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, 91 insertions, 0 deletions

diff --git a/drivers/input/serio/i8042.h b/drivers/input/serio/i8042.h
new file mode 100644
index 000000000..5f61672d5
--- /dev/null
+++ b/drivers/input/serio/i8042.h
@@ -0,0 +1,91 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+#ifndef _I8042_H
+#define _I8042_H
+
+
+/*
+ *  Copyright (c) 1999-2002 Vojtech Pavlik
+ */
+
+/*
+ * Arch-dependent inline functions and defines.
+ */
+
+#if defined(CONFIG_MACH_JAZZ)
+#include "i8042-jazzio.h"
+#elif defined(CONFIG_SGI_HAS_I8042)
+#include "i8042-ip22io.h"
+#elif defined(CONFIG_SNI_RM)
+#include "i8042-snirm.h"
+#elif defined(CONFIG_SPARC)
+#include "i8042-sparcio.h"
+#elif defined(CONFIG_X86) || defined(CONFIG_LOONGARCH)
+#include "i8042-acpipnpio.h"
+#else
+#include "i8042-io.h"
+#endif
+
+/*
+ * This is in 50us units, the time we wait for the i8042 to react. This
+ * has to be long enough for the i8042 itself to timeout on sending a byte
+ * to a non-existent mouse.
+ */
+
+#define I8042_CTL_TIMEOUT	10000
+
+/*
+ * Return codes.
+ */
+
+#define I8042_RET_CTL_TEST	0x55
+
+/*
+ * Expected maximum internal i8042 buffer size. This is used for flushing
+ * the i8042 buffers.
+ */
+
+#define I8042_BUFFER_SIZE	16
+
+/*
+ * Number of AUX ports on controllers supporting active multiplexing
+ * specification
+ */
+
+#define I8042_NUM_MUX_PORTS	4
+
+/*
+ * Debug.
+ */
+
+#ifdef DEBUG
+static unsigned long i8042_start_time;
+#define dbg_init() do { i8042_start_time = jiffies; } while (0)
+#define dbg(format, arg...)							\
+	do {									\
+		if (i8042_debug)						\
+			printk(KERN_DEBUG KBUILD_MODNAME ": [%d] " format,	\
+			       (int) (jiffies - i8042_start_time), ##arg);	\
+	} while (0)
+
+#define filter_dbg(filter, data, format, args...)		\
+	do {							\
+		if (!i8042_debug)				\
+			break;					\
+								\
+		if (!filter || i8042_unmask_kbd_data)		\
+			dbg("%02x " format, data, ##args);	\
+		else						\
+			dbg("** " format, ##args);		\
+	} while (0)
+#else
+#define dbg_init() do { } while (0)
+#define dbg(format, arg...)							\
+	do {									\
+		if (0)								\
+			printk(KERN_DEBUG pr_fmt(format), ##arg);		\
+	} while (0)
+
+#define filter_dbg(filter, data, format, args...) do { } while (0)
+#endif
+
+#endif /* _I8042_H */