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, 81 insertions, 0 deletions

diff --git a/drivers/reset/reset-axs10x.c b/drivers/reset/reset-axs10x.c
new file mode 100644
index 000000000..ea0e6b0b6
--- /dev/null
+++ b/drivers/reset/reset-axs10x.c
@@ -0,0 +1,81 @@
+/*
+ * Copyright (C) 2017 Synopsys.
+ *
+ * Synopsys AXS10x reset driver.
+ *
+ * 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/io.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/reset-controller.h>
+
+#define to_axs10x_rst(p)	container_of((p), struct axs10x_rst, rcdev)
+
+#define AXS10X_MAX_RESETS	32
+
+struct axs10x_rst {
+	void __iomem			*regs_rst;
+	spinlock_t			lock;
+	struct reset_controller_dev	rcdev;
+};
+
+static int axs10x_reset_reset(struct reset_controller_dev *rcdev,
+			      unsigned long id)
+{
+	struct axs10x_rst *rst = to_axs10x_rst(rcdev);
+	unsigned long flags;
+
+	spin_lock_irqsave(&rst->lock, flags);
+	writel(BIT(id), rst->regs_rst);
+	spin_unlock_irqrestore(&rst->lock, flags);
+
+	return 0;
+}
+
+static const struct reset_control_ops axs10x_reset_ops = {
+	.reset	= axs10x_reset_reset,
+};
+
+static int axs10x_reset_probe(struct platform_device *pdev)
+{
+	struct axs10x_rst *rst;
+
+	rst = devm_kzalloc(&pdev->dev, sizeof(*rst), GFP_KERNEL);
+	if (!rst)
+		return -ENOMEM;
+
+	rst->regs_rst = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(rst->regs_rst))
+		return PTR_ERR(rst->regs_rst);
+
+	spin_lock_init(&rst->lock);
+
+	rst->rcdev.owner = THIS_MODULE;
+	rst->rcdev.ops = &axs10x_reset_ops;
+	rst->rcdev.of_node = pdev->dev.of_node;
+	rst->rcdev.nr_resets = AXS10X_MAX_RESETS;
+
+	return devm_reset_controller_register(&pdev->dev, &rst->rcdev);
+}
+
+static const struct of_device_id axs10x_reset_dt_match[] = {
+	{ .compatible = "snps,axs10x-reset" },
+	{ },
+};
+
+static struct platform_driver axs10x_reset_driver = {
+	.probe	= axs10x_reset_probe,
+	.driver	= {
+		.name = "axs10x-reset",
+		.of_match_table = axs10x_reset_dt_match,
+	},
+};
+builtin_platform_driver(axs10x_reset_driver);
+
+MODULE_AUTHOR("Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>");
+MODULE_DESCRIPTION("Synopsys AXS10x reset driver");
+MODULE_LICENSE("GPL v2");