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, 304 insertions, 0 deletions

diff --git a/drivers/input/keyboard/omap-keypad.c b/drivers/input/keyboard/omap-keypad.c
new file mode 100644
index 000000000..589f51d43
--- /dev/null
+++ b/drivers/input/keyboard/omap-keypad.c
@@ -0,0 +1,304 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * linux/drivers/input/keyboard/omap-keypad.c
+ *
+ * OMAP Keypad Driver
+ *
+ * Copyright (C) 2003 Nokia Corporation
+ * Written by Timo Teräs <ext-timo.teras@nokia.com>
+ *
+ * Added support for H2 & H3 Keypad
+ * Copyright (C) 2004 Texas Instruments
+ */
+
+#include <linux/module.h>
+#include <linux/interrupt.h>
+#include <linux/types.h>
+#include <linux/input.h>
+#include <linux/kernel.h>
+#include <linux/delay.h>
+#include <linux/platform_device.h>
+#include <linux/mutex.h>
+#include <linux/errno.h>
+#include <linux/slab.h>
+#include <linux/platform_data/gpio-omap.h>
+#include <linux/platform_data/keypad-omap.h>
+#include <linux/soc/ti/omap1-io.h>
+
+#undef NEW_BOARD_LEARNING_MODE
+
+static void omap_kp_tasklet(unsigned long);
+static void omap_kp_timer(struct timer_list *);
+
+static unsigned char keypad_state[8];
+static DEFINE_MUTEX(kp_enable_mutex);
+static int kp_enable = 1;
+static int kp_cur_group = -1;
+
+struct omap_kp {
+	struct input_dev *input;
+	struct timer_list timer;
+	int irq;
+	unsigned int rows;
+	unsigned int cols;
+	unsigned long delay;
+	unsigned int debounce;
+	unsigned short keymap[];
+};
+
+static DECLARE_TASKLET_DISABLED_OLD(kp_tasklet, omap_kp_tasklet);
+
+static irqreturn_t omap_kp_interrupt(int irq, void *dev_id)
+{
+	/* disable keyboard interrupt and schedule for handling */
+	omap_writew(1, OMAP1_MPUIO_BASE + OMAP_MPUIO_KBD_MASKIT);
+
+	tasklet_schedule(&kp_tasklet);
+
+	return IRQ_HANDLED;
+}
+
+static void omap_kp_timer(struct timer_list *unused)
+{
+	tasklet_schedule(&kp_tasklet);
+}
+
+static void omap_kp_scan_keypad(struct omap_kp *omap_kp, unsigned char *state)
+{
+	int col = 0;
+
+	/* disable keyboard interrupt and schedule for handling */
+	omap_writew(1, OMAP1_MPUIO_BASE + OMAP_MPUIO_KBD_MASKIT);
+
+	/* read the keypad status */
+	omap_writew(0xff, OMAP1_MPUIO_BASE + OMAP_MPUIO_KBC);
+	for (col = 0; col < omap_kp->cols; col++) {
+		omap_writew(~(1 << col) & 0xff,
+			    OMAP1_MPUIO_BASE + OMAP_MPUIO_KBC);
+
+		udelay(omap_kp->delay);
+
+		state[col] = ~omap_readw(OMAP1_MPUIO_BASE +
+					 OMAP_MPUIO_KBR_LATCH) & 0xff;
+	}
+	omap_writew(0x00, OMAP1_MPUIO_BASE + OMAP_MPUIO_KBC);
+	udelay(2);
+}
+
+static void omap_kp_tasklet(unsigned long data)
+{
+	struct omap_kp *omap_kp_data = (struct omap_kp *) data;
+	unsigned short *keycodes = omap_kp_data->input->keycode;
+	unsigned int row_shift = get_count_order(omap_kp_data->cols);
+	unsigned char new_state[8], changed, key_down = 0;
+	int col, row;
+
+	/* check for any changes */
+	omap_kp_scan_keypad(omap_kp_data, new_state);
+
+	/* check for changes and print those */
+	for (col = 0; col < omap_kp_data->cols; col++) {
+		changed = new_state[col] ^ keypad_state[col];
+		key_down |= new_state[col];
+		if (changed == 0)
+			continue;
+
+		for (row = 0; row < omap_kp_data->rows; row++) {
+			int key;
+			if (!(changed & (1 << row)))
+				continue;
+#ifdef NEW_BOARD_LEARNING_MODE
+			printk(KERN_INFO "omap-keypad: key %d-%d %s\n", col,
+			       row, (new_state[col] & (1 << row)) ?
