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, 432 insertions, 0 deletions

diff --git a/drivers/pnp/card.c b/drivers/pnp/card.c
new file mode 100644
index 000000000..df5e3d3cb
--- /dev/null
+++ b/drivers/pnp/card.c
@@ -0,0 +1,432 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * card.c - contains functions for managing groups of PnP devices
+ *
+ * Copyright 2002 Adam Belay <ambx1@neo.rr.com>
+ */
+
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/ctype.h>
+#include <linux/slab.h>
+#include <linux/pnp.h>
+#include <linux/dma-mapping.h>
+#include "base.h"
+
+LIST_HEAD(pnp_cards);
+static LIST_HEAD(pnp_card_drivers);
+
+static const struct pnp_card_device_id *match_card(struct pnp_card_driver *drv,
+						   struct pnp_card *card)
+{
+	const struct pnp_card_device_id *drv_id = drv->id_table;
+
+	while (*drv_id->id) {
+		if (compare_pnp_id(card->id, drv_id->id)) {
+			int i = 0;
+
+			for (;;) {
+				int found;
+				struct pnp_dev *dev;
+
+				if (i == PNP_MAX_DEVICES ||
+				    !*drv_id->devs[i].id)
+					return drv_id;
+				found = 0;
+				card_for_each_dev(card, dev) {
+					if (compare_pnp_id(dev->id,
+						   drv_id->devs[i].id)) {
+						found = 1;
+						break;
+					}
+				}
+				if (!found)
+					break;
+				i++;
+			}
+		}
+		drv_id++;
+	}
+	return NULL;
+}
+
+static void card_remove(struct pnp_dev *dev)
+{
+	dev->card_link = NULL;
+}
+
+static void card_remove_first(struct pnp_dev *dev)
+{
+	struct pnp_card_driver *drv = to_pnp_card_driver(dev->driver);
+
+	if (!dev->card || !drv)
+		return;
+	if (drv->remove)
+		drv->remove(dev->card_link);
+	drv->link.remove = &card_remove;
+	kfree(dev->card_link);
+	card_remove(dev);
+}
+
+static int card_probe(struct pnp_card *card, struct pnp_card_driver *drv)
+{
+	const struct pnp_card_device_id *id;
+	struct pnp_card_link *clink;
+	struct pnp_dev *dev;
+
+	if (!drv->probe)
+		return 0;
+	id = match_card(drv, card);
+	if (!id)
+		return 0;
+
+	clink = kzalloc_obj(*clink);
+	if (!clink)
+		return 0;
+	clink->card = card;
+	clink->driver = drv;
+	clink->pm_state = PMSG_ON;
+
+	if (drv->probe(clink, id) >= 0)
+		return 1;
+
+	/* Recovery */
+	card_for_each_dev(card, dev) {
+		if (dev->card_link == clink)
+			pnp_release_card_device(dev);
+	}
+	kfree(clink);
+	return 0;
+}
+
+/**
+ * pnp_add_card_id - adds an EISA id to the specified card
+ * @id: pointer to a pnp_id structure
+ * @card: pointer to the desired card
+ */
+static struct pnp_id *pnp_add_card_id(struct pnp_card *card, char *id)
+{
+	struct pnp_id *dev_id, *ptr;
+
+	dev_id = kzalloc_obj(struct pnp_id);
+	if (!dev_id)
+		return NULL;
+
+	dev_id->id[0] = id[0];
+	dev_id->id[1] = id[1];
+	dev_id->id[2] = id[2];
+	dev_id->id[3] = tolower(id[3]);
+	dev_id->id[4] = tolower(id[4]);
+	dev_id->id[5] = tolower(id[5]);
+	dev_id->id[6] = tolower(id[6]);
+	dev_id->id[7] = '\0';
+
+	dev_id->next = NULL;
+	ptr = card->id;
+	while (ptr && ptr->next)
+		ptr = ptr->next;
+	if (ptr)
+		ptr->next = dev_id;
+	else
+		card->id = dev_id;
+
+	return dev_id;
+}
+
+static void pnp_free_card_ids(struct pnp_card *card)
+{
+	struct pnp_id *id;
+	struct pnp_id *next;
+
+	id = card->id;
+	while (id) {
+		next = id->next;
+		kfree(id);
+		id = next;
+	}
+}
+
+static void pnp_release_card(struct device *dmdev)
+{
+	struct pnp_card *card = to_pnp_card(dmdev);
+
+	pnp_free_card_ids(card);
+	kfree(card);
+}
+
+struct pnp_card *pnp_alloc_card(struct pnp_protocol *protocol, int id, char *pnpid)
+{
+	struct pnp_card *card;
+	struct pnp_id *dev_id;
+
+	card = kzalloc_obj(struct pnp_card);
