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, 43 insertions, 0 deletions

diff --git a/fs/romfs/internal.h b/fs/romfs/internal.h
new file mode 100644
index 000000000..e90df22bd
--- /dev/null
+++ b/fs/romfs/internal.h
@@ -0,0 +1,43 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/* RomFS internal definitions
+ *
+ * Copyright © 2007 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ */
+
+#include <linux/romfs_fs.h>
+
+struct romfs_inode_info {
+	struct inode	vfs_inode;
+	unsigned long	i_metasize;	/* size of non-data area */
+	unsigned long	i_dataoffset;	/* from the start of fs */
+};
+
+static inline size_t romfs_maxsize(struct super_block *sb)
+{
+	return (size_t) (unsigned long) sb->s_fs_info;
+}
+
+static inline struct romfs_inode_info *ROMFS_I(struct inode *inode)
+{
+	return container_of(inode, struct romfs_inode_info, vfs_inode);
+}
+
+/*
+ * mmap-nommu.c
+ */
+#if !defined(CONFIG_MMU) && defined(CONFIG_ROMFS_ON_MTD)
+extern const struct file_operations romfs_ro_fops;
+#else
+#define romfs_ro_fops	generic_ro_fops
+#endif
+
+/*
+ * storage.c
+ */
+extern int romfs_dev_read(struct super_block *sb, unsigned long pos,
+			  void *buf, size_t buflen);
+extern ssize_t romfs_dev_strnlen(struct super_block *sb,
+				 unsigned long pos, size_t maxlen);
+extern int romfs_dev_strcmp(struct super_block *sb, unsigned long pos,
+			    const char *str, size_t size);