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, 348 insertions, 0 deletions

diff --git a/drivers/usb/phy/phy-generic.c b/drivers/usb/phy/phy-generic.c
new file mode 100644
index 000000000..de26b3023
--- /dev/null
+++ b/drivers/usb/phy/phy-generic.c
@@ -0,0 +1,348 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * NOP USB transceiver for all USB transceiver which are either built-in
+ * into USB IP or which are mostly autonomous.
+ *
+ * Copyright (C) 2009 Texas Instruments Inc
+ * Author: Ajay Kumar Gupta <ajay.gupta@ti.com>
+ *
+ * Current status:
+ *	This provides a "nop" transceiver for PHYs which are
+ *	autonomous such as isp1504, isp1707, etc.
+ */
+
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/dma-mapping.h>
+#include <linux/usb/gadget.h>
+#include <linux/usb/otg.h>
+#include <linux/usb/usb_phy_generic.h>
+#include <linux/slab.h>
+#include <linux/clk.h>
+#include <linux/regulator/consumer.h>
+#include <linux/property.h>
+#include <linux/gpio/consumer.h>
+#include <linux/delay.h>
+
+#include "phy-generic.h"
+
+#define VBUS_IRQ_FLAGS \
+	(IRQF_SHARED | IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING | \
+		IRQF_ONESHOT)
+
+struct platform_device *usb_phy_generic_register(void)
+{
+	return platform_device_register_simple("usb_phy_generic",
+			PLATFORM_DEVID_AUTO, NULL, 0);
+}
+EXPORT_SYMBOL_GPL(usb_phy_generic_register);
+
+void usb_phy_generic_unregister(struct platform_device *pdev)
+{
+	platform_device_unregister(pdev);
+}
+EXPORT_SYMBOL_GPL(usb_phy_generic_unregister);
+
+static int nop_set_suspend(struct usb_phy *x, int suspend)
+{
+	struct usb_phy_generic *nop = dev_get_drvdata(x->dev);
+	int ret = 0;
+
+	if (suspend) {
+		clk_disable_unprepare(nop->clk);
+		if (!IS_ERR(nop->vcc) && !device_may_wakeup(x->dev))
+			ret = regulator_disable(nop->vcc);
+	} else {
+		if (!IS_ERR(nop->vcc) && !device_may_wakeup(x->dev))
+			ret = regulator_enable(nop->vcc);
+		clk_prepare_enable(nop->clk);
+	}
+
+	return ret;
+}
+
+static void nop_reset(struct usb_phy_generic *nop)
+{
+	if (!nop->gpiod_reset)
+		return;
+
+	gpiod_set_value_cansleep(nop->gpiod_reset, 1);
+	usleep_range(10000, 20000);
+	gpiod_set_value_cansleep(nop->gpiod_reset, 0);
+	usleep_range(10000, 30000);
+}
+
+/* interface to regulator framework */
+static int nop_set_vbus(struct usb_otg *otg, bool enable)
+{
+	int ret = 0;
+	struct usb_phy_generic *nop = dev_get_drvdata(otg->usb_phy->dev);
+
+	if (!nop->vbus_draw)
+		return 0;
+
+	if (enable && !nop->vbus_draw_enabled) {
+		ret = regulator_enable(nop->vbus_draw);
+		if (ret)
+			nop->vbus_draw_enabled = false;
+		else
+			nop->vbus_draw_enabled = true;
+
+	} else if (!enable && nop->vbus_draw_enabled) {
+		ret = regulator_disable(nop->vbus_draw);
+		nop->vbus_draw_enabled = false;
+	}
+	return ret;
+}
+
+
+static irqreturn_t nop_gpio_vbus_thread(int irq, void *data)
+{
+	struct usb_phy_generic *nop = data;
+	struct usb_otg *otg = nop->phy.otg;
+	int vbus, status;
+
+	vbus = gpiod_get_value(nop->gpiod_vbus);
