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, 111 insertions, 0 deletions

diff --git a/drivers/reset/reset-berlin.c b/drivers/reset/reset-berlin.c
new file mode 100644
index 000000000..578fe8670
--- /dev/null
+++ b/drivers/reset/reset-berlin.c
@@ -0,0 +1,111 @@
+/*
+ * Copyright (C) 2014 Marvell Technology Group Ltd.
+ *
+ * Marvell Berlin reset driver
+ *
+ * Antoine Tenart <antoine.tenart@free-electrons.com>
+ * Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
+ *
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2. This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ */
+
+#include <linux/delay.h>
+#include <linux/io.h>
+#include <linux/mfd/syscon.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/reset-controller.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+
+#define BERLIN_MAX_RESETS	32
+
+#define to_berlin_reset_priv(p)		\
+	container_of((p), struct berlin_reset_priv, rcdev)
+
+struct berlin_reset_priv {
+	struct regmap			*regmap;
+	struct reset_controller_dev	rcdev;
+};
+
+static int berlin_reset_reset(struct reset_controller_dev *rcdev,
+			      unsigned long id)
+{
+	struct berlin_reset_priv *priv = to_berlin_reset_priv(rcdev);
+	int offset = id >> 8;
+	int mask = BIT(id & 0x1f);
+
+	regmap_write(priv->regmap, offset, mask);
+
+	/* let the reset be effective */
+	udelay(10);
+
+	return 0;
+}
+
+static const struct reset_control_ops berlin_reset_ops = {
+	.reset	= berlin_reset_reset,
+};
+
+static int berlin_reset_xlate(struct reset_controller_dev *rcdev,
+			      const struct of_phandle_args *reset_spec)
+{
+	unsigned int offset, bit;
+
+	offset = reset_spec->args[0];
+	bit = reset_spec->args[1];
+
+	if (bit >= BERLIN_MAX_RESETS)
+		return -EINVAL;
+
+	return (offset << 8) | bit;
+}
+
+static int berlin2_reset_probe(struct platform_device *pdev)
+{
+	struct device_node *parent_np;
+	struct berlin_reset_priv *priv;
+
+	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	parent_np = of_get_parent(pdev->dev.of_node);
+	priv->regmap = syscon_node_to_regmap(parent_np);
+	of_node_put(parent_np);
+	if (IS_ERR(priv->regmap))
+		return PTR_ERR(priv->regmap);
+
+	priv->rcdev.owner = THIS_MODULE;
+	priv->rcdev.ops = &berlin_reset_ops;
+	priv->rcdev.of_node = pdev->dev.of_node;
+	priv->rcdev.of_reset_n_cells = 2;
+	priv->rcdev.of_xlate = berlin_reset_xlate;
+
+	return reset_controller_register(&priv->rcdev);
+}
+
+static const struct of_device_id berlin_reset_dt_match[] = {
+	{ .compatible = "marvell,berlin2-reset" },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, berlin_reset_dt_match);
+
+static struct platform_driver berlin_reset_driver = {
+	.probe	= berlin2_reset_probe,
+	.driver	= {
+		.name = "berlin2-reset",
+		.of_match_table = berlin_reset_dt_match,
+	},
+};
+module_platform_driver(berlin_reset_driver);
+
+MODULE_AUTHOR("Antoine Tenart <antoine.tenart@free-electrons.com>");
+MODULE_AUTHOR("Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>");
+MODULE_DESCRIPTION("Synaptics Berlin reset controller");
+MODULE_LICENSE("GPL");