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/clk/sprd/common.c b/drivers/clk/sprd/common.c
new file mode 100644
index 000000000..0f2181617
--- /dev/null
+++ b/drivers/clk/sprd/common.c
@@ -0,0 +1,113 @@
+// SPDX-License-Identifier: GPL-2.0
+//
+// Spreadtrum clock infrastructure
+//
+// Copyright (C) 2017 Spreadtrum, Inc.
+// Author: Chunyan Zhang <chunyan.zhang@spreadtrum.com>
+
+#include <linux/mfd/syscon.h>
+#include <linux/module.h>
+#include <linux/of_address.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+
+#include "common.h"
+
+static const struct regmap_config sprdclk_regmap_config = {
+	.reg_bits	= 32,
+	.reg_stride	= 4,
+	.val_bits	= 32,
+	.fast_io	= true,
+};
+
+static void sprd_clk_set_regmap(const struct sprd_clk_desc *desc,
+			 struct regmap *regmap)
+{
+	int i;
+	struct sprd_clk_common *cclk;
+
+	for (i = 0; i < desc->num_clk_clks; i++) {
+		cclk = desc->clk_clks[i];
+		if (!cclk)
+			continue;
+
+		cclk->regmap = regmap;
+	}
+}
+
+int sprd_clk_regmap_init(struct platform_device *pdev,
+			 const struct sprd_clk_desc *desc)
+{
+	void __iomem *base;
+	struct device *dev = &pdev->dev;
+	struct device_node *node = dev->of_node, *np;
+	struct regmap *regmap;
+	struct resource *res;
+	struct regmap_config reg_config = sprdclk_regmap_config;
+
+	if (of_property_present(node, "sprd,syscon")) {
+		regmap = syscon_regmap_lookup_by_phandle(node, "sprd,syscon");
+		if (IS_ERR(regmap)) {
+			pr_err("%s: failed to get syscon regmap\n", __func__);
+			return PTR_ERR(regmap);
+		}
+	} else if (of_device_is_compatible(np =	of_get_parent(node), "syscon") ||
+		   (of_node_put(np), 0)) {
+		regmap = device_node_to_regmap(np);
+		of_node_put(np);
+		if (IS_ERR(regmap)) {
+			dev_err(dev, "failed to get regmap from its parent.\n");
+			return PTR_ERR(regmap);
+		}
+	} else {
+		base = devm_platform_get_and_ioremap_resource(pdev, 0, &res);
+		if (IS_ERR(base))
+			return PTR_ERR(base);
+
+		reg_config.max_register = resource_size(res) - reg_config.reg_stride;
+
+		regmap = devm_regmap_init_mmio(&pdev->dev, base,
+					       &reg_config);
+		if (IS_ERR(regmap)) {
+			pr_err("failed to init regmap\n");
+			return PTR_ERR(regmap);
+		}
+	}
+
+	sprd_clk_set_regmap(desc, regmap);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(sprd_clk_regmap_init);
+
+int sprd_clk_probe(struct device *dev, struct clk_hw_onecell_data *clkhw)
+{
+	int i, ret;
+	struct clk_hw *hw;
+
+	for (i = 0; i < clkhw->num; i++) {
+		const char *name;
+
+		hw = clkhw->hws[i];
+		if (!hw)
+			continue;
+
+		name = hw->init->name;
+		ret = devm_clk_hw_register(dev, hw);
+		if (ret) {
+			dev_err(dev, "Couldn't register clock %d - %s\n",
+				i, name);
+			return ret;
+		}
+	}
+
+	ret = devm_of_clk_add_hw_provider(dev, of_clk_hw_onecell_get, clkhw);
+	if (ret)
+		dev_err(dev, "Failed to add clock provider\n");
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(sprd_clk_probe);
+
+MODULE_DESCRIPTION("Spreadtrum clock infrastructure");
+MODULE_LICENSE("GPL v2");