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, 38 insertions, 0 deletions

diff --git a/lib/fonts/font.h b/lib/fonts/font.h
new file mode 100644
index 000000000..4f1adf0b6
--- /dev/null
+++ b/lib/fonts/font.h
@@ -0,0 +1,38 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef _LIB_FONTS_FONT_H
+#define _LIB_FONTS_FONT_H
+
+#include <linux/font.h>
+
+/*
+ * Font data
+ */
+
+#define FONT_EXTRA_WORDS 4
+
+struct font_data {
+	unsigned int extra[FONT_EXTRA_WORDS];
+	unsigned char data[];
+} __packed;
+
+/*
+ * Built-in fonts
+ */
+
+#define VGA8x8_IDX	0
+#define VGA8x16_IDX	1
+#define PEARL8x8_IDX	2
+#define VGA6x11_IDX	3
+#define FONT7x14_IDX	4
+#define	FONT10x18_IDX	5
+#define SUN8x16_IDX	6
+#define SUN12x22_IDX	7
+#define ACORN8x8_IDX	8
+#define	MINI4x6_IDX	9
+#define FONT6x10_IDX	10
+#define TER16x32_IDX	11
+#define FONT6x8_IDX	12
+#define TER10x18_IDX	13
+
+#endif