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, 223 insertions, 0 deletions

diff --git a/drivers/soc/pxa/ssp.c b/drivers/soc/pxa/ssp.c
new file mode 100644
index 000000000..bb0062c16
--- /dev/null
+++ b/drivers/soc/pxa/ssp.c
@@ -0,0 +1,223 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *  linux/arch/arm/mach-pxa/ssp.c
+ *
+ *  based on linux/arch/arm/mach-sa1100/ssp.c by Russell King
+ *
+ *  Copyright (C) 2003 Russell King.
+ *  Copyright (C) 2003 Wolfson Microelectronics PLC
+ *
+ *  PXA2xx SSP driver.  This provides the generic core for simple
+ *  IO-based SSP applications and allows easy port setup for DMA access.
+ *
+ *  Author: Liam Girdwood <liam.girdwood@wolfsonmicro.com>
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/errno.h>
+#include <linux/interrupt.h>
+#include <linux/ioport.h>
+#include <linux/init.h>
+#include <linux/mutex.h>
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/platform_device.h>
+#include <linux/pxa2xx_ssp.h>
+#include <linux/io.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+
+#include <asm/irq.h>
+
+static DEFINE_MUTEX(ssp_lock);
+static LIST_HEAD(ssp_list);
+
+struct ssp_device *pxa_ssp_request(int port, const char *label)
+{
+	struct ssp_device *ssp = NULL;
+
+	mutex_lock(&ssp_lock);
+
+	list_for_each_entry(ssp, &ssp_list, node) {
+		if (ssp->port_id == port && ssp->use_count == 0) {
+			ssp->use_count++;
+			ssp->label = label;
+			break;
+		}
+	}
+
+	mutex_unlock(&ssp_lock);
+
+	if (&ssp->node == &ssp_list)
+		return NULL;
+
+	return ssp;
+}
+EXPORT_SYMBOL(pxa_ssp_request);
+
+struct ssp_device *pxa_ssp_request_of(const struct device_node *of_node,
+				      const char *label)
+{
+	struct ssp_device *ssp = NULL;
+
+	mutex_lock(&ssp_lock);
+
+	list_for_each_entry(ssp, &ssp_list, node) {
+		if (ssp->of_node == of_node && ssp->use_count == 0) {
+			ssp->use_count++;
+			ssp->label = label;
+			break;
+		}
+	}
+
+	mutex_unlock(&ssp_lock);
+
+	if (&ssp->node == &ssp_list)
+		return NULL;
+
+	return ssp;
+}
+EXPORT_SYMBOL(pxa_ssp_request_of);
+
+void pxa_ssp_free(struct ssp_device *ssp)
+{
+	mutex_lock(&ssp_lock);
+	if (ssp->use_count) {
+		ssp->use_count--;
+		ssp->label = NULL;
+	} else
+		dev_err(ssp->dev, "device already free\n");
+	mutex_unlock(&ssp_lock);
+}
+EXPORT_SYMBOL(pxa_ssp_free);
+
+#ifdef CONFIG_OF
+static const struct of_device_id pxa_ssp_of_ids[] = {
+	{ .compatible = "mrvl,pxa25x-ssp",	.data = (void *) PXA25x_SSP },
+	{ .compatible = "mvrl,pxa25x-nssp",	.data = (void *) PXA25x_NSSP },
+	{ .compatible = "mrvl,pxa27x-ssp",	.data = (void *) PXA27x_SSP },
+	{ .compatible = "mrvl,pxa3xx-ssp",	.data = (void *) PXA3xx_SSP },
+	{ .compatible = "mvrl,pxa168-ssp",	.data = (void *) PXA168_SSP },
+	{ .compatible = "mrvl,pxa910-ssp",	.data = (void *) PXA910_SSP },
