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, 205 insertions, 0 deletions

diff --git a/drivers/clk/qcom/clk-ref.c b/drivers/clk/qcom/clk-ref.c
new file mode 100644
index 000000000..3efdf6749
--- /dev/null
+++ b/drivers/clk/qcom/clk-ref.c
@@ -0,0 +1,205 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2026, Qualcomm Technologies, Inc. and/or its subsidiaries.
+ */
+
+#include <linux/clk-provider.h>
+#include <linux/clk/qcom.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/export.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/regulator/consumer.h>
+#include <linux/slab.h>
+
+#define QCOM_CLK_REF_EN_MASK BIT(0)
+
+struct qcom_clk_ref_provider {
+	size_t num_refs;
+	struct qcom_clk_ref refs[] __counted_by(num_refs);
+};
+
+static inline struct qcom_clk_ref *to_qcom_clk_ref(struct clk_hw *hw)
+{
+	return container_of(hw, struct qcom_clk_ref, hw);
+}
+
+static const struct clk_parent_data qcom_clk_ref_parent_data = {
+	.index = 0,
+};
+
+static int qcom_clk_ref_prepare(struct clk_hw *hw)
+{
+	struct qcom_clk_ref *rclk = to_qcom_clk_ref(hw);
+	int ret;
+
+	if (!rclk->desc.num_regulators)
+		return 0;
+
+	ret = regulator_bulk_enable(rclk->desc.num_regulators, rclk->regulators);
+	if (ret)
+		pr_err("Failed to enable regulators for %s: %d\n",
+		       clk_hw_get_name(hw), ret);
+
+	return ret;
+}
+
+static void qcom_clk_ref_unprepare(struct clk_hw *hw)
+{
+	struct qcom_clk_ref *rclk = to_qcom_clk_ref(hw);
+
+	if (rclk->desc.num_regulators)
+		regulator_bulk_disable(rclk->desc.num_regulators, rclk->regulators);
+}
+
+static int qcom_clk_ref_enable(struct clk_hw *hw)
+{
+	struct qcom_clk_ref *rclk = to_qcom_clk_ref(hw);
+	int ret;
+
+	ret = regmap_set_bits(rclk->regmap, rclk->desc.offset, QCOM_CLK_REF_EN_MASK);
+	if (ret)
+		return ret;
+
+	udelay(10);
+
+	return 0;
+}
+
+static void qcom_clk_ref_disable(struct clk_hw *hw)
+{
+	struct qcom_clk_ref *rclk = to_qcom_clk_ref(hw);
+
+	regmap_clear_bits(rclk->regmap, rclk->desc.offset, QCOM_CLK_REF_EN_MASK);
+	udelay(10);
+}
+
+static int qcom_clk_ref_is_enabled(struct clk_hw *hw)
+{
+	struct qcom_clk_ref *rclk = to_qcom_clk_ref(hw);
+	u32 val;
+	int ret;
+
+	ret = regmap_read(rclk->regmap, rclk->desc.offset, &val);
+	if (ret)
+		return 0;
+
+	return !!(val & QCOM_CLK_REF_EN_MASK);
+}
+
+static const struct clk_ops qcom_clk_ref_ops = {
+	.prepare = qcom_clk_ref_prepare,
+	.unprepare = qcom_clk_ref_unprepare,
+	.enable = qcom_clk_ref_enable,
+	.disable = qcom_clk_ref_disable,
+	.is_enabled = qcom_clk_ref_is_enabled,
+};
+
+static int qcom_clk_ref_register(struct device *dev, struct regmap *regmap,
+				 struct qcom_clk_ref *clk_refs,
+				 const struct qcom_clk_ref_desc * const *descs,
+				 size_t num_clk_refs)
+{
+	const struct qcom_clk_ref_desc *desc;
+	struct clk_init_data init_data = {};
+	struct qcom_clk_ref *clk_ref;
+	size_t clk_idx;
+	unsigned int i;
+	int ret;
+
+	for (clk_idx = 0; clk_idx < num_clk_refs; clk_idx++) {
+		clk_ref = &clk_refs[clk_idx];
+		desc = descs[clk_idx];
+
+		/* Skip unpopulated indices; the array is indexed by clock ID. */
+		if (!desc)
+			continue;
+
+		if (WARN_ON(!desc->name))
+			continue;
+
+		clk_ref->regmap = regmap;
+		clk_ref->desc = *desc;
+
+		if (clk_ref->desc.num_regulators) {
+			clk_ref->regulators = devm_kcalloc(dev, clk_ref->desc.num_regulators,
+							   sizeof(*clk_ref->regulators),
+							   GFP_KERNEL);
+			if (!clk_ref->regulators)
+				return -ENOMEM;
+
+			for (i = 0; i < clk_ref->desc.num_regulators; i++)
+				clk_ref->regulators[i].supply =
+					clk_ref->desc.regulator_names[i];
+
+			ret = devm_regulator_bulk_get(dev, clk_ref->desc.num_regulators,
+						      clk_ref->regulators);
+			if (ret)
+				return dev_err_probe(dev, ret,
+						     "Failed to get regulators for %s\n",
+						     clk_ref->desc.name);
+		}
+
+		init_data.name = clk_ref->desc.name;
+		init_data.parent_data = &qcom_clk_ref_parent_data;
+		init_data.num_parents = 1;
+		init_data.ops = &qcom_clk_ref_ops;
+		clk_ref->hw.init = &init_data;
+
+		ret = devm_clk_hw_register(dev, &clk_ref->hw);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
+static struct clk_hw *qcom_clk_ref_provider_get(struct of_phandle_args *clkspec, void *data)
+{
+	struct qcom_clk_ref_provider *provider = data;
+	unsigned int idx = clkspec->args[0];
+
+	if (idx >= provider->num_refs)
+		return ERR_PTR(-EINVAL);
+
+	if (!provider->refs[idx].regmap)
+		return ERR_PTR(-ENOENT);
+
+	return &provider->refs[idx].hw;
+}
+
+int qcom_clk_ref_probe(struct platform_device *pdev,
+		       const struct regmap_config *config,
+		       const struct qcom_clk_ref_desc * const *descs,
+		       size_t num_clk_refs)
+{
+	struct qcom_clk_ref_provider *provider;
+	struct device *dev = &pdev->dev;
+	struct regmap *regmap;
+	void __iomem *base;
+	int ret;
+
+	base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(base))
+		return PTR_ERR(base);
+
+	regmap = devm_regmap_init_mmio(dev, base, config);
+	if (IS_ERR(regmap))
+		return PTR_ERR(regmap);
+
+	provider = devm_kzalloc(dev, struct_size(provider, refs, num_clk_refs),
+				GFP_KERNEL);
+	if (!provider)
+		return -ENOMEM;
+
+	provider->num_refs = num_clk_refs;
+
+	ret = qcom_clk_ref_register(dev, regmap, provider->refs, descs,
+				    provider->num_refs);
+	if (ret)
+		return ret;
+
+	return devm_of_clk_add_hw_provider(dev, qcom_clk_ref_provider_get, provider);
+}
+EXPORT_SYMBOL_GPL(qcom_clk_ref_probe);