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, 173 insertions, 0 deletions

diff --git a/drivers/mfd/cs5535-mfd.c b/drivers/mfd/cs5535-mfd.c
new file mode 100644
index 000000000..f3becbef1
--- /dev/null
+++ b/drivers/mfd/cs5535-mfd.c
@@ -0,0 +1,173 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * cs5535-mfd.c - core MFD driver for CS5535/CS5536 southbridges
+ *
+ * The CS5535 and CS5536 has an ISA bridge on the PCI bus that is
+ * used for accessing GPIOs, MFGPTs, ACPI, etc.  Each subdevice has
+ * an IO range that's specified in a single BAR.  The BAR order is
+ * hardcoded in the CS553x specifications.
+ *
+ * Copyright (c) 2010  Andres Salomon <dilinger@queued.net>
+ */
+
+#include <linux/kernel.h>
+#include <linux/mfd/core.h>
+#include <linux/mfd/cs5535.h>
+#include <linux/module.h>
+#include <linux/pci.h>
+#include <linux/property.h>
+
+#include <asm/olpc.h>
+
+#define DRV_NAME "cs5535-mfd"
+
+enum cs5535_mfd_bars {
+	SMB_BAR = 0,
+	GPIO_BAR = 1,
+	MFGPT_BAR = 2,
+	PMS_BAR = 4,
+	ACPI_BAR = 5,
+	NR_BARS,
+};
+
+static struct resource cs5535_mfd_resources[NR_BARS];
+
+const struct software_node cs5535_gpio_swnode = {
+	.name = "cs5535-gpio",
+};
+EXPORT_SYMBOL_NS(cs5535_gpio_swnode, "CS5535");
+
+static struct mfd_cell cs5535_mfd_cells[] = {
+	{
+		.name = "cs5535-smb",
+		.num_resources = 1,
+		.resources = &cs5535_mfd_resources[SMB_BAR],
+	},
+	{
+		.name = "cs5535-gpio",
+		.num_resources = 1,
+		.resources = &cs5535_mfd_resources[GPIO_BAR],
+		.swnode = &cs5535_gpio_swnode,
+	},
+	{
+		.name = "cs5535-mfgpt",
+		.num_resources = 1,
+		.resources = &cs5535_mfd_resources[MFGPT_BAR],
+	},
+	{
+		.name = "cs5535-pms",
+		.num_resources = 1,
+		.resources = &cs5535_mfd_resources[PMS_BAR],
+	},
+};
+
+static struct mfd_cell cs5535_olpc_mfd_cells[] = {
+	{
+		.name = "olpc-xo1-pm-acpi",
+		.num_resources = 1,
+		.resources = &cs5535_mfd_resources[ACPI_BAR],
+	},
+	{
+		.name = "olpc-xo1-sci-acpi",
+		.num_resources = 1,
+		.resources = &cs5535_mfd_resources[ACPI_BAR],
+	},
+};
+
+static int cs5535_mfd_probe(struct pci_dev *pdev,
+		const struct pci_device_id *id)
+{
+	int err, bar;
+
+	err = pci_enable_device(pdev);
+	if (err)
+		return err;
+
+	for (bar = 0; bar < NR_BARS; bar++) {
+		struct resource *r = &cs5535_mfd_resources[bar];
+
+		r->flags = IORESOURCE_IO;
+		r->start = pci_resource_start(pdev, bar);
+		r->end = pci_resource_end(pdev, bar);
+	}
+
+	err = pci_request_region(pdev, PMS_BAR, DRV_NAME);
+	if (err) {
+		dev_err(&pdev->dev, "Failed to request PMS_BAR's IO region\n");
+		goto err_disable;
+	}
+
+	err = mfd_add_devices(&pdev->dev, PLATFORM_DEVID_NONE, cs5535_mfd_cells,
+			      ARRAY_SIZE(cs5535_mfd_cells), NULL, 0, NULL);
+	if (err) {
+		dev_err(&pdev->dev,
+			"Failed to add CS5535 sub-devices: %d\n", err);
+		goto err_release_pms;
+	}
+
+	if (machine_is_olpc()) {
+		err = pci_request_region(pdev, ACPI_BAR, DRV_NAME);
+		if (err) {
+			dev_err(&pdev->dev,
+				"Failed to request ACPI_BAR's IO region\n");
+			goto err_remove_devices;
+		}
+
+		err = mfd_add_devices(&pdev->dev, PLATFORM_DEVID_NONE,
+				      cs5535_olpc_mfd_cells,
+				      ARRAY_SIZE(cs5535_olpc_mfd_cells),
+				      NULL, 0, NULL);
+		if (err) {
+			dev_err(&pdev->dev,
+				"Failed to add CS5535 OLPC sub-devices: %d\n",
+				err);
+			goto err_release_acpi;
+		}
+	}
+
+	dev_info(&pdev->dev, "%zu devices registered.\n",
+			ARRAY_SIZE(cs5535_mfd_cells));
+
+	return 0;
+
+err_release_acpi:
+	pci_release_region(pdev, ACPI_BAR);
+err_remove_devices:
+	mfd_remove_devices(&pdev->dev);
+err_release_pms:
+	pci_release_region(pdev, PMS_BAR);
+err_disable:
+	pci_disable_device(pdev);
+	return err;
+}
+
+static void cs5535_mfd_remove(struct pci_dev *pdev)
+{
+	mfd_remove_devices(&pdev->dev);
+
+	if (machine_is_olpc())
+		pci_release_region(pdev, ACPI_BAR);
+
+	pci_release_region(pdev, PMS_BAR);
+	pci_disable_device(pdev);
+}
+
+static const struct pci_device_id cs5535_mfd_pci_tbl[] = {
+	{ PCI_DEVICE(PCI_VENDOR_ID_NS, PCI_DEVICE_ID_NS_CS5535_ISA) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_CS5536_ISA) },
+	{ 0, }
+};
+MODULE_DEVICE_TABLE(pci, cs5535_mfd_pci_tbl);
+
+static struct pci_driver cs5535_mfd_driver = {
+	.name = DRV_NAME,
+	.id_table = cs5535_mfd_pci_tbl,
+	.probe = cs5535_mfd_probe,
+	.remove = cs5535_mfd_remove,
+};
+
+module_pci_driver(cs5535_mfd_driver);
+
+MODULE_AUTHOR("Andres Salomon <dilinger@queued.net>");
+MODULE_DESCRIPTION("MFD driver for CS5535/CS5536 southbridge's ISA PCI device");
+MODULE_LICENSE("GPL");