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, 244 insertions, 0 deletions

diff --git a/drivers/input/joystick/cobra.c b/drivers/input/joystick/cobra.c
new file mode 100644
index 000000000..ffa6d49c8
--- /dev/null
+++ b/drivers/input/joystick/cobra.c
@@ -0,0 +1,244 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *  Copyright (c) 1999-2001 Vojtech Pavlik
+ */
+
+/*
+ * Creative Labs Blaster GamePad Cobra driver for Linux
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/gameport.h>
+#include <linux/input.h>
+#include <linux/jiffies.h>
+
+#define DRIVER_DESC	"Creative Labs Blaster GamePad Cobra driver"
+
+MODULE_AUTHOR("Vojtech Pavlik <vojtech@ucw.cz>");
+MODULE_DESCRIPTION(DRIVER_DESC);
+MODULE_LICENSE("GPL");
+
+#define COBRA_MAX_STROBE	45	/* 45 us max wait for first strobe */
+#define COBRA_LENGTH		36
+
+static int cobra_btn[] = { BTN_START, BTN_SELECT, BTN_TL, BTN_TR, BTN_X, BTN_Y, BTN_Z, BTN_A, BTN_B, BTN_C, BTN_TL2, BTN_TR2, 0 };
+
+struct cobra {
+	struct gameport *gameport;
+	struct input_dev *dev[2];
+	int reads;
+	int bads;
+	unsigned char exists;
+	char phys[2][32];
+};
+
+static unsigned char cobra_read_packet(struct gameport *gameport, unsigned int *data)
+{
+	unsigned long flags;
+	unsigned char u, v, w;
+	__u64 buf[2];
+	int r[2], t[2];
+	int i, j, ret;
+
+	int strobe = gameport_time(gameport, COBRA_MAX_STROBE);
+
+	for (i = 0; i < 2; i++) {
+		r[i] = buf[i] = 0;
+		t[i] = COBRA_MAX_STROBE;
+	}
+
+	local_irq_save(flags);
+
+	u = gameport_read(gameport);
+
+	do {
+		t[0]--; t[1]--;
+		v = gameport_read(gameport);
+		for (i = 0, w = u ^ v; i < 2 && w; i++, w >>= 2)
+			if (w & 0x30) {
+				if ((w & 0x30) < 0x30 && r[i] < COBRA_LENGTH && t[i] > 0) {
+					buf[i] |= (__u64)((w >> 5) & 1) << r[i]++;
+					t[i] = strobe;
+					u = v;
+				} else t[i] = 0;
+			}
+	} while (t[0] > 0 || t[1] > 0);
+
+	local_irq_restore(flags);
+
+	ret = 0;
+
+	for (i = 0; i < 2; i++) {
+
+		if (r[i] != COBRA_LENGTH) continue;
+
+		for (j = 0; j < COBRA_LENGTH && (buf[i] & 0x04104107f) ^ 0x041041040; j++)
+			buf[i] = (buf[i] >> 1) | ((__u64)(buf[i] & 1) << (COBRA_LENGTH - 1));
+
+		if (j < COBRA_LENGTH) ret |= (1 << i);
+
+		data[i] = ((buf[i] >>  7) & 0x000001f) | ((buf[i] >>  8) & 0x00003e0)
+			| ((buf[i] >>  9) & 0x0007c00) | ((buf[i] >> 10) & 0x00f8000)
+			| ((buf[i] >> 11) & 0x1f00000);
+
+	}
+
+	return ret;
+}
+
+static void cobra_poll(struct gameport *gameport)
+{
+	struct cobra *cobra = gameport_get_drvdata(gameport);
+	struct input_dev *dev;
+	unsigned int data[2];
+	int i, j, r;
+
+	cobra->reads++;
+
+	if ((r = cobra_read_packet(gameport, data)) != cobra->exists) {
+		cobra->bads++;
+		return;
+	}
+
+	for (i = 0; i < 2; i++)
+		if (cobra->exists & r & (1 << i)) {
+
+			dev = cobra->dev[i];
+
+			input_report_abs(dev, ABS_X, ((data[i] >> 4) & 1) - ((data[i] >> 3) & 1));
+			input_report_abs(dev, ABS_Y, ((data[i] >> 2) & 1) - ((data[i] >> 1) & 1));
+
+			for (j = 0; cobra_btn[j]; j++)
+				input_report_key(dev, cobra_btn[j], data[i] & (0x20 << j));
+
+			input_sync(dev);
+
+		}
+}
+