+	if (!card)
+		return NULL;
+
+	card->protocol = protocol;
+	card->number = id;
+
+	card->dev.parent = &card->protocol->dev;
+	dev_set_name(&card->dev, "%02x:%02x", card->protocol->number, card->number);
+
+	card->dev.coherent_dma_mask = DMA_BIT_MASK(24);
+	card->dev.dma_mask = &card->dev.coherent_dma_mask;
+
+	dev_id = pnp_add_card_id(card, pnpid);
+	if (!dev_id) {
+		kfree(card);
+		return NULL;
+	}
+
+	return card;
+}
+
+static ssize_t name_show(struct device *dmdev,
+			 struct device_attribute *attr, char *buf)
+{
+	char *str = buf;
+	struct pnp_card *card = to_pnp_card(dmdev);
+
+	str += sprintf(str, "%s\n", card->name);
+	return (str - buf);
+}
+
+static DEVICE_ATTR_RO(name);
+
+static ssize_t card_id_show(struct device *dmdev,
+			    struct device_attribute *attr, char *buf)
+{
+	char *str = buf;
+	struct pnp_card *card = to_pnp_card(dmdev);
+	struct pnp_id *pos = card->id;
+
+	while (pos) {
+		str += sprintf(str, "%s\n", pos->id);
+		pos = pos->next;
+	}
+	return (str - buf);
+}
+
+static DEVICE_ATTR_RO(card_id);
+
+static int pnp_interface_attach_card(struct pnp_card *card)
+{
+	int rc = device_create_file(&card->dev, &dev_attr_name);
+
+	if (rc)
+		return rc;
+
+	rc = device_create_file(&card->dev, &dev_attr_card_id);
+	if (rc)
+		goto err_name;
+
+	return 0;
+
+err_name:
+	device_remove_file(&card->dev, &dev_attr_name);
+	return rc;
+}
+
+/**
+ * pnp_add_card - adds a PnP card to the PnP Layer
+ * @card: pointer to the card to add
+ */
+int pnp_add_card(struct pnp_card *card)
+{
+	int error;
+	struct list_head *pos, *temp;
+
+	card->dev.bus = NULL;
+	card->dev.release = &pnp_release_card;
+	error = device_register(&card->dev);
+	if (error) {
+		dev_err(&card->dev, "could not register (err=%d)\n", error);
+		put_device(&card->dev);
+		return error;
+	}
+
+	pnp_interface_attach_card(card);
+	mutex_lock(&pnp_lock);
+	list_add_tail(&card->global_list, &pnp_cards);
+	list_add_tail(&card->protocol_list, &card->protocol->cards);
+	mutex_unlock(&pnp_lock);
+
+	/* we wait until now to add devices in order to ensure the drivers
+	 * will be able to use all of the related devices on the card
+	 * without waiting an unreasonable length of time */
+	list_for_each_safe(pos, temp, &card->devices) {
+		struct pnp_dev *dev = card_to_pnp_dev(pos);
+		error = __pnp_add_device(dev);
+		if (error) {
+			mutex_lock(&pnp_lock);
+			list_del(&dev->card_list);
+			dev->card = NULL;
+			mutex_unlock(&pnp_lock);
+			put_device(&dev->dev);
+		}
+	}
+
+	/* match with card drivers */
+	list_for_each_safe(pos, temp, &pnp_card_drivers) {
+		struct pnp_card_driver *drv =
+		    list_entry(pos, struct pnp_card_driver,
+			       global_list);
+		card_probe(card, drv);
+	}
+	return 0;
+}
+
+/**
+ * pnp_add_card_device - adds a device to the specified card
+ * @card: pointer to the card to add to
+ * @dev: pointer to the device to add
+ */
+int pnp_add_card_device(struct pnp_card *card, struct pnp_dev *dev)
+{
+	dev->dev.parent = &card->dev;
+	dev->card_link = NULL;
+	dev_set_name(&dev->dev, "%02x:%02x.%02x",
+		     dev->protocol->number, card->number, dev->number);
+	mutex_lock(&pnp_lock);
+	dev->card = card;
+	list_add_tail(&dev->card_list, &card->devices);
+	mutex_unlock(&pnp_lock);
+	return 0;
+}
+
+/**
+ * pnp_request_card_device - Searches for a PnP device under the specified card
+ * @clink: pointer to the card link, cannot be NULL
+ * @id: pointer to a PnP ID structure that explains the rules for finding the device
+ * @from: Starting place to search from. If NULL it will start from the beginning.
