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, 250 insertions, 0 deletions

diff --git a/drivers/block/rnbd/rnbd-srv-sysfs.c b/drivers/block/rnbd/rnbd-srv-sysfs.c
new file mode 100644
index 000000000..647800944
--- /dev/null
+++ b/drivers/block/rnbd/rnbd-srv-sysfs.c
@@ -0,0 +1,250 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * RDMA Network Block Driver
+ *
+ * Copyright (c) 2014 - 2018 ProfitBricks GmbH. All rights reserved.
+ * Copyright (c) 2018 - 2019 1&1 IONOS Cloud GmbH. All rights reserved.
+ * Copyright (c) 2019 - 2020 1&1 IONOS SE. All rights reserved.
+ */
+#undef pr_fmt
+#define pr_fmt(fmt) KBUILD_MODNAME " L" __stringify(__LINE__) ": " fmt
+
+#include <linux/kobject.h>
+#include <linux/sysfs.h>
+#include <linux/stat.h>
+#include <linux/list.h>
+#include <linux/moduleparam.h>
+#include <linux/device.h>
+
+#include "rnbd-srv.h"
+
+static struct device *rnbd_dev;
+static const struct class rnbd_dev_class = {
+	.name = "rnbd-server",
+};
+static struct kobject *rnbd_devs_kobj;
+
+static void rnbd_srv_dev_release(struct kobject *kobj)
+{
+	struct rnbd_srv_dev *dev;
+
+	dev = container_of(kobj, struct rnbd_srv_dev, dev_kobj);
+
+	kfree(dev);
+}
+
+static const struct kobj_type dev_ktype = {
+	.sysfs_ops = &kobj_sysfs_ops,
+	.release = rnbd_srv_dev_release
+};
+
+int rnbd_srv_create_dev_sysfs(struct rnbd_srv_dev *dev,
+			       struct block_device *bdev)
+{
+	struct kobject *bdev_kobj;
+	int ret;
+
+	ret = kobject_init_and_add(&dev->dev_kobj, &dev_ktype,
+				   rnbd_devs_kobj, "%pg", bdev);
+	if (ret) {
+		kobject_put(&dev->dev_kobj);
+		return ret;
+	}
+
+	dev->dev_sessions_kobj = kobject_create_and_add("sessions",
+							&dev->dev_kobj);
+	if (!dev->dev_sessions_kobj) {
+		ret = -ENOMEM;
+		goto free_dev_kobj;
+	}
+
+	bdev_kobj = &disk_to_dev(bdev->bd_disk)->kobj;
+	ret = sysfs_create_link(&dev->dev_kobj, bdev_kobj, "block_dev");
+	if (ret)
+		goto put_sess_kobj;
+
+	return 0;
+
+put_sess_kobj:
+	kobject_put(dev->dev_sessions_kobj);
+free_dev_kobj:
+	kobject_del(&dev->dev_kobj);
+	kobject_put(&dev->dev_kobj);
+	return ret;
+}
+
+void rnbd_srv_destroy_dev_sysfs(struct rnbd_srv_dev *dev)
+{
+	sysfs_remove_link(&dev->dev_kobj, "block_dev");
+	kobject_del(dev->dev_sessions_kobj);
+	kobject_put(dev->dev_sessions_kobj);
+	kobject_del(&dev->dev_kobj);
+	kobject_put(&dev->dev_kobj);
+}
+
+static ssize_t read_only_show(struct kobject *kobj, struct kobj_attribute *attr,
+			      char *page)
+{
+	struct rnbd_srv_sess_dev *sess_dev;
+
+	sess_dev = container_of(kobj, struct rnbd_srv_sess_dev, kobj);
+
+	return sysfs_emit(page, "%d\n", sess_dev->readonly);
+}
+
+static struct kobj_attribute rnbd_srv_dev_session_ro_attr =
+	__ATTR_RO(read_only);
+
+static ssize_t access_mode_show(struct kobject *kobj,
+				struct kobj_attribute *attr,
+				char *page)
+{
+	struct rnbd_srv_sess_dev *sess_dev;
+
+	sess_dev = container_of(kobj, struct rnbd_srv_sess_dev, kobj);
+
+	return sysfs_emit(page, "%s\n",
+			  rnbd_access_modes[sess_dev->access_mode].str);
+}
+
+static struct kobj_attribute rnbd_srv_dev_session_access_mode_attr =
+	__ATTR_RO(access_mode);
+
+static ssize_t mapping_path_show(struct kobject *kobj,
+				 struct kobj_attribute *attr, char *page)
+{
+	struct rnbd_srv_sess_dev *sess_dev;
+
+	sess_dev = container_of(kobj, struct rnbd_srv_sess_dev, kobj);
+
