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, 153 insertions, 0 deletions

diff --git a/drivers/input/mouse/atarimouse.c b/drivers/input/mouse/atarimouse.c
new file mode 100644
index 000000000..b1219cc4d
--- /dev/null
+++ b/drivers/input/mouse/atarimouse.c
@@ -0,0 +1,153 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *  Atari mouse driver for Linux/m68k
+ *
+ *  Copyright (c) 2005 Michael Schmitz
+ *
+ *  Based on:
+ *  Amiga mouse driver for Linux/m68k
+ *
+ *  Copyright (c) 2000-2002 Vojtech Pavlik
+ */
+/*
+ * The low level init and interrupt stuff is handled in arch/mm68k/atari/atakeyb.c
+ * (the keyboard ACIA also handles the mouse and joystick data, and the keyboard
+ * interrupt is shared with the MIDI ACIA so MIDI data also get handled there).
+ * This driver only deals with handing key events off to the input layer.
+ *
+ * Largely based on the old:
+ *
+ * Atari Mouse Driver for Linux
+ * by Robert de Vries (robert@and.nl) 19Jul93
+ *
+ * 16 Nov 1994 Andreas Schwab
+ * Compatibility with busmouse
+ * Support for three button mouse (shamelessly stolen from MiNT)
+ * third button wired to one of the joystick directions on joystick 1
+ *
+ * 1996/02/11 Andreas Schwab
+ * Module support
+ * Allow multiple open's
+ *
+ * Converted to use new generic busmouse code.  5 Apr 1998
+ *   Russell King <rmk@arm.uk.linux.org>
+ */
+
+
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/input.h>
+#include <linux/interrupt.h>
+
+#include <asm/irq.h>
+#include <asm/setup.h>
+#include <linux/uaccess.h>
+#include <asm/atarihw.h>
+#include <asm/atarikb.h>
+#include <asm/atariints.h>
+
+MODULE_AUTHOR("Michael Schmitz <schmitz@biophys.uni-duesseldorf.de>");
+MODULE_DESCRIPTION("Atari mouse driver");
+MODULE_LICENSE("GPL");
+
+static int mouse_threshold[2] = {2, 2};
+module_param_array(mouse_threshold, int, NULL, 0);
+
+#ifdef FIXED_ATARI_JOYSTICK
+extern int atari_mouse_buttons;
+#endif
+
+static struct input_dev *atamouse_dev;
+
+static void atamouse_interrupt(char *buf)
+{
+	int buttons, dx, dy;
+
+	buttons = (buf[0] & 1) | ((buf[0] & 2) << 1);
+#ifdef FIXED_ATARI_JOYSTICK
+	buttons |= atari_mouse_buttons & 2;
+	atari_mouse_buttons = buttons;
+#endif
+
+	/* only relative events get here */
+	dx = buf[1];
+	dy = buf[2];
+
+	input_report_rel(atamouse_dev, REL_X, dx);
+	input_report_rel(atamouse_dev, REL_Y, dy);
+
+	input_report_key(atamouse_dev, BTN_LEFT,   buttons & 0x4);
+	input_report_key(atamouse_dev, BTN_MIDDLE, buttons & 0x2);
+	input_report_key(atamouse_dev, BTN_RIGHT,  buttons & 0x1);
+
+	input_sync(atamouse_dev);
+
+	return;
+}
+
+static int atamouse_open(struct input_dev *dev)
+{
+#ifdef FIXED_ATARI_JOYSTICK
+	atari_mouse_buttons = 0;
+#endif
+	ikbd_mouse_y0_top();
+	ikbd_mouse_thresh(mouse_threshold[0], mouse_threshold[1]);
+	ikbd_mouse_rel_pos();
+	atari_input_mouse_interrupt_hook = atamouse_interrupt;
+
+	return 0;
+}
+
+static void atamouse_close(struct input_dev *dev)
+{
+	ikbd_mouse_disable();
+	atari_input_mouse_interrupt_hook = NULL;
+}
+
+static int __init atamouse_init(void)
+{
+	int error;
+
+	if (!MACH_IS_ATARI || !ATARIHW_PRESENT(ST_MFP))
+		return -ENODEV;
+
+	error = atari_keyb_init();
+	if (error)
+		return error;
+
+	atamouse_dev = input_allocate_device();
+	if (!atamouse_dev)
+		return -ENOMEM;
+
+	atamouse_dev->name = "Atari mouse";
+	atamouse_dev->phys = "atamouse/input0";
+	atamouse_dev->id.bustype = BUS_HOST;
+	atamouse_dev->id.vendor = 0x0001;
+	atamouse_dev->id.product = 0x0002;
+	atamouse_dev->id.version = 0x0100;
+
+	atamouse_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_REL);
+	atamouse_dev->relbit[0] = BIT_MASK(REL_X) | BIT_MASK(REL_Y);
+	atamouse_dev->keybit[BIT_WORD(BTN_LEFT)] = BIT_MASK(BTN_LEFT) |
+		BIT_MASK(BTN_MIDDLE) | BIT_MASK(BTN_RIGHT);
+
+	atamouse_dev->open = atamouse_open;
+	atamouse_dev->close = atamouse_close;
+
+	error = input_register_device(atamouse_dev);
+	if (error) {
+		input_free_device(atamouse_dev);
+		return error;
+	}
+
+	return 0;
+}
+
+static void __exit atamouse_exit(void)
+{
+	input_unregister_device(atamouse_dev);
+}
+
+module_init(atamouse_init);
+module_exit(atamouse_exit);