+static int cobra_open(struct input_dev *dev)
+{
+	struct cobra *cobra = input_get_drvdata(dev);
+
+	gameport_start_polling(cobra->gameport);
+	return 0;
+}
+
+static void cobra_close(struct input_dev *dev)
+{
+	struct cobra *cobra = input_get_drvdata(dev);
+
+	gameport_stop_polling(cobra->gameport);
+}
+
+static int cobra_connect(struct gameport *gameport, struct gameport_driver *drv)
+{
+	struct cobra *cobra;
+	struct input_dev *input_dev;
+	unsigned int data[2];
+	int i, j;
+	int err;
+
+	cobra = kzalloc_obj(*cobra);
+	if (!cobra)
+		return -ENOMEM;
+
+	cobra->gameport = gameport;
+
+	gameport_set_drvdata(gameport, cobra);
+
+	err = gameport_open(gameport, drv, GAMEPORT_MODE_RAW);
+	if (err)
+		goto fail1;
+
+	cobra->exists = cobra_read_packet(gameport, data);
+
+	for (i = 0; i < 2; i++)
+		if ((cobra->exists >> i) & data[i] & 1) {
+			printk(KERN_WARNING "cobra.c: Device %d on %s has the Ext bit set. ID is: %d"
+				" Contact vojtech@ucw.cz\n", i, gameport->phys, (data[i] >> 2) & 7);
+			cobra->exists &= ~(1 << i);
+		}
+
+	if (!cobra->exists) {
+		err = -ENODEV;
+		goto fail2;
+	}
+
+	gameport_set_poll_handler(gameport, cobra_poll);
+	gameport_set_poll_interval(gameport, 20);
+
+	for (i = 0; i < 2; i++) {
+		if (~(cobra->exists >> i) & 1)
+			continue;
+
+		cobra->dev[i] = input_dev = input_allocate_device();
+		if (!input_dev) {
+			err = -ENOMEM;
+			goto fail3;
+		}
+
+		snprintf(cobra->phys[i], sizeof(cobra->phys[i]),
+			 "%s/input%d", gameport->phys, i);
+
+		input_dev->name = "Creative Labs Blaster GamePad Cobra";
+		input_dev->phys = cobra->phys[i];
+		input_dev->id.bustype = BUS_GAMEPORT;
+		input_dev->id.vendor = GAMEPORT_ID_VENDOR_CREATIVE;
+		input_dev->id.product = 0x0008;
+		input_dev->id.version = 0x0100;
+		input_dev->dev.parent = &gameport->dev;
+
+		input_set_drvdata(input_dev, cobra);
+
+		input_dev->open = cobra_open;
+		input_dev->close = cobra_close;
+
+		input_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS);
+		input_set_abs_params(input_dev, ABS_X, -1, 1, 0, 0);
+		input_set_abs_params(input_dev, ABS_Y, -1, 1, 0, 0);
+		for (j = 0; cobra_btn[j]; j++)
+			set_bit(cobra_btn[j], input_dev->keybit);
+
+		err = input_register_device(cobra->dev[i]);
+		if (err)
+			goto fail4;
+	}
+
+	return 0;
+
+ fail4:	input_free_device(cobra->dev[i]);
+ fail3:	while (--i >= 0)
+		if (cobra->dev[i])
+			input_unregister_device(cobra->dev[i]);
+ fail2:	gameport_close(gameport);
+ fail1:	gameport_set_drvdata(gameport, NULL);
+	kfree(cobra);
+	return err;
+}
+
+static void cobra_disconnect(struct gameport *gameport)
+{
+	struct cobra *cobra = gameport_get_drvdata(gameport);
+	int i;
+
+	for (i = 0; i < 2; i++)
+		if ((cobra->exists >> i) & 1)
+			input_unregister_device(cobra->dev[i]);
+	gameport_close(gameport);
+	gameport_set_drvdata(gameport, NULL);
+	kfree(cobra);
+}
+
+static struct gameport_driver cobra_drv = {
+	.driver		= {
+		.name	= "cobra",
+	},
+	.description	= DRIVER_DESC,
+	.connect	= cobra_connect,
+	.disconnect	= cobra_disconnect,
+};
+
+module_gameport_driver(cobra_drv);