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, 297 insertions, 0 deletions

diff --git a/drivers/input/joystick/walkera0701.c b/drivers/input/joystick/walkera0701.c
new file mode 100644
index 000000000..15370fb82
--- /dev/null
+++ b/drivers/input/joystick/walkera0701.c
@@ -0,0 +1,297 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *  Parallel port to Walkera WK-0701 TX joystick
+ *
+ *  Copyright (c) 2008 Peter Popovec
+ *
+ *  More about driver:  <file:Documentation/input/devices/walkera0701.rst>
+ */
+
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#define RESERVE 20000
+#define SYNC_PULSE 1306000
+#define BIN0_PULSE 288000
+#define BIN1_PULSE 438000
+
+#define ANALOG_MIN_PULSE 318000
+#define ANALOG_MAX_PULSE 878000
+#define ANALOG_DELTA 80000
+
+#define BIN_SAMPLE ((BIN0_PULSE + BIN1_PULSE) / 2)
+
+#define NO_SYNC 25
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/parport.h>
+#include <linux/input.h>
+#include <linux/hrtimer.h>
+
+MODULE_AUTHOR("Peter Popovec <popovec@fei.tuke.sk>");
+MODULE_DESCRIPTION("Walkera WK-0701 TX as joystick");
+MODULE_LICENSE("GPL");
+
+static unsigned int walkera0701_pp_no;
+module_param_named(port, walkera0701_pp_no, int, 0);
+MODULE_PARM_DESC(port,
+		 "Parallel port adapter for Walkera WK-0701 TX (default is 0)");
+
+/*
+ * For now, only one device is supported, if somebody need more devices, code
+ * can be expanded, one struct walkera_dev per device must be allocated and
+ * set up by walkera0701_connect (release of device by walkera0701_disconnect)
+ */
+
+struct walkera_dev {
+	unsigned char buf[25];
+	u64 irq_time, irq_lasttime;
+	int counter;
+	int ack;
+
+	struct input_dev *input_dev;
+	struct hrtimer timer;
+
+	struct parport *parport;
+	struct pardevice *pardevice;
+};
+
+static struct walkera_dev w_dev;
+
+static inline void walkera0701_parse_frame(struct walkera_dev *w)
+{
+	int i;
+	int val1, val2, val3, val4, val5, val6, val7, val8;
+	int magic, magic_bit;
+	int crc1, crc2;
+
+	for (crc1 = crc2 = i = 0; i < 10; i++) {
+		crc1 += w->buf[i] & 7;
+		crc2 += (w->buf[i] & 8) >> 3;
+	}
+	if ((w->buf[10] & 7) != (crc1 & 7))
+		return;
+	if (((w->buf[10] & 8) >> 3) != (((crc1 >> 3) + crc2) & 1))
+		return;
+	for (crc1 = crc2 = 0, i = 11; i < 23; i++) {
+		crc1 += w->buf[i] & 7;
+		crc2 += (w->buf[i] & 8) >> 3;
+	}
+	if ((w->buf[23] & 7) != (crc1 & 7))
+		return;
+	if (((w->buf[23] & 8) >> 3) != (((crc1 >> 3) + crc2) & 1))
+		return;
+	val1 = ((w->buf[0] & 7) * 256 + w->buf[1] * 16 + w->buf[2]) >> 2;
+	val1 *= ((w->buf[0] >> 2) & 2) - 1;	/* sign */
+	val2 = (w->buf[2] & 1) << 8 | (w->buf[3] << 4) | w->buf[4];
+	val2 *= (w->buf[2] & 2) - 1;	/* sign */
+	val3 = ((w->buf[5] & 7) * 256 + w->buf[6] * 16 + w->buf[7]) >> 2;
+	val3 *= ((w->buf[5] >> 2) & 2) - 1;	/* sign */
+	val4 = (w->buf[7] & 1) << 8 | (w->buf[8] << 4) | w->buf[9];
+	val4 *= (w->buf[7] & 2) - 1;	/* sign */
+	val5 = ((w->buf[11] & 7) * 256 + w->buf[12] * 16 + w->buf[13]) >> 2;
+	val5 *= ((w->buf[11] >> 2) & 2) - 1;	/* sign */
