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, 42 insertions, 0 deletions

diff --git a/fs/btrfs/root-tree.h b/fs/btrfs/root-tree.h
new file mode 100644
index 000000000..8f5739e73
--- /dev/null
+++ b/fs/btrfs/root-tree.h
@@ -0,0 +1,42 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef BTRFS_ROOT_TREE_H
+#define BTRFS_ROOT_TREE_H
+
+#include <linux/types.h>
+
+struct fscrypt_str;
+struct extent_buffer;
+struct btrfs_key;
+struct btrfs_root;
+struct btrfs_root_item;
+struct btrfs_path;
+struct btrfs_fs_info;
+struct btrfs_block_rsv;
+struct btrfs_trans_handle;
+
+int btrfs_subvolume_reserve_metadata(struct btrfs_root *root,
+				     struct btrfs_block_rsv *rsv,
+				     int nitems, bool use_global_rsv);
+int btrfs_add_root_ref(struct btrfs_trans_handle *trans, u64 root_id,
+		       u64 ref_id, u64 dirid, u64 sequence,
+		       const struct fscrypt_str *name);
+int btrfs_del_root_ref(struct btrfs_trans_handle *trans, u64 root_id,
+		       u64 ref_id, u64 dirid, u64 *sequence,
+		       const struct fscrypt_str *name);
+int btrfs_del_root(struct btrfs_trans_handle *trans, const struct btrfs_key *key);
+int btrfs_insert_root(struct btrfs_trans_handle *trans, struct btrfs_root *root,
+		      const struct btrfs_key *key,
+		      struct btrfs_root_item *item);
+int btrfs_update_root(struct btrfs_trans_handle *trans, struct btrfs_root *root,
+		      struct btrfs_key *key, struct btrfs_root_item *item);
+int btrfs_find_root(struct btrfs_root *root, const struct btrfs_key *search_key,
+		    struct btrfs_path *path, struct btrfs_root_item *root_item,
+		    struct btrfs_key *root_key);
+int btrfs_find_orphan_roots(struct btrfs_fs_info *fs_info);
+void btrfs_set_root_node(struct btrfs_root_item *item,
+			 struct extent_buffer *node);
+void btrfs_check_and_init_root_item(struct btrfs_root_item *item);
+void btrfs_update_root_times(struct btrfs_trans_handle *trans, struct btrfs_root *root);
+
+#endif