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, 167 insertions, 0 deletions

diff --git a/fs/nilfs2/sysfs.h b/fs/nilfs2/sysfs.h
new file mode 100644
index 000000000..d370cd5cc
--- /dev/null
+++ b/fs/nilfs2/sysfs.h
@@ -0,0 +1,167 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Sysfs support declarations.
+ *
+ * Copyright (C) 2005-2014 Nippon Telegraph and Telephone Corporation.
+ * Copyright (C) 2014 HGST, Inc., a Western Digital Company.
+ *
+ * Written by Vyacheslav Dubeyko <Vyacheslav.Dubeyko@hgst.com>
+ */
+
+#ifndef _NILFS_SYSFS_H
+#define _NILFS_SYSFS_H
+
+#include <linux/sysfs.h>
+
+#define NILFS_ROOT_GROUP_NAME	"nilfs2"
+
+/*
+ * struct nilfs_sysfs_dev_subgroups - device subgroup kernel objects
+ * @sg_superblock_kobj: /sys/fs/<nilfs>/<device>/superblock
+ * @sg_superblock_kobj_unregister: completion state
+ * @sg_segctor_kobj: /sys/fs/<nilfs>/<device>/segctor
+ * @sg_segctor_kobj_unregister: completion state
+ * @sg_mounted_snapshots_kobj: /sys/fs/<nilfs>/<device>/mounted_snapshots
+ * @sg_mounted_snapshots_kobj_unregister: completion state
+ * @sg_checkpoints_kobj: /sys/fs/<nilfs>/<device>/checkpoints
+ * @sg_checkpoints_kobj_unregister: completion state
+ * @sg_segments_kobj: /sys/fs/<nilfs>/<device>/segments
+ * @sg_segments_kobj_unregister: completion state
+ */
+struct nilfs_sysfs_dev_subgroups {
+	/* /sys/fs/<nilfs>/<device>/superblock */
+	struct kobject sg_superblock_kobj;
+	struct completion sg_superblock_kobj_unregister;
+
+	/* /sys/fs/<nilfs>/<device>/segctor */
+	struct kobject sg_segctor_kobj;
+	struct completion sg_segctor_kobj_unregister;
+
+	/* /sys/fs/<nilfs>/<device>/mounted_snapshots */
+	struct kobject sg_mounted_snapshots_kobj;
+	struct completion sg_mounted_snapshots_kobj_unregister;
+
+	/* /sys/fs/<nilfs>/<device>/checkpoints */
+	struct kobject sg_checkpoints_kobj;
+	struct completion sg_checkpoints_kobj_unregister;
+
+	/* /sys/fs/<nilfs>/<device>/segments */
+	struct kobject sg_segments_kobj;
+	struct completion sg_segments_kobj_unregister;
+};
+
+#define NILFS_KOBJ_ATTR_STRUCT(name) \
+struct nilfs_##name##_attr { \
+	struct attribute attr; \
+	ssize_t (*show)(struct kobject *, struct kobj_attribute *, \
+			char *); \
+	ssize_t (*store)(struct kobject *, struct kobj_attribute *, \
+			 const char *, size_t); \
+}
+
+NILFS_KOBJ_ATTR_STRUCT(feature);
+
+#define NILFS_DEV_ATTR_STRUCT(name) \
+struct nilfs_##name##_attr { \
+	struct attribute attr; \
+	ssize_t (*show)(struct nilfs_##name##_attr *, struct the_nilfs *, \
+			char *); \
+	ssize_t (*store)(struct nilfs_##name##_attr *, struct the_nilfs *, \
+			 const char *, size_t); \
+}
+
+NILFS_DEV_ATTR_STRUCT(dev);
+NILFS_DEV_ATTR_STRUCT(segments);
+NILFS_DEV_ATTR_STRUCT(mounted_snapshots);
+NILFS_DEV_ATTR_STRUCT(checkpoints);
+NILFS_DEV_ATTR_STRUCT(superblock);
+NILFS_DEV_ATTR_STRUCT(segctor);
+
+#define NILFS_CP_ATTR_STRUCT(name) \
