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, 267 insertions, 0 deletions

diff --git a/drivers/scsi/raid_class.c b/drivers/scsi/raid_class.c
new file mode 100644
index 000000000..94f76e358
--- /dev/null
+++ b/drivers/scsi/raid_class.c
@@ -0,0 +1,267 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * raid_class.c - implementation of a simple raid visualisation class
+ *
+ * Copyright (c) 2005 - James Bottomley <James.Bottomley@steeleye.com>
+ *
+ * This class is designed to allow raid attributes to be visualised and
+ * manipulated in a form independent of the underlying raid.  Ultimately this
+ * should work for both hardware and software raids.
+ */
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/list.h>
+#include <linux/slab.h>
+#include <linux/string.h>
+#include <linux/raid_class.h>
+#include <scsi/scsi_device.h>
+#include <scsi/scsi_host.h>
+
+#define RAID_NUM_ATTRS	3
+
+struct raid_internal {
+	struct raid_template r;
+	struct raid_function_template *f;
+	/* The actual attributes */
+	struct device_attribute private_attrs[RAID_NUM_ATTRS];
+	/* The array of null terminated pointers to attributes 
+	 * needed by scsi_sysfs.c */
+	struct device_attribute *attrs[RAID_NUM_ATTRS + 1];
+};
+
+struct raid_component {
+	struct list_head node;
+	struct device dev;
+	int num;
+};
+
+#define to_raid_internal(tmpl)	container_of(tmpl, struct raid_internal, r)
+
+#define tc_to_raid_internal(tcont) ({					\
+	struct raid_template *r =					\
+		container_of(tcont, struct raid_template, raid_attrs);	\
+	to_raid_internal(r);						\
+})
+
+#define ac_to_raid_internal(acont) ({					\
+	struct transport_container *tc =				\
+		container_of(acont, struct transport_container, ac);	\
+	tc_to_raid_internal(tc);					\
+})
+
+#define device_to_raid_internal(dev) ({				\
+	struct attribute_container *ac =				\
+		attribute_container_classdev_to_container(dev);	\
+	ac_to_raid_internal(ac);					\
+})
+	
+
+static int raid_match(struct attribute_container *cont, struct device *dev)
+{
+	/* We have to look for every subsystem that could house
+	 * emulated RAID devices, so start with SCSI */
+	struct raid_internal *i = ac_to_raid_internal(cont);
+
+	if (IS_ENABLED(CONFIG_SCSI) && scsi_is_sdev_device(dev)) {
+		struct scsi_device *sdev = to_scsi_device(dev);
+
+		if (i->f->cookie != sdev->host->hostt)
+			return 0;
+
+		return i->f->is_raid(dev);
+	}
+	/* FIXME: look at other subsystems too */
+	return 0;
+}
+
+static int raid_setup(struct transport_container *tc, struct device *dev,
+		       struct device *cdev)
+{
+	struct raid_data *rd;
+
+	BUG_ON(dev_get_drvdata(cdev));
+
+	rd = kzalloc_obj(*rd);
+	if (!rd)
+		return -ENOMEM;
+
+	INIT_LIST_HEAD(&rd->component_list);
+	dev_set_drvdata(cdev, rd);
+		
+	return 0;
+}
+
+static int raid_remove(struct transport_container *tc, struct device *dev,
+		       struct device *cdev)
+{
+	struct raid_data *rd = dev_get_drvdata(cdev);
+	struct raid_component *rc, *next;
+	dev_printk(KERN_ERR, dev, "RAID REMOVE\n");
+	dev_set_drvdata(cdev, NULL);
+	list_for_each_entry_safe(rc, next, &rd->component_list, node) {
+		list_del(&rc->node);
+		dev_printk(KERN_ERR, rc->dev.parent, "RAID COMPONENT REMOVE\n");
+		device_unregister(&rc->dev);
+	}
+	dev_printk(KERN_ERR, dev, "RAID REMOVE DONE\n");
+	kfree(rd);
+	return 0;
+}
+
+static DECLARE_TRANSPORT_CLASS(raid_class,
+			       "raid_devices",
+			       raid_setup,
+			       raid_remove,
+			       NULL);
+
+static const struct {
+	enum raid_state	value;
+	char		*name;
+} raid_states[] = {
+	{ RAID_STATE_UNKNOWN, "unknown" },