+	val6 = (w->buf[13] & 1) << 8 | (w->buf[14] << 4) | w->buf[15];
+	val6 *= (w->buf[13] & 2) - 1;	/* sign */
+	val7 = ((w->buf[16] & 7) * 256 + w->buf[17] * 16 + w->buf[18]) >> 2;
+	val7 *= ((w->buf[16] >> 2) & 2) - 1;	/*sign */
+	val8 = (w->buf[18] & 1) << 8 | (w->buf[19] << 4) | w->buf[20];
+	val8 *= (w->buf[18] & 2) - 1;	/*sign */
+
+	magic = (w->buf[21] << 4) | w->buf[22];
+	magic_bit = (w->buf[24] & 8) >> 3;
+	pr_debug("%4d %4d %4d %4d  %4d %4d %4d %4d (magic %2x %d)\n",
+		 val1, val2, val3, val4, val5, val6, val7, val8,
+		 magic, magic_bit);
+
+	input_report_abs(w->input_dev, ABS_X, val2);
+	input_report_abs(w->input_dev, ABS_Y, val1);
+	input_report_abs(w->input_dev, ABS_Z, val6);
+	input_report_abs(w->input_dev, ABS_THROTTLE, val3);
+	input_report_abs(w->input_dev, ABS_RUDDER, val4);
+	input_report_abs(w->input_dev, ABS_MISC, val7);
+	input_report_key(w->input_dev, BTN_GEAR_DOWN, val5 > 0);
+}
+
+static inline int read_ack(struct pardevice *p)
+{
+	return parport_read_status(p->port) & 0x40;
+}
+
+/* falling edge, prepare to BIN value calculation */
+static void walkera0701_irq_handler(void *handler_data)
+{
+	u64 pulse_time;
+	struct walkera_dev *w = handler_data;
+
+	w->irq_time = ktime_to_ns(ktime_get());
+	pulse_time = w->irq_time - w->irq_lasttime;
+	w->irq_lasttime = w->irq_time;
+
+	/* cancel timer, if in handler or active do resync */
+	if (unlikely(0 != hrtimer_try_to_cancel(&w->timer))) {
+		w->counter = NO_SYNC;
+		return;
+	}
+
+	if (w->counter < NO_SYNC) {
+		if (w->ack) {
+			pulse_time -= BIN1_PULSE;
+			w->buf[w->counter] = 8;
+		} else {
+			pulse_time -= BIN0_PULSE;
+			w->buf[w->counter] = 0;
+		}
+		if (w->counter == 24) {	/* full frame */
+			walkera0701_parse_frame(w);
+			w->counter = NO_SYNC;
+			if (abs(pulse_time - SYNC_PULSE) < RESERVE)	/* new frame sync */
+				w->counter = 0;
+		} else {
+			if ((pulse_time > (ANALOG_MIN_PULSE - RESERVE)
+			     && (pulse_time < (ANALOG_MAX_PULSE + RESERVE)))) {
+				pulse_time -= (ANALOG_MIN_PULSE - RESERVE);
+				pulse_time = (u32) pulse_time / ANALOG_DELTA;	/* overtiping is safe, pulsetime < s32.. */
+				w->buf[w->counter++] |= (pulse_time & 7);
+			} else
+				w->counter = NO_SYNC;
+		}
+	} else if (abs(pulse_time - SYNC_PULSE - BIN0_PULSE) <
+				RESERVE + BIN1_PULSE - BIN0_PULSE)	/* frame sync .. */
+		w->counter = 0;
+
+	hrtimer_start(&w->timer, BIN_SAMPLE, HRTIMER_MODE_REL);
+}
+
+static enum hrtimer_restart timer_handler(struct hrtimer
+					  *handle)
+{
+	struct walkera_dev *w;
+
+	w = container_of(handle, struct walkera_dev, timer);
+	w->ack = read_ack(w->pardevice);
+
+	return HRTIMER_NORESTART;
+}
+
+static int walkera0701_open(struct input_dev *dev)
+{
+	struct walkera_dev *w = input_get_drvdata(dev);
+
+	if (parport_claim(w->pardevice))
+		return -EBUSY;
+
+	parport_enable_irq(w->parport);
+	return 0;
+}
+
+static void walkera0701_close(struct input_dev *dev)
+{
+	struct walkera_dev *w = input_get_drvdata(dev);
+
+	parport_disable_irq(w->parport);