+ */
+struct pnp_dev *pnp_request_card_device(struct pnp_card_link *clink,
+					const char *id, struct pnp_dev *from)
+{
+	struct list_head *pos;
+	struct pnp_dev *dev;
+	struct pnp_card_driver *drv;
+	struct pnp_card *card;
+
+	if (!clink || !id)
+		return NULL;
+
+	card = clink->card;
+	drv = clink->driver;
+	if (!from) {
+		pos = card->devices.next;
+	} else {
+		if (from->card != card)
+			return NULL;
+		pos = from->card_list.next;
+	}
+	while (pos != &card->devices) {
+		dev = card_to_pnp_dev(pos);
+		if ((!dev->card_link) && compare_pnp_id(dev->id, id))
+			goto found;
+		pos = pos->next;
+	}
+
+	return NULL;
+
+found:
+	dev->card_link = clink;
+	dev->dev.driver = &drv->link.driver;
+	if (pnp_bus_type.probe(&dev->dev))
+		goto err_out;
+	if (device_bind_driver(&dev->dev))
+		goto err_out;
+
+	return dev;
+
+err_out:
+	dev->dev.driver = NULL;
+	dev->card_link = NULL;
+	return NULL;
+}
+EXPORT_SYMBOL(pnp_request_card_device);
+
+/**
+ * pnp_release_card_device - call this when the driver no longer needs the device
+ * @dev: pointer to the PnP device structure
+ */
+void pnp_release_card_device(struct pnp_dev *dev)
+{
+	struct pnp_card_driver *drv = dev->card_link->driver;
+
+	drv->link.remove = &card_remove;
+	device_release_driver(&dev->dev);
+	drv->link.remove = &card_remove_first;
+}
+EXPORT_SYMBOL(pnp_release_card_device);
+
+/*
+ * suspend/resume callbacks
+ */
+static int card_suspend(struct pnp_dev *dev, pm_message_t state)
+{
+	struct pnp_card_link *link = dev->card_link;
+
+	if (link->pm_state.event == state.event)
+		return 0;
+	link->pm_state = state;
+	return link->driver->suspend(link, state);
+}
+
+static int card_resume(struct pnp_dev *dev)
+{
+	struct pnp_card_link *link = dev->card_link;
+
+	if (link->pm_state.event == PM_EVENT_ON)
+		return 0;
+	link->pm_state = PMSG_ON;
+	link->driver->resume(link);
+	return 0;
+}
+
+/**
+ * pnp_register_card_driver - registers a PnP card driver with the PnP Layer
+ * @drv: pointer to the driver to register
+ */
+int pnp_register_card_driver(struct pnp_card_driver *drv)
+{
+	int error;
+	struct list_head *pos, *temp;
+
+	drv->link.name = drv->name;
+	drv->link.id_table = NULL;	/* this will disable auto matching */
+	drv->link.flags = drv->flags;
+	drv->link.probe = NULL;
+	drv->link.remove = &card_remove_first;
+	drv->link.suspend = drv->suspend ? card_suspend : NULL;
+	drv->link.resume = drv->resume ? card_resume : NULL;
+
+	error = pnp_register_driver(&drv->link);
+	if (error < 0)
+		return error;
+
+	mutex_lock(&pnp_lock);
+	list_add_tail(&drv->global_list, &pnp_card_drivers);
+	mutex_unlock(&pnp_lock);
+
+	list_for_each_safe(pos, temp, &pnp_cards) {
+		struct pnp_card *card =
+		    list_entry(pos, struct pnp_card, global_list);
+		card_probe(card, drv);
+	}
+	return 0;
+}
+EXPORT_SYMBOL(pnp_register_card_driver);
+
+/**
+ * pnp_unregister_card_driver - unregisters a PnP card driver from the PnP Layer
+ * @drv: pointer to the driver to unregister
+ */
+void pnp_unregister_card_driver(struct pnp_card_driver *drv)
+{
+	mutex_lock(&pnp_lock);
+	list_del(&drv->global_list);
+	mutex_unlock(&pnp_lock);
+	pnp_unregister_driver(&drv->link);
+}
+EXPORT_SYMBOL(pnp_unregister_card_driver);