+	{ .compatible = "mrvl,ce4100-ssp",	.data = (void *) CE4100_SSP },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, pxa_ssp_of_ids);
+#endif
+
+static int pxa_ssp_probe(struct platform_device *pdev)
+{
+	struct resource *res;
+	struct ssp_device *ssp;
+	struct device *dev = &pdev->dev;
+
+	ssp = devm_kzalloc(dev, sizeof(struct ssp_device), GFP_KERNEL);
+	if (ssp == NULL)
+		return -ENOMEM;
+
+	ssp->dev = dev;
+
+	ssp->clk = devm_clk_get(dev, NULL);
+	if (IS_ERR(ssp->clk))
+		return PTR_ERR(ssp->clk);
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (res == NULL) {
+		dev_err(dev, "no memory resource defined\n");
+		return -ENODEV;
+	}
+
+	res = devm_request_mem_region(dev, res->start, resource_size(res),
+				      pdev->name);
+	if (res == NULL) {
+		dev_err(dev, "failed to request memory resource\n");
+		return -EBUSY;
+	}
+
+	ssp->phys_base = res->start;
+
+	ssp->mmio_base = devm_ioremap(dev, res->start, resource_size(res));
+	if (ssp->mmio_base == NULL) {
+		dev_err(dev, "failed to ioremap() registers\n");
+		return -ENODEV;
+	}
+
+	ssp->irq = platform_get_irq(pdev, 0);
+	if (ssp->irq < 0)
+		return -ENODEV;
+
+	if (dev->of_node) {
+		const struct of_device_id *id =
+			of_match_device(of_match_ptr(pxa_ssp_of_ids), dev);
+		ssp->type = (uintptr_t) id->data;
+	} else {
+		const struct platform_device_id *id =
+			platform_get_device_id(pdev);
+		ssp->type = id->driver_data;
+
+		/* PXA2xx/3xx SSP ports starts from 1 and the internal pdev->id
+		 * starts from 0, do a translation here
+		 */
+		ssp->port_id = pdev->id + 1;
+	}
+
+	ssp->use_count = 0;
+	ssp->of_node = dev->of_node;
+
+	mutex_lock(&ssp_lock);
+	list_add(&ssp->node, &ssp_list);
+	mutex_unlock(&ssp_lock);
+
+	platform_set_drvdata(pdev, ssp);
+
+	return 0;
+}
+
+static void pxa_ssp_remove(struct platform_device *pdev)
+{
+	struct ssp_device *ssp = platform_get_drvdata(pdev);
+
+	mutex_lock(&ssp_lock);
+	list_del(&ssp->node);
+	mutex_unlock(&ssp_lock);
+}
+
+static const struct platform_device_id ssp_id_table[] = {
+	{ "pxa25x-ssp",		PXA25x_SSP },
+	{ "pxa25x-nssp",	PXA25x_NSSP },
+	{ "pxa27x-ssp",		PXA27x_SSP },
+	{ "pxa3xx-ssp",		PXA3xx_SSP },
+	{ "pxa168-ssp",		PXA168_SSP },
+	{ "pxa910-ssp",		PXA910_SSP },
+	{ },
+};
+
+static struct platform_driver pxa_ssp_driver = {
+	.probe		= pxa_ssp_probe,
+	.remove		= pxa_ssp_remove,
+	.driver		= {
+		.name		= "pxa2xx-ssp",
+		.of_match_table	= of_match_ptr(pxa_ssp_of_ids),
+	},
+	.id_table	= ssp_id_table,
+};
+
+static int __init pxa_ssp_init(void)
+{
+	return platform_driver_register(&pxa_ssp_driver);
+}
+
+static void __exit pxa_ssp_exit(void)
+{
+	platform_driver_unregister(&pxa_ssp_driver);
+}
+
+arch_initcall(pxa_ssp_init);
+module_exit(pxa_ssp_exit);
+
+MODULE_DESCRIPTION("PXA SSP driver");
+MODULE_AUTHOR("Liam Girdwood");
+MODULE_LICENSE("GPL");