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, 55 insertions, 0 deletions

diff --git a/fs/nilfs2/page.h b/fs/nilfs2/page.h
new file mode 100644
index 000000000..136cd1c14
--- /dev/null
+++ b/fs/nilfs2/page.h
@@ -0,0 +1,55 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Buffer/page management specific to NILFS
+ *
+ * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
+ *
+ * Written by Ryusuke Konishi and Seiji Kihara.
+ */
+
+#ifndef _NILFS_PAGE_H
+#define _NILFS_PAGE_H
+
+#include <linux/buffer_head.h>
+#include "nilfs.h"
+
+/*
+ * Extended buffer state bits
+ */
+enum {
+	BH_NILFS_Allocated = BH_PrivateStart,
+	BH_NILFS_Node,
+	BH_NILFS_Volatile,
+	BH_NILFS_Checked,
+	BH_NILFS_Redirected,
+};
+
+BUFFER_FNS(NILFS_Node, nilfs_node)		/* nilfs node buffers */
+BUFFER_FNS(NILFS_Volatile, nilfs_volatile)
+BUFFER_FNS(NILFS_Checked, nilfs_checked)	/* buffer is verified */
+BUFFER_FNS(NILFS_Redirected, nilfs_redirected)	/* redirected to a copy */
+
+
+void __nilfs_clear_folio_dirty(struct folio *);
+
+struct buffer_head *nilfs_grab_buffer(struct inode *, struct address_space *,
+				      unsigned long, unsigned long);
+void nilfs_forget_buffer(struct buffer_head *);
+void nilfs_copy_buffer(struct buffer_head *, struct buffer_head *);
+bool nilfs_folio_buffers_clean(struct folio *);
+void nilfs_folio_bug(struct folio *);
+
+int nilfs_copy_dirty_pages(struct address_space *, struct address_space *);
+void nilfs_copy_back_pages(struct address_space *, struct address_space *);
+void nilfs_clear_folio_dirty(struct folio *folio);
+void nilfs_clear_dirty_pages(struct address_space *mapping);
+unsigned int nilfs_page_count_clean_buffers(struct folio *folio,
+		unsigned int from, unsigned int to);
+unsigned long nilfs_find_uncommitted_extent(struct inode *inode,
+					    sector_t start_blk,
+					    sector_t *blkoff);
+
+#define NILFS_FOLIO_BUG(folio, m, a...) \
+	do { nilfs_folio_bug(folio); BUG(); } while (0)
+
+#endif /* _NILFS_PAGE_H */