+			       "pressed" : "released");
+#else
+			key = keycodes[MATRIX_SCAN_CODE(row, col, row_shift)];
+
+			if (!(kp_cur_group == (key & GROUP_MASK) ||
+			      kp_cur_group == -1))
+				continue;
+
+			kp_cur_group = key & GROUP_MASK;
+			input_report_key(omap_kp_data->input, key & ~GROUP_MASK,
+					 new_state[col] & (1 << row));
+#endif
+		}
+	}
+	input_sync(omap_kp_data->input);
+	memcpy(keypad_state, new_state, sizeof(keypad_state));
+
+	if (key_down) {
+		/* some key is pressed - keep irq disabled and use timer
+		 * to poll the keypad */
+		mod_timer(&omap_kp_data->timer, jiffies + HZ / 20);
+	} else {
+		/* enable interrupts */
+		omap_writew(0, OMAP1_MPUIO_BASE + OMAP_MPUIO_KBD_MASKIT);
+		kp_cur_group = -1;
+	}
+}
+
+static ssize_t omap_kp_enable_show(struct device *dev,
+				   struct device_attribute *attr, char *buf)
+{
+	return sprintf(buf, "%u\n", kp_enable);
+}
+
+static ssize_t omap_kp_enable_store(struct device *dev, struct device_attribute *attr,
+				    const char *buf, size_t count)
+{
+	struct omap_kp *omap_kp = dev_get_drvdata(dev);
+	int state;
+
+	if (sscanf(buf, "%u", &state) != 1)
+		return -EINVAL;
+
+	if ((state != 1) && (state != 0))
+		return -EINVAL;
+
+	scoped_guard(mutex, &kp_enable_mutex) {
+		if (state != kp_enable) {
+			if (state)
+				enable_irq(omap_kp->irq);
+			else
+				disable_irq(omap_kp->irq);
+			kp_enable = state;
+		}
+	}
+
+	return strnlen(buf, count);
+}
+
+static DEVICE_ATTR(enable, S_IRUGO | S_IWUSR, omap_kp_enable_show, omap_kp_enable_store);
+
+static struct attribute *omap_kp_attrs[] = {
+	&dev_attr_enable.attr,
+	NULL
+};
+ATTRIBUTE_GROUPS(omap_kp);
+
+static int omap_kp_probe(struct platform_device *pdev)
+{
+	struct omap_kp *omap_kp;
+	struct input_dev *input_dev;
+	struct omap_kp_platform_data *pdata = dev_get_platdata(&pdev->dev);
+	int ret;
+	unsigned int row_shift, keycodemax;
+
+	if (!pdata->rows || !pdata->cols || !pdata->keymap_data) {
+		printk(KERN_ERR "No rows, cols or keymap_data from pdata\n");
+		return -EINVAL;
+	}
+
+	row_shift = get_count_order(pdata->cols);
+	keycodemax = pdata->rows << row_shift;
+
+	omap_kp = kzalloc_flex(*omap_kp, keymap, keycodemax);
+	input_dev = input_allocate_device();
+	if (!omap_kp || !input_dev) {
+		kfree(omap_kp);
+		input_free_device(input_dev);
+		return -ENOMEM;
+	}
+
+	platform_set_drvdata(pdev, omap_kp);
+
+	omap_kp->input = input_dev;
+
+	/* Disable the interrupt for the MPUIO keyboard */
+	omap_writew(1, OMAP1_MPUIO_BASE + OMAP_MPUIO_KBD_MASKIT);
+
+	if (pdata->delay)
+		omap_kp->delay = pdata->delay;
+
+	omap_kp->rows = pdata->rows;
+	omap_kp->cols = pdata->cols;
+
+	timer_setup(&omap_kp->timer, omap_kp_timer, 0);
+
+	/* get the irq and init timer*/
+	kp_tasklet.data = (unsigned long) omap_kp;
+	tasklet_enable(&kp_tasklet);
+
+	/* setup input device */
+	input_dev->name = "omap-keypad";
+	input_dev->phys = "omap-keypad/input0";
+	input_dev->dev.parent = &pdev->dev;
+
+	input_dev->id.bustype = BUS_HOST;
+	input_dev->id.vendor = 0x0001;
+	input_dev->id.product = 0x0001;
+	input_dev->id.version = 0x0100;
+
+	if (pdata->rep)
+		__set_bit(EV_REP, input_dev->evbit);
+
+	ret = matrix_keypad_build_keymap(pdata->keymap_data, NULL,
+					 pdata->rows, pdata->cols,
+					 omap_kp->keymap, input_dev);
+	if (ret < 0)
+		goto err2;
+
+	ret = input_register_device(omap_kp->input);
+	if (ret < 0) {
+		printk(KERN_ERR "Unable to register omap-keypad input device\n");
+		goto err2;
+	}
+
+	if (pdata->dbounce)
+		omap_writew(0xff, OMAP1_MPUIO_BASE + OMAP_MPUIO_GPIO_DEBOUNCING);
+
+	/* scan current status and enable interrupt */
+	omap_kp_scan_keypad(omap_kp, keypad_state);
+	omap_kp->irq = platform_get_irq(pdev, 0);
+	if (omap_kp->irq >= 0) {
+		if (request_irq(omap_kp->irq, omap_kp_interrupt, 0,
+				"omap-keypad", omap_kp) < 0)
+			goto err3;
+	}
+	omap_writew(0, OMAP1_MPUIO_BASE + OMAP_MPUIO_KBD_MASKIT);
+
+	return 0;
+
+err3:
+	input_unregister_device(omap_kp->input);
+	input_dev = NULL;
+err2:
+	kfree(omap_kp);
+	input_free_device(input_dev);
+
+	return -EINVAL;
+}
+
+static void omap_kp_remove(struct platform_device *pdev)
+{
+	struct omap_kp *omap_kp = platform_get_drvdata(pdev);
+
+	/* disable keypad interrupt handling */
+	tasklet_disable(&kp_tasklet);
+	omap_writew(1, OMAP1_MPUIO_BASE + OMAP_MPUIO_KBD_MASKIT);
+	free_irq(omap_kp->irq, omap_kp);
+
+	timer_shutdown_sync(&omap_kp->timer);
+	tasklet_kill(&kp_tasklet);
+
+	/* unregister everything */
+	input_unregister_device(omap_kp->input);
+
+	kfree(omap_kp);
+}
+
+static struct platform_driver omap_kp_driver = {
+	.probe		= omap_kp_probe,
+	.remove		= omap_kp_remove,
+	.driver		= {
+		.name	= "omap-keypad",
+		.dev_groups = omap_kp_groups,
+	},
+};
+module_platform_driver(omap_kp_driver);
+
+MODULE_AUTHOR("Timo Teräs");
+MODULE_DESCRIPTION("OMAP Keypad Driver");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:omap-keypad");