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, 118 insertions, 0 deletions

diff --git a/drivers/usb/phy/phy-keystone.c b/drivers/usb/phy/phy-keystone.c
new file mode 100644
index 000000000..51155c551
--- /dev/null
+++ b/drivers/usb/phy/phy-keystone.c
@@ -0,0 +1,118 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * phy-keystone - USB PHY, talking to dwc3 controller in Keystone.
+ *
+ * Copyright (C) 2013 Texas Instruments Incorporated - https://www.ti.com
+ *
+ * Author: WingMan Kwok <w-kwok2@ti.com>
+ */
+
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/usb/usb_phy_generic.h>
+#include <linux/io.h>
+#include <linux/of.h>
+
+#include "phy-generic.h"
+
+/* USB PHY control register offsets */
+#define USB_PHY_CTL_UTMI		0x0000
+#define USB_PHY_CTL_PIPE		0x0004
+#define USB_PHY_CTL_PARAM_1		0x0008
+#define USB_PHY_CTL_PARAM_2		0x000c
+#define USB_PHY_CTL_CLOCK		0x0010
+#define USB_PHY_CTL_PLL			0x0014
+
+#define PHY_REF_SSP_EN			BIT(29)
+
+struct keystone_usbphy {
+	struct usb_phy_generic	usb_phy_gen;
+	void __iomem			*phy_ctrl;
+};
+
+static inline u32 keystone_usbphy_readl(void __iomem *base, u32 offset)
+{
+	return readl(base + offset);
+}
+
+static inline void keystone_usbphy_writel(void __iomem *base,
+					  u32 offset, u32 value)
+{
+	writel(value, base + offset);
+}
+
+static int keystone_usbphy_init(struct usb_phy *phy)
+{
+	struct keystone_usbphy *k_phy = dev_get_drvdata(phy->dev);
+	u32 val;
+
+	val  = keystone_usbphy_readl(k_phy->phy_ctrl, USB_PHY_CTL_CLOCK);
+	keystone_usbphy_writel(k_phy->phy_ctrl, USB_PHY_CTL_CLOCK,
+				val | PHY_REF_SSP_EN);
+	return 0;
+}
+
+static void keystone_usbphy_shutdown(struct usb_phy *phy)
+{
+	struct keystone_usbphy *k_phy = dev_get_drvdata(phy->dev);
+	u32 val;
+
+	val  = keystone_usbphy_readl(k_phy->phy_ctrl, USB_PHY_CTL_CLOCK);
+	keystone_usbphy_writel(k_phy->phy_ctrl, USB_PHY_CTL_CLOCK,
+				val & ~PHY_REF_SSP_EN);
+}
+
+static int keystone_usbphy_probe(struct platform_device *pdev)
+{
+	struct device		*dev = &pdev->dev;
+	struct keystone_usbphy	*k_phy;
+	int ret;
+
+	k_phy = devm_kzalloc(dev, sizeof(*k_phy), GFP_KERNEL);
+	if (!k_phy)
+		return -ENOMEM;
+
+	k_phy->phy_ctrl = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(k_phy->phy_ctrl))
+		return PTR_ERR(k_phy->phy_ctrl);
+
+	ret = usb_phy_gen_create_phy(dev, &k_phy->usb_phy_gen);
+	if (ret)
+		return ret;
+
+	k_phy->usb_phy_gen.phy.init = keystone_usbphy_init;
+	k_phy->usb_phy_gen.phy.shutdown = keystone_usbphy_shutdown;
+
+	platform_set_drvdata(pdev, k_phy);
+
+	return usb_add_phy_dev(&k_phy->usb_phy_gen.phy);
+}
+
+static void keystone_usbphy_remove(struct platform_device *pdev)
+{
+	struct keystone_usbphy *k_phy = platform_get_drvdata(pdev);
+
+	usb_remove_phy(&k_phy->usb_phy_gen.phy);
+}
+
+static const struct of_device_id keystone_usbphy_ids[] = {
+	{ .compatible = "ti,keystone-usbphy" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, keystone_usbphy_ids);
+
+static struct platform_driver keystone_usbphy_driver = {
+	.probe          = keystone_usbphy_probe,
+	.remove         = keystone_usbphy_remove,
+	.driver         = {
+		.name   = "keystone-usbphy",
+		.of_match_table = keystone_usbphy_ids,
+	},
+};
+
+module_platform_driver(keystone_usbphy_driver);
+
+MODULE_ALIAS("platform:keystone-usbphy");
+MODULE_AUTHOR("Texas Instruments Inc.");
+MODULE_DESCRIPTION("Keystone USB phy driver");
+MODULE_LICENSE("GPL v2");