+	if ((vbus ^ nop->vbus) == 0)
+		return IRQ_HANDLED;
+	nop->vbus = vbus;
+
+	if (vbus) {
+		status = USB_EVENT_VBUS;
+		otg->state = OTG_STATE_B_PERIPHERAL;
+		nop->phy.last_event = status;
+
+		atomic_notifier_call_chain(&nop->phy.notifier, status,
+					   otg->gadget);
+	} else {
+		status = USB_EVENT_NONE;
+		otg->state = OTG_STATE_B_IDLE;
+		nop->phy.last_event = status;
+
+		atomic_notifier_call_chain(&nop->phy.notifier, status,
+					   otg->gadget);
+	}
+	return IRQ_HANDLED;
+}
+
+int usb_gen_phy_init(struct usb_phy *phy)
+{
+	struct usb_phy_generic *nop = dev_get_drvdata(phy->dev);
+	int ret;
+
+	if (!IS_ERR(nop->vcc)) {
+		if (regulator_enable(nop->vcc))
+			dev_err(phy->dev, "Failed to enable power\n");
+	}
+
+	ret = clk_prepare_enable(nop->clk);
+	if (ret)
+		return ret;
+
+	nop_reset(nop);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(usb_gen_phy_init);
+
+void usb_gen_phy_shutdown(struct usb_phy *phy)
+{
+	struct usb_phy_generic *nop = dev_get_drvdata(phy->dev);
+
+	gpiod_set_value_cansleep(nop->gpiod_reset, 1);
+
+	clk_disable_unprepare(nop->clk);
+
+	if (!IS_ERR(nop->vcc)) {
+		if (regulator_disable(nop->vcc))
+			dev_err(phy->dev, "Failed to disable power\n");
+	}
+}
+EXPORT_SYMBOL_GPL(usb_gen_phy_shutdown);
+
+static int nop_set_peripheral(struct usb_otg *otg, struct usb_gadget *gadget)
+{
+	if (!otg)
+		return -ENODEV;
+
+	if (!gadget) {
+		otg->gadget = NULL;
+		return -ENODEV;
+	}
+
+	otg->gadget = gadget;
+	if (otg->state == OTG_STATE_B_PERIPHERAL)
+		atomic_notifier_call_chain(&otg->usb_phy->notifier,
+					   USB_EVENT_VBUS, otg->gadget);
+	else
+		otg->state = OTG_STATE_B_IDLE;
+	return 0;
+}
+
+static int nop_set_host(struct usb_otg *otg, struct usb_bus *host)
+{
+	if (!otg)
+		return -ENODEV;
+
+	if (!host) {
+		otg->host = NULL;
+		return -ENODEV;
+	}
+
+	otg->host = host;
+	return 0;
+}
+
+int usb_phy_gen_create_phy(struct device *dev, struct usb_phy_generic *nop)
+{
+	enum usb_phy_type type = USB_PHY_TYPE_USB2;
+	int err = 0;
+	u32 clk_rate = 0;
+
+	device_property_read_u32(dev, "clock-frequency", &clk_rate);
+	nop->gpiod_reset = devm_gpiod_get_optional(dev, "reset",
+						   GPIOD_ASIS);
+	err = PTR_ERR_OR_ZERO(nop->gpiod_reset);
+	if (!err) {
+		nop->gpiod_vbus = devm_gpiod_get_optional(dev,
+						 "vbus-detect",
+						 GPIOD_ASIS);
+		err = PTR_ERR_OR_ZERO(nop->gpiod_vbus);
+	}
+
+	if (err)
+		return dev_err_probe(dev, err,
+				     "Error requesting RESET or VBUS GPIO\n");
+	if (nop->gpiod_reset)
+		gpiod_direction_output(nop->gpiod_reset, 1);
+
+	nop->phy.otg = devm_kzalloc(dev, sizeof(*nop->phy.otg),
+			GFP_KERNEL);
+	if (!nop->phy.otg)
+		return -ENOMEM;
+
+	nop->clk = devm_clk_get_optional(dev, "main_clk");
+	if (IS_ERR(nop->clk))
+		return dev_err_probe(dev, PTR_ERR(nop->clk),
+				     "Can't get phy clock\n");
+
+	if (clk_rate) {
+		err = clk_set_rate(nop->clk, clk_rate);
+		if (err)
+			return dev_err_probe(dev, err,
+					     "Error setting clock rate\n");
+	}
+
+	nop->vcc = devm_regulator_get_optional(dev, "vcc");
