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, 258 insertions, 0 deletions

diff --git a/drivers/phy/phy-can-transceiver.c b/drivers/phy/phy-can-transceiver.c
new file mode 100644
index 000000000..9aa306621
--- /dev/null
+++ b/drivers/phy/phy-can-transceiver.c
@@ -0,0 +1,258 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * phy-can-transceiver.c - phy driver for CAN transceivers
+ *
+ * Copyright (C) 2021 Texas Instruments Incorporated - https://www.ti.com
+ *
+ */
+#include <linux/gpio/consumer.h>
+#include <linux/phy/phy.h>
+#include <linux/platform_device.h>
+#include <linux/property.h>
+#include <linux/module.h>
+#include <linux/mux/consumer.h>
+
+struct can_transceiver_data {
+	u32 flags;
+#define CAN_TRANSCEIVER_STB_PRESENT	BIT(0)
+#define CAN_TRANSCEIVER_EN_PRESENT	BIT(1)
+#define CAN_TRANSCEIVER_DUAL_CH		BIT(2)
+#define CAN_TRANSCEIVER_SILENT_PRESENT	BIT(3)
+};
+
+struct can_transceiver_phy {
+	struct phy *generic_phy;
+	struct gpio_desc *silent_gpio;
+	struct gpio_desc *standby_gpio;
+	struct gpio_desc *enable_gpio;
+	struct can_transceiver_priv *priv;
+};
+
+struct can_transceiver_priv {
+	struct mux_state *mux_state;
+	int num_ch;
+	struct can_transceiver_phy can_transceiver_phy[] __counted_by(num_ch);
+};
+
+/* Power on function */
+static int can_transceiver_phy_power_on(struct phy *phy)
+{
+	struct can_transceiver_phy *can_transceiver_phy = phy_get_drvdata(phy);
+	struct can_transceiver_priv *priv = can_transceiver_phy->priv;
+	int ret;
+
+	if (priv->mux_state) {
+		ret = mux_state_select(priv->mux_state);
+		if (ret) {
+			dev_err(&phy->dev, "Failed to select CAN mux: %d\n", ret);
+			return ret;
+		}
+	}
+	gpiod_set_value_cansleep(can_transceiver_phy->silent_gpio, 0);
+	gpiod_set_value_cansleep(can_transceiver_phy->standby_gpio, 0);
+	gpiod_set_value_cansleep(can_transceiver_phy->enable_gpio, 1);
+
+	return 0;
+}
+
+/* Power off function */
+static int can_transceiver_phy_power_off(struct phy *phy)
+{
+	struct can_transceiver_phy *can_transceiver_phy = phy_get_drvdata(phy);
+	struct can_transceiver_priv *priv = can_transceiver_phy->priv;
+
+	gpiod_set_value_cansleep(can_transceiver_phy->silent_gpio, 1);
+	gpiod_set_value_cansleep(can_transceiver_phy->standby_gpio, 1);
+	gpiod_set_value_cansleep(can_transceiver_phy->enable_gpio, 0);
+	if (priv->mux_state)
+		mux_state_deselect(priv->mux_state);
+
+	return 0;
+}
+
+static const struct phy_ops can_transceiver_phy_ops = {
+	.power_on	= can_transceiver_phy_power_on,
+	.power_off	= can_transceiver_phy_power_off,
+	.owner		= THIS_MODULE,
+};
+
+static const struct can_transceiver_data tcan1042_drvdata = {
+	.flags = CAN_TRANSCEIVER_STB_PRESENT,
+};
+
+static const struct can_transceiver_data tcan1043_drvdata = {
+	.flags = CAN_TRANSCEIVER_STB_PRESENT | CAN_TRANSCEIVER_EN_PRESENT,
+};
+
+static const struct can_transceiver_data tja1048_drvdata = {
+	.flags = CAN_TRANSCEIVER_STB_PRESENT | CAN_TRANSCEIVER_DUAL_CH,
+};
+
+static const struct can_transceiver_data tja1051_drvdata = {
+	.flags = CAN_TRANSCEIVER_SILENT_PRESENT | CAN_TRANSCEIVER_EN_PRESENT,
+};
+
+static const struct can_transceiver_data tja1057_drvdata = {
+	.flags = CAN_TRANSCEIVER_SILENT_PRESENT,
+};
+
+static struct phy *can_transceiver_phy_xlate(struct device *dev,
+					     const struct of_phandle_args *args)
+{
+	struct can_transceiver_priv *priv = dev_get_drvdata(dev);
+	u32 idx;
+
+	if (priv->num_ch == 1)
+		return priv->can_transceiver_phy[0].generic_phy;
+
+	if (args->args_count != 1)
+		return ERR_PTR(-EINVAL);
+
+	idx = args->args[0];
+	if (idx >= priv->num_ch)
+		return ERR_PTR(-EINVAL);
+
+	return priv->can_transceiver_phy[idx].generic_phy;
+}
+
+static int can_transceiver_phy_probe(struct platform_device *pdev)
+{
