+	ret = dev_pm_domain_attach_list(cpu_dev, &attach_data,
+					&priv->pd_list);
+	if (ret)
+		goto clear_opp_config;
+
+	cpufreq_dt = platform_device_register_simple("cpufreq-dt", -1, NULL, 0);
+	ret = PTR_ERR_OR_ZERO(cpufreq_dt);
+	if (ret) {
+		dev_err(dev, "failed to create cpufreq-dt device: %d\n", ret);
+		goto detach_pm;
+	}
+
+	priv->cpufreq_dt = cpufreq_dt;
+	platform_set_drvdata(pdev, priv);
+
+	return 0;
+
+detach_pm:
+	dev_pm_domain_detach_list(priv->pd_list);
+clear_opp_config:
+	dev_pm_opp_clear_config(priv->opp_token);
+
+	return ret;
+}
+
+static void airoha_cpufreq_remove(struct platform_device *pdev)
+{
+	struct airoha_cpufreq_priv *priv = platform_get_drvdata(pdev);
+
+	platform_device_unregister(priv->cpufreq_dt);
+
+	dev_pm_domain_detach_list(priv->pd_list);
+
+	dev_pm_opp_clear_config(priv->opp_token);
+}
+
+static struct platform_driver airoha_cpufreq_driver = {
+	.probe = airoha_cpufreq_probe,
+	.remove = airoha_cpufreq_remove,
+	.driver = {
+		.name = "airoha-cpufreq",
+	},
+};
+
+static const struct of_device_id airoha_cpufreq_match_list[] __initconst = {
+	{ .compatible = "airoha,an7583" },
+	{ .compatible = "airoha,en7581" },
+	{},
+};
+MODULE_DEVICE_TABLE(of, airoha_cpufreq_match_list);
+
+static int __init airoha_cpufreq_init(void)
+{
+	const struct of_device_id *match;
+	int ret;
+
+	match = of_machine_get_match(airoha_cpufreq_match_list);
+	if (!match)
+		return -ENODEV;
+
+	ret = platform_driver_register(&airoha_cpufreq_driver);
+	if (unlikely(ret < 0))
+		return ret;
+
+	cpufreq_pdev = platform_device_register_data(NULL, "airoha-cpufreq",
+						     -1, match, sizeof(*match));
+	ret = PTR_ERR_OR_ZERO(cpufreq_pdev);
+	if (ret)
+		platform_driver_unregister(&airoha_cpufreq_driver);
+
+	return ret;
+}
+module_init(airoha_cpufreq_init);
+
+static void __exit airoha_cpufreq_exit(void)
+{
+	platform_device_unregister(cpufreq_pdev);
+	platform_driver_unregister(&airoha_cpufreq_driver);
+}
+module_exit(airoha_cpufreq_exit);
+
+MODULE_AUTHOR("Christian Marangi <ansuelsmth@gmail.com>");
+MODULE_DESCRIPTION("CPUfreq driver for Airoha SoCs");
+MODULE_LICENSE("GPL");