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, 104 insertions, 0 deletions

diff --git a/scripts/dtc/srcpos.h b/scripts/dtc/srcpos.h
new file mode 100644
index 000000000..4d60b50e3
--- /dev/null
+++ b/scripts/dtc/srcpos.h
@@ -0,0 +1,104 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Copyright 2007 Jon Loeliger, Freescale Semiconductor, Inc.
+ */
+
+#ifndef SRCPOS_H
+#define SRCPOS_H
+
+#include <stdio.h>
+#include <stdbool.h>
+#include "util.h"
+
+struct srcfile_state {
+	FILE *f;
+	char *name;
+	char *dir;
+	int lineno, colno;
+	struct srcfile_state *prev;
+};
+
+extern FILE *depfile; /* = NULL */
+extern struct srcfile_state *current_srcfile; /* = NULL */
+
+/**
+ * Open a source file.
+ *
+ * If the source file is a relative pathname, then it is searched for in the
+ * current directory (the directory of the last source file read) and after
+ * that in the search path.
+ *
+ * We work through the search path in order from the first path specified to
+ * the last.
+ *
+ * If the file is not found, then this function does not return, but calls
+ * die().
+ *
+ * @param fname		Filename to search
+ * @param fullnamep	If non-NULL, it is set to the allocated filename of the
+ *			file that was opened. The caller is then responsible
+ *			for freeing the pointer.
+ * @return pointer to opened FILE
+ */
+FILE *srcfile_relative_open(const char *fname, char **fullnamep);
+
+void srcfile_push(const char *fname);
+bool srcfile_pop(void);
+
+/**
+ * Add a new directory to the search path for input files
+ *
+ * The new path is added at the end of the list.
+ *
+ * @param dirname	Directory to add
+ */
+void srcfile_add_search_path(const char *dirname);
+
+struct srcpos {
+    int first_line;
+    int first_column;
+    int last_line;
+    int last_column;
+    struct srcfile_state *file;
+    struct srcpos *next;
+};
+
+#define YYLTYPE struct srcpos
+
+#define YYLLOC_DEFAULT(Current, Rhs, N)						\
+	do {									\
+		if (N) {							\
+			(Current).first_line = YYRHSLOC(Rhs, 1).first_line;	\
+			(Current).first_column = YYRHSLOC(Rhs, 1).first_column;	\
+			(Current).last_line = YYRHSLOC(Rhs, N).last_line;	\
+			(Current).last_column  = YYRHSLOC (Rhs, N).last_column;	\
+			(Current).file = YYRHSLOC(Rhs, N).file;			\
+		} else {							\
+			(Current).first_line = (Current).last_line =		\
+				YYRHSLOC(Rhs, 0).last_line;			\
+			(Current).first_column = (Current).last_column =	\
+				YYRHSLOC(Rhs, 0).last_column;			\
+			(Current).file = YYRHSLOC (Rhs, 0).file;		\
+		}								\
+		(Current).next = NULL;						\
+	} while (0)
+
+
+extern void srcpos_update(struct srcpos *pos, const char *text, int len);
+extern struct srcpos *srcpos_copy(struct srcpos *pos);
+extern struct srcpos *srcpos_extend(struct srcpos *new_srcpos,
+				    struct srcpos *old_srcpos);
+extern void srcpos_free(struct srcpos *pos);
+extern char *srcpos_string(struct srcpos *pos);
+extern char *srcpos_string_first(struct srcpos *pos, int level);
+extern char *srcpos_string_last(struct srcpos *pos, int level);
+
+
+extern void PRINTF(3, 0) srcpos_verror(struct srcpos *pos, const char *prefix,
+					const char *fmt, va_list va);
+extern void PRINTF(3, 4) srcpos_error(struct srcpos *pos, const char *prefix,
+				      const char *fmt, ...);
+
+extern void srcpos_set_line(char *f, int l);
+
+#endif /* SRCPOS_H */