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, 113 insertions, 0 deletions

diff --git a/drivers/cpufreq/tegra20-cpufreq.c b/drivers/cpufreq/tegra20-cpufreq.c
new file mode 100644
index 000000000..a57318670
--- /dev/null
+++ b/drivers/cpufreq/tegra20-cpufreq.c
@@ -0,0 +1,113 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2010 Google, Inc.
+ *
+ * Author:
+ *	Colin Cross <ccross@google.com>
+ *	Based on arch/arm/plat-omap/cpu-omap.c, (C) 2005 Nokia Corporation
+ */
+
+#include <linux/bits.h>
+#include <linux/cpu.h>
+#include <linux/err.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/pm_opp.h>
+#include <linux/types.h>
+
+#include <soc/tegra/common.h>
+#include <soc/tegra/fuse.h>
+
+static bool cpu0_node_has_opp_v2_prop(void)
+{
+	struct device_node *np = of_cpu_device_node_get(0);
+	bool ret = false;
+
+	if (of_property_present(np, "operating-points-v2"))
+		ret = true;
+
+	of_node_put(np);
+	return ret;
+}
+
+static void tegra20_cpufreq_put_supported_hw(void *opp_token)
+{
+	dev_pm_opp_put_supported_hw((unsigned long) opp_token);
+}
+
+static void tegra20_cpufreq_dt_unregister(void *cpufreq_dt)
+{
+	platform_device_unregister(cpufreq_dt);
+}
+
+static int tegra20_cpufreq_probe(struct platform_device *pdev)
+{
+	struct platform_device *cpufreq_dt;
+	struct device *cpu_dev;
+	u32 versions[2];
+	int err;
+
+	if (!cpu0_node_has_opp_v2_prop()) {
+		dev_err(&pdev->dev, "operating points not found\n");
+		dev_err(&pdev->dev, "please update your device tree\n");
+		return -ENODEV;
+	}
+
+	if (of_machine_is_compatible("nvidia,tegra20")) {
+		versions[0] = BIT(tegra_sku_info.cpu_process_id);
+		versions[1] = BIT(tegra_sku_info.soc_speedo_id);
+	} else {
+		versions[0] = BIT(tegra_sku_info.cpu_process_id);
+		versions[1] = BIT(tegra_sku_info.cpu_speedo_id);
+	}
+
+	dev_info(&pdev->dev, "hardware version 0x%x 0x%x\n",
+		 versions[0], versions[1]);
+
+	cpu_dev = get_cpu_device(0);
+	if (WARN_ON(!cpu_dev))
+		return -ENODEV;
+
+	err = dev_pm_opp_set_supported_hw(cpu_dev, versions, 2);
+	if (err < 0) {
+		dev_err(&pdev->dev, "failed to set supported hw: %d\n", err);
+		return err;
+	}
+
+	err = devm_add_action_or_reset(&pdev->dev,
+				       tegra20_cpufreq_put_supported_hw,
+				       (void *)((unsigned long) err));
+	if (err)
+		return err;
+
+	cpufreq_dt = platform_device_register_simple("cpufreq-dt", -1, NULL, 0);
+	err = PTR_ERR_OR_ZERO(cpufreq_dt);
+	if (err) {
+		dev_err(&pdev->dev,
+			"failed to create cpufreq-dt device: %d\n", err);
+		return err;
+	}
+
+	err = devm_add_action_or_reset(&pdev->dev,
+				       tegra20_cpufreq_dt_unregister,
+				       cpufreq_dt);
+	if (err)
+		return err;
+
+	return 0;
+}
+
+static struct platform_driver tegra20_cpufreq_driver = {
+	.probe		= tegra20_cpufreq_probe,
+	.driver		= {
+		.name	= "tegra20-cpufreq",
+	},
+};
+module_platform_driver(tegra20_cpufreq_driver);
+
+MODULE_ALIAS("platform:tegra20-cpufreq");
+MODULE_AUTHOR("Colin Cross <ccross@android.com>");
+MODULE_DESCRIPTION("NVIDIA Tegra20 cpufreq driver");
+MODULE_LICENSE("GPL");