+	{ RAID_STATE_ACTIVE, "active" },
+	{ RAID_STATE_DEGRADED, "degraded" },
+	{ RAID_STATE_RESYNCING, "resyncing" },
+	{ RAID_STATE_OFFLINE, "offline" },
+};
+
+static const char *raid_state_name(enum raid_state state)
+{
+	int i;
+	char *name = NULL;
+
+	for (i = 0; i < ARRAY_SIZE(raid_states); i++) {
+		if (raid_states[i].value == state) {
+			name = raid_states[i].name;
+			break;
+		}
+	}
+	return name;
+}
+
+static struct {
+	enum raid_level value;
+	char *name;
+} raid_levels[] = {
+	{ RAID_LEVEL_UNKNOWN, "unknown" },
+	{ RAID_LEVEL_LINEAR, "linear" },
+	{ RAID_LEVEL_0, "raid0" },
+	{ RAID_LEVEL_1, "raid1" },
+	{ RAID_LEVEL_10, "raid10" },
+	{ RAID_LEVEL_1E, "raid1e" },
+	{ RAID_LEVEL_3, "raid3" },
+	{ RAID_LEVEL_4, "raid4" },
+	{ RAID_LEVEL_5, "raid5" },
+	{ RAID_LEVEL_50, "raid50" },
+	{ RAID_LEVEL_6, "raid6" },
+	{ RAID_LEVEL_JBOD, "jbod" },
+};
+
+static const char *raid_level_name(enum raid_level level)
+{
+	int i;
+	char *name = NULL;
+
+	for (i = 0; i < ARRAY_SIZE(raid_levels); i++) {
+		if (raid_levels[i].value == level) {
+			name = raid_levels[i].name;
+			break;
+		}
+	}
+	return name;
+}
+
+#define raid_attr_show_internal(attr, fmt, var, code)			\
+static ssize_t raid_show_##attr(struct device *dev, 			\
+				struct device_attribute *attr, 		\
+				char *buf)				\
+{									\
+	struct raid_data *rd = dev_get_drvdata(dev);			\
+	code								\
+	return snprintf(buf, 20, #fmt "\n", var);			\
+}
+
+#define raid_attr_ro_states(attr, states, code)				\
+raid_attr_show_internal(attr, %s, name,					\
+	const char *name;						\
+	code								\
+	name = raid_##states##_name(rd->attr);				\
+)									\
+static DEVICE_ATTR(attr, S_IRUGO, raid_show_##attr, NULL)
+
+
+#define raid_attr_ro_internal(attr, code)				\
+raid_attr_show_internal(attr, %d, rd->attr, code)			\
+static DEVICE_ATTR(attr, S_IRUGO, raid_show_##attr, NULL)
+
+#define ATTR_CODE(attr)							\
+	struct raid_internal *i = device_to_raid_internal(dev);		\
+	if (i->f->get_##attr)						\
+		i->f->get_##attr(dev->parent);
+
+#define raid_attr_ro(attr)	raid_attr_ro_internal(attr, )
+#define raid_attr_ro_fn(attr)	raid_attr_ro_internal(attr, ATTR_CODE(attr))
+#define raid_attr_ro_state(attr)	raid_attr_ro_states(attr, attr, )
+#define raid_attr_ro_state_fn(attr)	raid_attr_ro_states(attr, attr, ATTR_CODE(attr))
+
+
+raid_attr_ro_state(level);
+raid_attr_ro_fn(resync);
+raid_attr_ro_state_fn(state);
+
+struct raid_template *
+raid_class_attach(struct raid_function_template *ft)
+{
+	struct raid_internal *i = kzalloc_obj(struct raid_internal);
+	int count = 0;
+
+	if (unlikely(!i))
+		return NULL;
+
+	i->f = ft;
+
+	i->r.raid_attrs.ac.class = &raid_class.class;
+	i->r.raid_attrs.ac.match = raid_match;
+	i->r.raid_attrs.ac.attrs = &i->attrs[0];
+
+	attribute_container_register(&i->r.raid_attrs.ac);
+
+	i->attrs[count++] = &dev_attr_level;
+	i->attrs[count++] = &dev_attr_resync;
+	i->attrs[count++] = &dev_attr_state;
+
+	i->attrs[count] = NULL;
+	BUG_ON(count > RAID_NUM_ATTRS);
+
+	return &i->r;
+}
+EXPORT_SYMBOL(raid_class_attach);
+
+void
+raid_class_release(struct raid_template *r)
+{
+	struct raid_internal *i = to_raid_internal(r);
+
+	BUG_ON(attribute_container_unregister(&i->r.raid_attrs.ac));
+
+	kfree(i);
+}
+EXPORT_SYMBOL(raid_class_release);
+
+static __init int raid_init(void)
+{
+	return transport_class_register(&raid_class);
+}
+
+static __exit void raid_exit(void)
+{
+	transport_class_unregister(&raid_class);
+}
+
+MODULE_AUTHOR("James Bottomley");
+MODULE_DESCRIPTION("RAID device class");
+MODULE_LICENSE("GPL");
+
+module_init(raid_init);
+module_exit(raid_exit);
+