+	struct phy_provider *phy_provider;
+	struct device *dev = &pdev->dev;
+	struct can_transceiver_phy *can_transceiver_phy;
+	struct can_transceiver_priv *priv;
+	const struct can_transceiver_data *drvdata;
+	struct phy *phy;
+	struct gpio_desc *silent_gpio;
+	struct gpio_desc *standby_gpio;
+	struct gpio_desc *enable_gpio;
+	struct mux_state *mux_state;
+	const char *propname;
+	int err, i, num_ch;
+	u32 max_bitrate;
+
+	drvdata = device_get_match_data(dev);
+	if (!drvdata)
+		return -ENODEV;
+
+	if (drvdata->flags & CAN_TRANSCEIVER_DUAL_CH)
+		num_ch = 2;
+	else
+		num_ch = 1;
+
+	priv = devm_kzalloc(dev, struct_size(priv, can_transceiver_phy, num_ch), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	priv->num_ch = num_ch;
+	platform_set_drvdata(pdev, priv);
+
+	mux_state = devm_mux_state_get_optional(dev, NULL);
+	if (IS_ERR(mux_state))
+		return PTR_ERR(mux_state);
+
+	priv->mux_state = mux_state;
+
+	propname = "max-bitrate";
+	if (device_property_present(dev, propname)) {
+		err = device_property_read_u32(dev, propname, &max_bitrate);
+		if (err)
+			return dev_err_probe(dev, err, "failed to parse %s\n", propname);
+
+		if (max_bitrate == 0)
+			dev_warn(dev, "Invalid value for transceiver max bitrate. Ignoring bitrate limit\n");
+	} else {
+		max_bitrate = 0;
+	}
+
+	for (i = 0; i < num_ch; i++) {
+		can_transceiver_phy = &priv->can_transceiver_phy[i];
+		can_transceiver_phy->priv = priv;
+
+		phy = devm_phy_create(dev, NULL, &can_transceiver_phy_ops);
+		if (IS_ERR(phy)) {
+			dev_err(dev, "failed to create can transceiver phy\n");
+			return PTR_ERR(phy);
+		}
+
+		phy->attrs.max_link_rate = max_bitrate;
+
+		can_transceiver_phy->generic_phy = phy;
+		can_transceiver_phy->priv = priv;
+
+		if (drvdata->flags & CAN_TRANSCEIVER_STB_PRESENT) {
+			standby_gpio = devm_gpiod_get_index_optional(dev, "standby", i,
+								     GPIOD_OUT_HIGH);
+			if (IS_ERR(standby_gpio))
+				return PTR_ERR(standby_gpio);
+			can_transceiver_phy->standby_gpio = standby_gpio;
+		}
+
+		if (drvdata->flags & CAN_TRANSCEIVER_EN_PRESENT) {
+			enable_gpio = devm_gpiod_get_index_optional(dev, "enable", i,
+								    GPIOD_OUT_LOW);
+			if (IS_ERR(enable_gpio))
+				return PTR_ERR(enable_gpio);
+			can_transceiver_phy->enable_gpio = enable_gpio;
+		}
+
+		if (drvdata->flags & CAN_TRANSCEIVER_SILENT_PRESENT) {
+			silent_gpio = devm_gpiod_get_index_optional(dev, "silent", i,
+								    GPIOD_OUT_HIGH);
+			if (IS_ERR(silent_gpio))
+				return PTR_ERR(silent_gpio);
+			can_transceiver_phy->silent_gpio = silent_gpio;
+		}
+
+		phy_set_drvdata(can_transceiver_phy->generic_phy, can_transceiver_phy);
+
+	}
+
+	phy_provider = devm_of_phy_provider_register(dev, can_transceiver_phy_xlate);
+
+	return PTR_ERR_OR_ZERO(phy_provider);
+}
+
+static const struct of_device_id can_transceiver_phy_ids[] = {
+	{
+		.compatible = "ti,tcan1042",
+		.data = &tcan1042_drvdata
+	},
+	{
+		.compatible = "ti,tcan1043",
+		.data = &tcan1043_drvdata
+	},
+	{
+		.compatible = "nxp,tja1048",
+		.data = &tja1048_drvdata
+	},
+	{
+		.compatible = "nxp,tja1051",
+		.data = &tja1051_drvdata
+	},
+	{
+		.compatible = "nxp,tja1057",
+		.data = &tja1057_drvdata
+	},
+	{
+		.compatible = "nxp,tjr1443",
+		.data = &tcan1043_drvdata
+	},
+	{ }
+};
+MODULE_DEVICE_TABLE(of, can_transceiver_phy_ids);
+
+static struct platform_driver can_transceiver_phy_driver = {
+	.probe = can_transceiver_phy_probe,
+	.driver = {
+		.name = "can-transceiver-phy",
+		.of_match_table = can_transceiver_phy_ids,
+	},
+};
+
+module_platform_driver(can_transceiver_phy_driver);
+
+MODULE_AUTHOR("Faiz Abbas <faiz_abbas@ti.com>");
+MODULE_AUTHOR("Aswath Govindraju <a-govindraju@ti.com>");
+MODULE_DESCRIPTION("CAN TRANSCEIVER PHY driver");
+MODULE_LICENSE("GPL v2");