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, 23 insertions, 0 deletions

diff --git a/fs/coda/coda_cache.h b/fs/coda/coda_cache.h
new file mode 100644
index 000000000..c9f7a77c0
--- /dev/null
+++ b/fs/coda/coda_cache.h
@@ -0,0 +1,23 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* Coda filesystem -- Linux Minicache
+ *
+ * Copyright (C) 1989 - 1997 Carnegie Mellon University
+ *
+ * Carnegie Mellon University encourages users of this software to
+ * contribute improvements to the Coda project. Contact Peter Braam
+ * <coda@cs.cmu.edu>
+ */
+
+#ifndef _CFSNC_HEADER_
+#define _CFSNC_HEADER_
+
+/* credential cache */
+void coda_cache_enter(struct inode *inode, int mask);
+void coda_cache_clear_inode(struct inode *);
+void coda_cache_clear_all(struct super_block *sb);
+int coda_cache_check(struct inode *inode, int mask);
+
+/* for downcalls and attributes and lookups */
+void coda_flag_inode_children(struct inode *inode, int flag);
+
+#endif /* _CFSNC_HEADER_ */