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, 106 insertions, 0 deletions

diff --git a/drivers/clk/qcom/clk-regmap.c b/drivers/clk/qcom/clk-regmap.c
new file mode 100644
index 000000000..92ac4e0d7
--- /dev/null
+++ b/drivers/clk/qcom/clk-regmap.c
@@ -0,0 +1,106 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2014, The Linux Foundation. All rights reserved.
+ */
+
+#include <linux/device.h>
+#include <linux/clk-provider.h>
+#include <linux/regmap.h>
+#include <linux/export.h>
+
+#include "clk-regmap.h"
+
+/**
+ * clk_is_enabled_regmap - standard is_enabled() for regmap users
+ *
+ * @hw: clk to operate on
+ *
+ * Clocks that use regmap for their register I/O can set the
+ * enable_reg and enable_mask fields in their struct clk_regmap and then use
+ * this as their is_enabled operation, saving some code.
+ */
+int clk_is_enabled_regmap(struct clk_hw *hw)
+{
+	struct clk_regmap *rclk = to_clk_regmap(hw);
+	unsigned int val;
+	int ret;
+
+	ret = regmap_read(rclk->regmap, rclk->enable_reg, &val);
+	if (ret != 0)
+		return ret;
+
+	if (rclk->enable_is_inverted)
+		return (val & rclk->enable_mask) == 0;
+	else
+		return (val & rclk->enable_mask) != 0;
+}
+EXPORT_SYMBOL_GPL(clk_is_enabled_regmap);
+
+/**
+ * clk_enable_regmap - standard enable() for regmap users
+ *
+ * @hw: clk to operate on
+ *
+ * Clocks that use regmap for their register I/O can set the
+ * enable_reg and enable_mask fields in their struct clk_regmap and then use
+ * this as their enable() operation, saving some code.
+ */
+int clk_enable_regmap(struct clk_hw *hw)
+{
+	struct clk_regmap *rclk = to_clk_regmap(hw);
+	unsigned int val;
+
+	if (rclk->enable_is_inverted)
+		val = 0;
+	else
+		val = rclk->enable_mask;
+
+	return regmap_update_bits(rclk->regmap, rclk->enable_reg,
+				  rclk->enable_mask, val);
+}
+EXPORT_SYMBOL_GPL(clk_enable_regmap);
+
+/**
+ * clk_disable_regmap - standard disable() for regmap users
+ *
+ * @hw: clk to operate on
+ *
+ * Clocks that use regmap for their register I/O can set the
+ * enable_reg and enable_mask fields in their struct clk_regmap and then use
+ * this as their disable() operation, saving some code.
+ */
+void clk_disable_regmap(struct clk_hw *hw)
+{
+	struct clk_regmap *rclk = to_clk_regmap(hw);
+	unsigned int val;
+
+	if (rclk->enable_is_inverted)
+		val = rclk->enable_mask;
+	else
+		val = 0;
+
+	regmap_update_bits(rclk->regmap, rclk->enable_reg, rclk->enable_mask,
+			   val);
+}
+EXPORT_SYMBOL_GPL(clk_disable_regmap);
+
+/**
+ * devm_clk_register_regmap - register a clk_regmap clock
+ *
+ * @dev: reference to the caller's device
+ * @rclk: clk to operate on
+ *
+ * Clocks that use regmap for their register I/O should register their
+ * clk_regmap struct via this function so that the regmap is initialized
+ * and so that the clock is registered with the common clock framework.
+ */
+int devm_clk_register_regmap(struct device *dev, struct clk_regmap *rclk)
+{
+	if (dev && dev_get_regmap(dev, NULL))
+		rclk->regmap = dev_get_regmap(dev, NULL);
+	else if (dev && dev->parent)
+		rclk->regmap = dev_get_regmap(dev->parent, NULL);
+
+	return devm_clk_hw_register(dev, &rclk->hw);
+}
+EXPORT_SYMBOL_GPL(devm_clk_register_regmap);