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, 65 insertions, 0 deletions

diff --git a/fs/nilfs2/btree.h b/fs/nilfs2/btree.h
new file mode 100644
index 000000000..2a220f716
--- /dev/null
+++ b/fs/nilfs2/btree.h
@@ -0,0 +1,65 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * NILFS B-tree.
+ *
+ * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
+ *
+ * Written by Koji Sato.
+ */
+
+#ifndef _NILFS_BTREE_H
+#define _NILFS_BTREE_H
+
+#include <linux/types.h>
+#include <linux/buffer_head.h>
+#include <linux/list.h>
+#include <linux/nilfs2_ondisk.h>	/* nilfs_btree_node */
+#include "btnode.h"
+#include "bmap.h"
+
+/**
+ * struct nilfs_btree_path - A path on which B-tree operations are executed
+ * @bp_bh: buffer head of node block
+ * @bp_sib_bh: buffer head of sibling node block
+ * @bp_index: index of child node
+ * @bp_oldreq: ptr end request for old ptr
+ * @bp_newreq: ptr alloc request for new ptr
+ * @bp_ctxt: context information for changing the key of a b-tree node block
+ * @bp_op: rebalance operation
+ */
+struct nilfs_btree_path {
+	struct buffer_head *bp_bh;
+	struct buffer_head *bp_sib_bh;
+	int bp_index;
+	union nilfs_bmap_ptr_req bp_oldreq;
+	union nilfs_bmap_ptr_req bp_newreq;
+	struct nilfs_btnode_chkey_ctxt bp_ctxt;
+	void (*bp_op)(struct nilfs_bmap *, struct nilfs_btree_path *,
+		      int, __u64 *, __u64 *);
+};
+
+#define NILFS_BTREE_ROOT_SIZE		NILFS_BMAP_SIZE
+#define NILFS_BTREE_ROOT_NCHILDREN_MAX					\
+	((NILFS_BTREE_ROOT_SIZE - sizeof(struct nilfs_btree_node)) /	\
+	 (sizeof(__le64 /* dkey */) + sizeof(__le64 /* dptr */)))
+#define NILFS_BTREE_ROOT_NCHILDREN_MIN	0
+#define NILFS_BTREE_NODE_EXTRA_PAD_SIZE	(sizeof(__le64))
+#define NILFS_BTREE_NODE_NCHILDREN_MAX(nodesize)			\
+	(((nodesize) - sizeof(struct nilfs_btree_node) -		\
+		NILFS_BTREE_NODE_EXTRA_PAD_SIZE) /			\
+	 (sizeof(__le64 /* dkey */) + sizeof(__le64 /* dptr */)))
+#define NILFS_BTREE_NODE_NCHILDREN_MIN(nodesize)			\
+	((NILFS_BTREE_NODE_NCHILDREN_MAX(nodesize) - 1) / 2 + 1)
+#define NILFS_BTREE_KEY_MIN	((__u64)0)
+#define NILFS_BTREE_KEY_MAX	(~(__u64)0)
+
+extern struct kmem_cache *nilfs_btree_path_cache;
+
+int nilfs_btree_init(struct nilfs_bmap *);
+int nilfs_btree_convert_and_insert(struct nilfs_bmap *, __u64, __u64,
+				   const __u64 *, const __u64 *, int);
+void nilfs_btree_init_gc(struct nilfs_bmap *);
+
+int nilfs_btree_broken_node_block(struct buffer_head *bh);
+
+#endif	/* _NILFS_BTREE_H */