+	if (IS_ERR(nop->vcc) && PTR_ERR(nop->vcc) != -ENODEV)
+		return dev_err_probe(dev, PTR_ERR(nop->vcc),
+				     "could not get vcc regulator\n");
+
+	nop->vbus_draw = devm_regulator_get_exclusive(dev, "vbus");
+	if (PTR_ERR(nop->vbus_draw) == -ENODEV)
+		nop->vbus_draw = NULL;
+	if (IS_ERR(nop->vbus_draw))
+		return dev_err_probe(dev, PTR_ERR(nop->vbus_draw),
+				     "could not get vbus regulator\n");
+
+	nop->dev		= dev;
+	nop->phy.dev		= nop->dev;
+	nop->phy.label		= "nop-xceiv";
+	nop->phy.set_suspend	= nop_set_suspend;
+	nop->phy.type		= type;
+
+	nop->phy.otg->state		= OTG_STATE_UNDEFINED;
+	nop->phy.otg->usb_phy		= &nop->phy;
+	nop->phy.otg->set_host		= nop_set_host;
+	nop->phy.otg->set_peripheral	= nop_set_peripheral;
+	nop->phy.otg->set_vbus          = nop_set_vbus;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(usb_phy_gen_create_phy);
+
+static int usb_phy_generic_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct usb_phy_generic	*nop;
+	int err;
+
+	nop = devm_kzalloc(dev, sizeof(*nop), GFP_KERNEL);
+	if (!nop)
+		return -ENOMEM;
+
+	err = usb_phy_gen_create_phy(dev, nop);
+	if (err)
+		return err;
+
+	if (nop->gpiod_vbus) {
+		err = devm_request_threaded_irq(dev,
+						gpiod_to_irq(nop->gpiod_vbus),
+						NULL, nop_gpio_vbus_thread,
+						VBUS_IRQ_FLAGS, "vbus_detect",
+						nop);
+		if (err)
+			return dev_err_probe(dev, err, "can't request irq %i\n",
+					     gpiod_to_irq(nop->gpiod_vbus));
+
+		nop->phy.otg->state = gpiod_get_value(nop->gpiod_vbus) ?
+			OTG_STATE_B_PERIPHERAL : OTG_STATE_B_IDLE;
+	}
+
+	nop->phy.init		= usb_gen_phy_init;
+	nop->phy.shutdown	= usb_gen_phy_shutdown;
+
+	err = usb_add_phy_dev(&nop->phy);
+	if (err)
+		return dev_err_probe(dev, err, "can't register transceiver\n");
+
+	platform_set_drvdata(pdev, nop);
+
+	device_set_wakeup_capable(dev,
+				  device_property_read_bool(dev, "wakeup-source"));
+
+	return 0;
+}
+
+static void usb_phy_generic_remove(struct platform_device *pdev)
+{
+	struct usb_phy_generic *nop = platform_get_drvdata(pdev);
+
+	usb_remove_phy(&nop->phy);
+
+	if (nop->vbus_draw && nop->vbus_draw_enabled)
+		regulator_disable(nop->vbus_draw);
+}
+
+static const struct of_device_id nop_xceiv_dt_ids[] = {
+	{ .compatible = "usb-nop-xceiv" },
+	{ }
+};
+
+MODULE_DEVICE_TABLE(of, nop_xceiv_dt_ids);
+
+static struct platform_driver usb_phy_generic_driver = {
+	.probe		= usb_phy_generic_probe,
+	.remove		= usb_phy_generic_remove,
+	.driver		= {
+		.name	= "usb_phy_generic",
+		.of_match_table = nop_xceiv_dt_ids,
+	},
+};
+
+static int __init usb_phy_generic_init(void)
+{
+	return platform_driver_register(&usb_phy_generic_driver);
+}
+subsys_initcall(usb_phy_generic_init);
+
+static void __exit usb_phy_generic_exit(void)
+{
+	platform_driver_unregister(&usb_phy_generic_driver);
+}
+module_exit(usb_phy_generic_exit);
+
+MODULE_ALIAS("platform:usb_phy_generic");
+MODULE_AUTHOR("Texas Instruments Inc");
+MODULE_DESCRIPTION("NOP USB Transceiver driver");
+MODULE_LICENSE("GPL");