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, 29 insertions, 0 deletions

diff --git a/fs/ntfs/lib/lib.h b/fs/ntfs/lib/lib.h
new file mode 100644
index 000000000..a684d600f
--- /dev/null
+++ b/fs/ntfs/lib/lib.h
@@ -0,0 +1,29 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * lib.h - Public declarations for the LZX and XPRESS decompressors.
+ *
+ * Adapted for the linux kernel.  These are the low-level decompressor
+ * allocations; WOF (system-compressed) access goes through the
+ * ntfs_codec_ops interface declared in "../ntfs_codec.h".
+ */
+
+#ifndef _LINUX_NTFS_LIB_LIB_H
+#define _LINUX_NTFS_LIB_LIB_H
+
+#include <linux/types.h>
+
+/* globals from xpress_decompress.c */
+struct xpress_decompressor *xpress_allocate_decompressor(void);
+void xpress_free_decompressor(struct xpress_decompressor *d);
+int xpress_decompress(struct xpress_decompressor *d,
+		      const void *compressed_data, size_t compressed_size,
+		      void *uncompressed_data, size_t uncompressed_size);
+
+/* globals from lzx_decompress.c */
+struct lzx_decompressor *lzx_allocate_decompressor(void);
+void lzx_free_decompressor(struct lzx_decompressor *d);
+int lzx_decompress(struct lzx_decompressor *d, const void *compressed_data,
+		   size_t compressed_size, void *uncompressed_data,
+		   size_t uncompressed_size);
+
+#endif /* _LINUX_NTFS_LIB_LIB_H */