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, 69 insertions, 0 deletions

diff --git a/fs/omfs/omfs.h b/fs/omfs/omfs.h
new file mode 100644
index 000000000..4008be73d
--- /dev/null
+++ b/fs/omfs/omfs.h
@@ -0,0 +1,69 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _OMFS_H
+#define _OMFS_H
+
+#include <linux/module.h>
+#include <linux/fs.h>
+
+#include "omfs_fs.h"
+
+/* In-memory structures */
+struct omfs_sb_info {
+	u64 s_num_blocks;
+	u64 s_bitmap_ino;
+	u64 s_root_ino;
+	u32 s_blocksize;
+	u32 s_mirrors;
+	u32 s_sys_blocksize;
+	u32 s_clustersize;
+	int s_block_shift;
+	unsigned long **s_imap;
+	int s_imap_size;
+	struct mutex s_bitmap_lock;
+	kuid_t s_uid;
+	kgid_t s_gid;
+	int s_dmask;
+	int s_fmask;
+};
+
+/* convert a cluster number to a scaled block number */
+static inline sector_t clus_to_blk(struct omfs_sb_info *sbi, sector_t block)
+{
+	return block << sbi->s_block_shift;
+}
+
+static inline struct omfs_sb_info *OMFS_SB(struct super_block *sb)
+{
+	return sb->s_fs_info;
+}
+
+/* bitmap.c */
+extern unsigned long omfs_count_free(struct super_block *sb);
+extern int omfs_allocate_block(struct super_block *sb, u64 block);
+extern int omfs_allocate_range(struct super_block *sb, int min_request,
+			int max_request, u64 *return_block, int *return_size);
+extern int omfs_clear_range(struct super_block *sb, u64 block, int count);
+
+/* dir.c */
+extern const struct file_operations omfs_dir_operations;
+extern const struct inode_operations omfs_dir_inops;
+extern int omfs_make_empty(struct inode *inode, struct super_block *sb);
+extern int omfs_is_bad(struct omfs_sb_info *sbi, struct omfs_header *header,
+			u64 fsblock);
+
+/* file.c */
+extern const struct file_operations omfs_file_operations;
+extern const struct inode_operations omfs_file_inops;
+extern const struct address_space_operations omfs_aops;
+extern void omfs_make_empty_table(struct buffer_head *bh, int offset);
+extern int omfs_shrink_inode(struct inode *inode);
+
+/* inode.c */
+extern struct buffer_head *omfs_bread(struct super_block *sb, sector_t block);
+extern struct inode *omfs_iget(struct super_block *sb, ino_t inode);
+extern struct inode *omfs_new_inode(struct inode *dir, umode_t mode);
+extern int omfs_reserve_block(struct super_block *sb, sector_t block);
+extern int omfs_find_empty_block(struct super_block *sb, int mode, ino_t *ino);
+extern int omfs_sync_inode(struct inode *inode);
+
+#endif