+	hrtimer_cancel(&w->timer);
+
+	parport_release(w->pardevice);
+}
+
+static void walkera0701_attach(struct parport *pp)
+{
+	struct pardev_cb walkera0701_parport_cb;
+	struct walkera_dev *w = &w_dev;
+
+	if (pp->number != walkera0701_pp_no) {
+		pr_debug("Not using parport%d.\n", pp->number);
+		return;
+	}
+
+	if (pp->irq == -1) {
+		pr_err("parport %d does not have interrupt assigned\n",
+			pp->number);
+		return;
+	}
+
+	w->parport = pp;
+
+	memset(&walkera0701_parport_cb, 0, sizeof(walkera0701_parport_cb));
+	walkera0701_parport_cb.flags = PARPORT_FLAG_EXCL;
+	walkera0701_parport_cb.irq_func = walkera0701_irq_handler;
+	walkera0701_parport_cb.private = w;
+
+	w->pardevice = parport_register_dev_model(pp, "walkera0701",
+						  &walkera0701_parport_cb, 0);
+
+	if (!w->pardevice) {
+		pr_err("failed to register parport device\n");
+		return;
+	}
+
+	if (parport_negotiate(w->pardevice->port, IEEE1284_MODE_COMPAT)) {
+		pr_err("failed to negotiate parport mode\n");
+		goto err_unregister_device;
+	}
+
+	hrtimer_setup(&w->timer, timer_handler, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+
+	w->input_dev = input_allocate_device();
+	if (!w->input_dev) {
+		pr_err("failed to allocate input device\n");
+		goto err_unregister_device;
+	}
+
+	input_set_drvdata(w->input_dev, w);
+	w->input_dev->name = "Walkera WK-0701 TX";
+	w->input_dev->phys = w->parport->name;
+	w->input_dev->id.bustype = BUS_PARPORT;
+
+	/* TODO what id vendor/product/version ? */
+	w->input_dev->id.vendor = 0x0001;
+	w->input_dev->id.product = 0x0001;
+	w->input_dev->id.version = 0x0100;
+	w->input_dev->dev.parent = w->parport->dev;
+	w->input_dev->open = walkera0701_open;
+	w->input_dev->close = walkera0701_close;
+
+	w->input_dev->evbit[0] = BIT(EV_ABS) | BIT_MASK(EV_KEY);
+	w->input_dev->keybit[BIT_WORD(BTN_GEAR_DOWN)] = BIT_MASK(BTN_GEAR_DOWN);
+
+	input_set_abs_params(w->input_dev, ABS_X, -512, 512, 0, 0);
+	input_set_abs_params(w->input_dev, ABS_Y, -512, 512, 0, 0);
+	input_set_abs_params(w->input_dev, ABS_Z, -512, 512, 0, 0);
+	input_set_abs_params(w->input_dev, ABS_THROTTLE, -512, 512, 0, 0);
+	input_set_abs_params(w->input_dev, ABS_RUDDER, -512, 512, 0, 0);
+	input_set_abs_params(w->input_dev, ABS_MISC, -512, 512, 0, 0);
+
+	if (input_register_device(w->input_dev)) {
+		pr_err("failed to register input device\n");
+		goto err_free_input_dev;
+	}
+
+	return;
+
+err_free_input_dev:
+	input_free_device(w->input_dev);
+err_unregister_device:
+	parport_unregister_device(w->pardevice);
+}
+
+static void walkera0701_detach(struct parport *port)
+{
+	struct walkera_dev *w = &w_dev;
+
+	if (!w->pardevice || w->parport->number != port->number)
+		return;
+
+	input_unregister_device(w->input_dev);
+	parport_unregister_device(w->pardevice);
+	w->parport = NULL;
+}
+
+static struct parport_driver walkera0701_parport_driver = {
+	.name = "walkera0701",
+	.match_port = walkera0701_attach,
+	.detach = walkera0701_detach,
+};
+
+module_parport_driver(walkera0701_parport_driver);