+	return sysfs_emit(page, "%s\n", sess_dev->pathname);
+}
+
+static struct kobj_attribute rnbd_srv_dev_session_mapping_path_attr =
+	__ATTR_RO(mapping_path);
+
+static ssize_t rnbd_srv_dev_session_force_close_show(struct kobject *kobj,
+					struct kobj_attribute *attr, char *page)
+{
+	return sysfs_emit(page, "Usage: echo 1 > %s\n",
+			  attr->attr.name);
+}
+
+static ssize_t rnbd_srv_dev_session_force_close_store(struct kobject *kobj,
+					struct kobj_attribute *attr,
+					const char *buf, size_t count)
+{
+	struct rnbd_srv_sess_dev *sess_dev;
+
+	sess_dev = container_of(kobj, struct rnbd_srv_sess_dev, kobj);
+
+	if (!sysfs_streq(buf, "1")) {
+		rnbd_srv_err(sess_dev, "%s: invalid value: '%s'\n",
+			      attr->attr.name, buf);
+		return -EINVAL;
+	}
+
+	rnbd_srv_info(sess_dev, "force close requested\n");
+	rnbd_srv_sess_dev_force_close(sess_dev, attr);
+
+	return count;
+}
+
+static struct kobj_attribute rnbd_srv_dev_session_force_close_attr =
+	__ATTR(force_close, 0644,
+	       rnbd_srv_dev_session_force_close_show,
+	       rnbd_srv_dev_session_force_close_store);
+
+static struct attribute *rnbd_srv_default_dev_sessions_attrs[] = {
+	&rnbd_srv_dev_session_access_mode_attr.attr,
+	&rnbd_srv_dev_session_ro_attr.attr,
+	&rnbd_srv_dev_session_mapping_path_attr.attr,
+	&rnbd_srv_dev_session_force_close_attr.attr,
+	NULL,
+};
+
+static struct attribute_group rnbd_srv_default_dev_session_attr_group = {
+	.attrs = rnbd_srv_default_dev_sessions_attrs,
+};
+
+void rnbd_srv_destroy_dev_session_sysfs(struct rnbd_srv_sess_dev *sess_dev)
+{
+	sysfs_remove_group(&sess_dev->kobj,
+			   &rnbd_srv_default_dev_session_attr_group);
+
+	kobject_del(&sess_dev->kobj);
+	kobject_put(&sess_dev->kobj);
+}
+
+static void rnbd_srv_sess_dev_release(struct kobject *kobj)
+{
+	struct rnbd_srv_sess_dev *sess_dev;
+
+	sess_dev = container_of(kobj, struct rnbd_srv_sess_dev, kobj);
+	rnbd_destroy_sess_dev(sess_dev, sess_dev->keep_id);
+}
+
+static const struct kobj_type rnbd_srv_sess_dev_ktype = {
+	.sysfs_ops	= &kobj_sysfs_ops,
+	.release	= rnbd_srv_sess_dev_release,
+};
+
+int rnbd_srv_create_dev_session_sysfs(struct rnbd_srv_sess_dev *sess_dev)
+{
+	int ret;
+
+	ret = kobject_init_and_add(&sess_dev->kobj, &rnbd_srv_sess_dev_ktype,
+				   sess_dev->dev->dev_sessions_kobj, "%s",
+				   sess_dev->sess->sessname);
+	if (ret) {
+		kobject_put(&sess_dev->kobj);
+		return ret;
+	}
+
+	ret = sysfs_create_group(&sess_dev->kobj,
+				 &rnbd_srv_default_dev_session_attr_group);
+	if (ret) {
+		kobject_del(&sess_dev->kobj);
+		kobject_put(&sess_dev->kobj);
+	}
+
+	return ret;
+}
+
+int rnbd_srv_create_sysfs_files(void)
+{
+	int err;
+
+	err = class_register(&rnbd_dev_class);
+	if (err)
+		return err;
+
+	rnbd_dev = device_create(&rnbd_dev_class, NULL,
+				 MKDEV(0, 0), NULL, "ctl");
+	if (IS_ERR(rnbd_dev)) {
+		err = PTR_ERR(rnbd_dev);
+		goto cls_destroy;
+	}
+	rnbd_devs_kobj = kobject_create_and_add("devices", &rnbd_dev->kobj);
+	if (!rnbd_devs_kobj) {
+		err = -ENOMEM;
+		goto dev_destroy;
+	}
+
+	return 0;
+
+dev_destroy:
+	device_destroy(&rnbd_dev_class, MKDEV(0, 0));
+cls_destroy:
+	class_unregister(&rnbd_dev_class);
+
+	return err;
+}
+
+void rnbd_srv_destroy_sysfs_files(void)
+{
+	kobject_del(rnbd_devs_kobj);
+	kobject_put(rnbd_devs_kobj);
+	device_destroy(&rnbd_dev_class, MKDEV(0, 0));
+	class_unregister(&rnbd_dev_class);
+}