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, 164 insertions, 0 deletions

diff --git a/drivers/mfd/sun6i-prcm.c b/drivers/mfd/sun6i-prcm.c
new file mode 100644
index 000000000..ee03db0b8
--- /dev/null
+++ b/drivers/mfd/sun6i-prcm.c
@@ -0,0 +1,164 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2014 Free Electrons
+ *
+ * Author: Boris BREZILLON <boris.brezillon@free-electrons.com>
+ *
+ * Allwinner PRCM (Power/Reset/Clock Management) driver
+ */
+
+#include <linux/mfd/core.h>
+#include <linux/init.h>
+#include <linux/of.h>
+
+#define SUN8I_CODEC_ANALOG_BASE	0x1c0
+#define SUN8I_CODEC_ANALOG_SIZE	0x4
+
+struct prcm_data {
+	int nsubdevs;
+	const struct mfd_cell *subdevs;
+};
+
+static const struct resource sun6i_a31_ar100_clk_res[] = {
+	DEFINE_RES_MEM(0x0, 4)
+};
+
+static const struct resource sun6i_a31_apb0_clk_res[] = {
+	DEFINE_RES_MEM(0xc, 4)
+};
+
+static const struct resource sun6i_a31_apb0_gates_clk_res[] = {
+	DEFINE_RES_MEM(0x28, 4)
+};
+
+static const struct resource sun6i_a31_ir_clk_res[] = {
+	DEFINE_RES_MEM(0x54, 4)
+};
+
+static const struct resource sun6i_a31_apb0_rstc_res[] = {
+	DEFINE_RES_MEM(0xb0, 4)
+};
+
+static const struct resource sun8i_codec_analog_res[] = {
+	DEFINE_RES_MEM(SUN8I_CODEC_ANALOG_BASE, SUN8I_CODEC_ANALOG_SIZE),
+};
+
+static const struct mfd_cell sun6i_a31_prcm_subdevs[] = {
+	{
+		.name = "sun6i-a31-ar100-clk",
+		.of_compatible = "allwinner,sun6i-a31-ar100-clk",
+		.num_resources = ARRAY_SIZE(sun6i_a31_ar100_clk_res),
+		.resources = sun6i_a31_ar100_clk_res,
+	},
+	{
+		.name = "sun6i-a31-apb0-clk",
+		.of_compatible = "allwinner,sun6i-a31-apb0-clk",
+		.num_resources = ARRAY_SIZE(sun6i_a31_apb0_clk_res),
+		.resources = sun6i_a31_apb0_clk_res,
+	},
+	{
+		.name = "sun6i-a31-apb0-gates-clk",
+		.of_compatible = "allwinner,sun6i-a31-apb0-gates-clk",
+		.num_resources = ARRAY_SIZE(sun6i_a31_apb0_gates_clk_res),
+		.resources = sun6i_a31_apb0_gates_clk_res,
+	},
+	{
+		.name = "sun6i-a31-ir-clk",
+		.of_compatible = "allwinner,sun4i-a10-mod0-clk",
+		.num_resources = ARRAY_SIZE(sun6i_a31_ir_clk_res),
+		.resources = sun6i_a31_ir_clk_res,
+	},
+	{
+		.name = "sun6i-a31-apb0-clock-reset",
+		.of_compatible = "allwinner,sun6i-a31-clock-reset",
+		.num_resources = ARRAY_SIZE(sun6i_a31_apb0_rstc_res),
+		.resources = sun6i_a31_apb0_rstc_res,
+	},
+};
+
+static const struct mfd_cell sun8i_a23_prcm_subdevs[] = {
+	{
+		.name = "sun8i-a23-apb0-clk",
+		.of_compatible = "allwinner,sun8i-a23-apb0-clk",
+		.num_resources = ARRAY_SIZE(sun6i_a31_apb0_clk_res),
+		.resources = sun6i_a31_apb0_clk_res,
+	},
+	{
+		.name = "sun6i-a31-apb0-gates-clk",
+		.of_compatible = "allwinner,sun8i-a23-apb0-gates-clk",
+		.num_resources = ARRAY_SIZE(sun6i_a31_apb0_gates_clk_res),
+		.resources = sun6i_a31_apb0_gates_clk_res,
+	},
+	{
+		.name = "sun6i-a31-apb0-clock-reset",
+		.of_compatible = "allwinner,sun6i-a31-clock-reset",
+		.num_resources = ARRAY_SIZE(sun6i_a31_apb0_rstc_res),
+		.resources = sun6i_a31_apb0_rstc_res,
+	},
+	{
+		.name		= "sun8i-codec-analog",
+		.of_compatible	= "allwinner,sun8i-a23-codec-analog",
+		.num_resources	= ARRAY_SIZE(sun8i_codec_analog_res),
+		.resources	= sun8i_codec_analog_res,
+	},
+};
+
+static const struct prcm_data sun6i_a31_prcm_data = {
+	.nsubdevs = ARRAY_SIZE(sun6i_a31_prcm_subdevs),
+	.subdevs = sun6i_a31_prcm_subdevs,
+};
+
+static const struct prcm_data sun8i_a23_prcm_data = {
+	.nsubdevs = ARRAY_SIZE(sun8i_a23_prcm_subdevs),
+	.subdevs = sun8i_a23_prcm_subdevs,
+};
+
+static const struct of_device_id sun6i_prcm_dt_ids[] = {
+	{
+		.compatible = "allwinner,sun6i-a31-prcm",
+		.data = &sun6i_a31_prcm_data,
+	},
+	{
+		.compatible = "allwinner,sun8i-a23-prcm",
+		.data = &sun8i_a23_prcm_data,
+	},
+	{ /* sentinel */ },
+};
+
+static int sun6i_prcm_probe(struct platform_device *pdev)
+{
+	const struct of_device_id *match;
+	const struct prcm_data *data;
+	struct resource *res;
+	int ret;
+
+	match = of_match_node(sun6i_prcm_dt_ids, pdev->dev.of_node);
+	if (!match)
+		return -EINVAL;
+
+	data = match->data;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res) {
+		dev_err(&pdev->dev, "no prcm memory region provided\n");
+		return -ENOENT;
+	}
+
+	ret = mfd_add_devices(&pdev->dev, 0, data->subdevs, data->nsubdevs,
+			      res, -1, NULL);
+	if (ret) {
+		dev_err(&pdev->dev, "failed to add subdevices\n");
+		return ret;
+	}
+
+	return 0;
+}
+
+static struct platform_driver sun6i_prcm_driver = {
+	.driver = {
+		.name = "sun6i-prcm",
+		.of_match_table = sun6i_prcm_dt_ids,
+	},
+	.probe = sun6i_prcm_probe,
+};
+builtin_platform_driver(sun6i_prcm_driver);