+struct nilfs_##name##_attr { \
+	struct attribute attr; \
+	ssize_t (*show)(struct nilfs_##name##_attr *, struct nilfs_root *, \
+			char *); \
+	ssize_t (*store)(struct nilfs_##name##_attr *, struct nilfs_root *, \
+			 const char *, size_t); \
+}
+
+NILFS_CP_ATTR_STRUCT(snapshot);
+
+#define NILFS_ATTR(type, name, mode, show, store) \
+	static struct nilfs_##type##_attr nilfs_##type##_attr_##name = \
+		__ATTR(name, mode, show, store)
+
+#define NILFS_INFO_ATTR(type, name) \
+	NILFS_ATTR(type, name, 0444, NULL, NULL)
+#define NILFS_RO_ATTR(type, name) \
+	NILFS_ATTR(type, name, 0444, nilfs_##type##_##name##_show, NULL)
+#define NILFS_RW_ATTR(type, name) \
+	NILFS_ATTR(type, name, 0644, \
+		    nilfs_##type##_##name##_show, \
+		    nilfs_##type##_##name##_store)
+
+#define NILFS_FEATURE_INFO_ATTR(name) \
+	NILFS_INFO_ATTR(feature, name)
+#define NILFS_FEATURE_RO_ATTR(name) \
+	NILFS_RO_ATTR(feature, name)
+#define NILFS_FEATURE_RW_ATTR(name) \
+	NILFS_RW_ATTR(feature, name)
+
+#define NILFS_DEV_INFO_ATTR(name) \
+	NILFS_INFO_ATTR(dev, name)
+#define NILFS_DEV_RO_ATTR(name) \
+	NILFS_RO_ATTR(dev, name)
+#define NILFS_DEV_RW_ATTR(name) \
+	NILFS_RW_ATTR(dev, name)
+
+#define NILFS_SEGMENTS_RO_ATTR(name) \
+	NILFS_RO_ATTR(segments, name)
+#define NILFS_SEGMENTS_RW_ATTR(name) \
+	NILFS_RW_ATTR(segs_info, name)
+
+#define NILFS_MOUNTED_SNAPSHOTS_RO_ATTR(name) \
+	NILFS_RO_ATTR(mounted_snapshots, name)
+
+#define NILFS_CHECKPOINTS_RO_ATTR(name) \
+	NILFS_RO_ATTR(checkpoints, name)
+#define NILFS_CHECKPOINTS_RW_ATTR(name) \
+	NILFS_RW_ATTR(checkpoints, name)
+
+#define NILFS_SNAPSHOT_INFO_ATTR(name) \
+	NILFS_INFO_ATTR(snapshot, name)
+#define NILFS_SNAPSHOT_RO_ATTR(name) \
+	NILFS_RO_ATTR(snapshot, name)
+#define NILFS_SNAPSHOT_RW_ATTR(name) \
+	NILFS_RW_ATTR(snapshot, name)
+
+#define NILFS_SUPERBLOCK_RO_ATTR(name) \
+	NILFS_RO_ATTR(superblock, name)
+#define NILFS_SUPERBLOCK_RW_ATTR(name) \
+	NILFS_RW_ATTR(superblock, name)
+
+#define NILFS_SEGCTOR_INFO_ATTR(name) \
+	NILFS_INFO_ATTR(segctor, name)
+#define NILFS_SEGCTOR_RO_ATTR(name) \
+	NILFS_RO_ATTR(segctor, name)
+#define NILFS_SEGCTOR_RW_ATTR(name) \
+	NILFS_RW_ATTR(segctor, name)
+
+#define NILFS_FEATURE_ATTR_LIST(name) \
+	(&nilfs_feature_attr_##name.attr)
+#define NILFS_DEV_ATTR_LIST(name) \
+	(&nilfs_dev_attr_##name.attr)
+#define NILFS_SEGMENTS_ATTR_LIST(name) \
+	(&nilfs_segments_attr_##name.attr)
+#define NILFS_MOUNTED_SNAPSHOTS_ATTR_LIST(name) \
+	(&nilfs_mounted_snapshots_attr_##name.attr)
+#define NILFS_CHECKPOINTS_ATTR_LIST(name) \
+	(&nilfs_checkpoints_attr_##name.attr)
+#define NILFS_SNAPSHOT_ATTR_LIST(name) \
+	(&nilfs_snapshot_attr_##name.attr)
+#define NILFS_SUPERBLOCK_ATTR_LIST(name) \
+	(&nilfs_superblock_attr_##name.attr)
+#define NILFS_SEGCTOR_ATTR_LIST(name) \
+	(&nilfs_segctor_attr_##name.attr)
+
+#endif /* _NILFS_SYSFS_H */