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, 131 insertions, 0 deletions

diff --git a/drivers/reset/reset-k210.c b/drivers/reset/reset-k210.c
new file mode 100644
index 000000000..e77e4cca3
--- /dev/null
+++ b/drivers/reset/reset-k210.c
@@ -0,0 +1,131 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) 2020 Western Digital Corporation or its affiliates.
+ */
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/reset-controller.h>
+#include <linux/delay.h>
+#include <linux/mfd/syscon.h>
+#include <linux/regmap.h>
+#include <soc/canaan/k210-sysctl.h>
+
+#include <dt-bindings/reset/k210-rst.h>
+
+#define K210_RST_MASK	0x27FFFFFF
+
+struct k210_rst {
+	struct regmap *map;
+	struct reset_controller_dev rcdev;
+};
+
+static inline struct k210_rst *
+to_k210_rst(struct reset_controller_dev *rcdev)
+{
+	return container_of(rcdev, struct k210_rst, rcdev);
+}
+
+static inline int k210_rst_assert(struct reset_controller_dev *rcdev,
+				  unsigned long id)
+{
+	struct k210_rst *ksr = to_k210_rst(rcdev);
+
+	return regmap_update_bits(ksr->map, K210_SYSCTL_PERI_RESET, BIT(id), 1);
+}
+
+static inline int k210_rst_deassert(struct reset_controller_dev *rcdev,
+				    unsigned long id)
+{
+	struct k210_rst *ksr = to_k210_rst(rcdev);
+
+	return regmap_update_bits(ksr->map, K210_SYSCTL_PERI_RESET, BIT(id), 0);
+}
+
+static int k210_rst_reset(struct reset_controller_dev *rcdev,
+			  unsigned long id)
+{
+	int ret;
+
+	ret = k210_rst_assert(rcdev, id);
+	if (ret == 0) {
+		udelay(10);
+		ret = k210_rst_deassert(rcdev, id);
+	}
+
+	return ret;
+}
+
+static int k210_rst_status(struct reset_controller_dev *rcdev,
+			   unsigned long id)
+{
+	struct k210_rst *ksr = to_k210_rst(rcdev);
+	u32 reg, bit = BIT(id);
+	int ret;
+
+	ret = regmap_read(ksr->map, K210_SYSCTL_PERI_RESET, &reg);
+	if (ret)
+		return ret;
+
+	return reg & bit;
+}
+
+static int k210_rst_xlate(struct reset_controller_dev *rcdev,
+			  const struct of_phandle_args *reset_spec)
+{
+	unsigned long id = reset_spec->args[0];
+
+	if (!(BIT(id) & K210_RST_MASK))
+		return -EINVAL;
+
+	return id;
+}
+
+static const struct reset_control_ops k210_rst_ops = {
+	.assert		= k210_rst_assert,
+	.deassert	= k210_rst_deassert,
+	.reset		= k210_rst_reset,
+	.status		= k210_rst_status,
+};
+
+static int k210_rst_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct device_node *parent_np;
+	struct k210_rst *ksr;
+
+	dev_info(dev, "K210 reset controller\n");
+
+	ksr = devm_kzalloc(dev, sizeof(*ksr), GFP_KERNEL);
+	if (!ksr)
+		return -ENOMEM;
+
+	parent_np = of_get_parent(dev->of_node);
+	ksr->map = syscon_node_to_regmap(parent_np);
+	of_node_put(parent_np);
+	if (IS_ERR(ksr->map))
+		return PTR_ERR(ksr->map);
+
+	ksr->rcdev.owner = THIS_MODULE;
+	ksr->rcdev.dev = dev;
+	ksr->rcdev.of_node = dev->of_node;
+	ksr->rcdev.ops = &k210_rst_ops;
+	ksr->rcdev.nr_resets = fls(K210_RST_MASK);
+	ksr->rcdev.of_reset_n_cells = 1;
+	ksr->rcdev.of_xlate = k210_rst_xlate;
+
+	return devm_reset_controller_register(dev, &ksr->rcdev);
+}
+
+static const struct of_device_id k210_rst_dt_ids[] = {
+	{ .compatible = "canaan,k210-rst" },
+	{ /* sentinel */ },
+};
+
+static struct platform_driver k210_rst_driver = {
+	.probe	= k210_rst_probe,
+	.driver = {
+		.name		= "k210-rst",
+		.of_match_table	= k210_rst_dt_ids,
+	},
+};
+builtin_platform_driver(k210_rst_driver);