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, 101 insertions, 0 deletions

diff --git a/drivers/reset/reset-imx-scu.c b/drivers/reset/reset-imx-scu.c
new file mode 100644
index 000000000..919fc29f9
--- /dev/null
+++ b/drivers/reset/reset-imx-scu.c
@@ -0,0 +1,101 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright 2025 NXP
+ * Frank Li <Frank.Li@nxp.com>
+ */
+#include <linux/firmware/imx/svc/misc.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/reset-controller.h>
+
+#include <dt-bindings/firmware/imx/rsrc.h>
+
+struct imx_scu_reset {
+	struct reset_controller_dev rc;
+	struct imx_sc_ipc *ipc_handle;
+};
+
+static struct imx_scu_reset *to_imx_scu(struct reset_controller_dev *rc)
+{
+	return container_of(rc, struct imx_scu_reset, rc);
+}
+
+struct imx_scu_id_map {
+	u32 resource_id;
+	u32 command_id;
+};
+
+static const struct imx_scu_id_map imx_scu_id_map[] = {
+	{ IMX_SC_R_CSI_0, IMX_SC_C_MIPI_RESET },
+	{ IMX_SC_R_CSI_1, IMX_SC_C_MIPI_RESET },
+};
+
+static int imx_scu_reset_assert(struct reset_controller_dev *rc, unsigned long id)
+{
+	struct imx_scu_reset *priv = to_imx_scu(rc);
+
+	return imx_sc_misc_set_control(priv->ipc_handle, imx_scu_id_map[id].resource_id,
+				       imx_scu_id_map[id].command_id, true);
+}
+
+static const struct reset_control_ops imx_scu_reset_ops = {
+	.assert = imx_scu_reset_assert,
+};
+
+static int imx_scu_xlate(struct reset_controller_dev *rc, const struct of_phandle_args *reset_spec)
+{
+	int i;
+
+	for (i = 0; i < rc->nr_resets; i++)
+		if (reset_spec->args[0] == imx_scu_id_map[i].resource_id)
+			return i;
+
+	return -EINVAL;
+}
+
+static int imx_scu_reset_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct imx_scu_reset *priv;
+	int ret;
+
+	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	platform_set_drvdata(pdev, &priv->rc);
+
+	ret = imx_scu_get_handle(&priv->ipc_handle);
+	if (ret)
+		return dev_err_probe(dev, ret, "sc_misc_MIPI get ipc handle failed!\n");
+
+	priv->rc.ops = &imx_scu_reset_ops;
+	priv->rc.owner = THIS_MODULE;
+	priv->rc.of_node = dev->of_node;
+	priv->rc.of_reset_n_cells = 1;
+	priv->rc.of_xlate = imx_scu_xlate;
+	priv->rc.nr_resets = ARRAY_SIZE(imx_scu_id_map);
+
+	return devm_reset_controller_register(dev, &priv->rc);
+}
+
+static const struct of_device_id imx_scu_reset_ids[] = {
+	{ .compatible = "fsl,imx-scu-reset", },
+	{}
+};
+MODULE_DEVICE_TABLE(of, imx_scu_reset_ids);
+
+static struct platform_driver imx_scu_reset_driver = {
+	.probe          = imx_scu_reset_probe,
+	.driver = {
+		.name = "scu-reset",
+		.of_match_table = imx_scu_reset_ids,
+	},
+};
+module_platform_driver(imx_scu_reset_driver);
+
+MODULE_AUTHOR("Frank Li <Frank.Li@nxp.com>");
+MODULE_DESCRIPTION("i.MX scu reset driver");
+MODULE_LICENSE("GPL");