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, 82 insertions, 0 deletions

diff --git a/fs/gfs2/dir.h b/fs/gfs2/dir.h
new file mode 100644
index 000000000..25a857c78
--- /dev/null
+++ b/fs/gfs2/dir.h
@@ -0,0 +1,82 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) Sistina Software, Inc.  1997-2003 All rights reserved.
+ * Copyright (C) 2004-2006 Red Hat, Inc.  All rights reserved.
+ */
+
+#ifndef __DIR_DOT_H__
+#define __DIR_DOT_H__
+
+#include <linux/dcache.h>
+#include <linux/crc32.h>
+
+struct inode;
+struct gfs2_inode;
+struct gfs2_inum;
+struct buffer_head;
+struct gfs2_dirent;
+
+struct gfs2_diradd {
+	unsigned nr_blocks;
+	struct gfs2_dirent *dent;
+	struct buffer_head *bh;
+	int save_loc;
+};
+
+struct inode *gfs2_dir_search(struct inode *dir,
+			      const struct qstr *filename,
+			      bool fail_on_exist);
+int gfs2_dir_check(struct inode *dir, const struct qstr *filename,
+		   const struct gfs2_inode *ip);
+int gfs2_dir_add(struct inode *inode, const struct qstr *filename,
+		 const struct gfs2_inode *ip, struct gfs2_diradd *da);
+static inline void gfs2_dir_no_add(struct gfs2_diradd *da)
+{
+	brelse(da->bh);
+	da->bh = NULL;
+}
+int gfs2_dir_del(struct gfs2_inode *dip, const struct dentry *dentry);
+int gfs2_dir_read(struct inode *inode, struct dir_context *ctx,
+		  struct file_ra_state *f_ra);
+int gfs2_dir_mvino(struct gfs2_inode *dip, const struct qstr *filename,
+		   const struct gfs2_inode *nip, unsigned int new_type);
+
+int gfs2_dir_exhash_dealloc(struct gfs2_inode *dip);
+
+int gfs2_diradd_alloc_required(struct inode *dir,
+			       const struct qstr *filename,
+			       struct gfs2_diradd *da);
+int gfs2_dir_get_new_buffer(struct gfs2_inode *ip, u64 block,
+			    struct buffer_head **bhp);
+void gfs2_dir_hash_inval(struct gfs2_inode *ip);
+
+static inline u32 gfs2_disk_hash(const char *data, int len)
+{
+        return crc32_le((u32)~0, data, len) ^ (u32)~0;
+}
+
+
+static inline void gfs2_str2qstr(struct qstr *name, const char *fname)
+{
+	name->name = fname;
+	name->len = strlen(fname);
+	name->hash = gfs2_disk_hash(name->name, name->len);
+}
+
+/* N.B. This probably ought to take inum & type as args as well */
+static inline void gfs2_qstr2dirent(const struct qstr *name, u16 reclen, struct gfs2_dirent *dent)
+{
+	dent->de_inum.no_addr = cpu_to_be64(0);
+	dent->de_inum.no_formal_ino = cpu_to_be64(0);
+	dent->de_hash = cpu_to_be32(name->hash);
+	dent->de_rec_len = cpu_to_be16(reclen);
+	dent->de_name_len = cpu_to_be16(name->len);
+	dent->de_type = cpu_to_be16(0);
+	memset(dent->__pad, 0, sizeof(dent->__pad));
+	memcpy(dent + 1, name->name, name->len);
+}
+
+extern struct qstr gfs2_qdot;
+extern struct qstr gfs2_qdotdot;
+
+#endif /* __DIR_DOT_H__ */