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, 343 insertions, 0 deletions

diff --git a/drivers/i2c/busses/i2c-ljca.c b/drivers/i2c/busses/i2c-ljca.c
new file mode 100644
index 000000000..93274f0c2
--- /dev/null
+++ b/drivers/i2c/busses/i2c-ljca.c
@@ -0,0 +1,343 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Intel La Jolla Cove Adapter USB-I2C driver
+ *
+ * Copyright (c) 2023, Intel Corporation.
+ */
+
+#include <linux/acpi.h>
+#include <linux/auxiliary_bus.h>
+#include <linux/bitfield.h>
+#include <linux/bits.h>
+#include <linux/dev_printk.h>
+#include <linux/i2c.h>
+#include <linux/module.h>
+#include <linux/usb/ljca.h>
+
+/* I2C init flags */
+#define LJCA_I2C_INIT_FLAG_MODE			BIT(0)
+#define LJCA_I2C_INIT_FLAG_MODE_POLLING		FIELD_PREP(LJCA_I2C_INIT_FLAG_MODE, 0)
+#define LJCA_I2C_INIT_FLAG_MODE_INTERRUPT	FIELD_PREP(LJCA_I2C_INIT_FLAG_MODE, 1)
+
+#define LJCA_I2C_INIT_FLAG_ADDR_16BIT		BIT(0)
+
+#define LJCA_I2C_INIT_FLAG_FREQ			GENMASK(2, 1)
+#define LJCA_I2C_INIT_FLAG_FREQ_100K		FIELD_PREP(LJCA_I2C_INIT_FLAG_FREQ, 0)
+#define LJCA_I2C_INIT_FLAG_FREQ_400K		FIELD_PREP(LJCA_I2C_INIT_FLAG_FREQ, 1)
+#define LJCA_I2C_INIT_FLAG_FREQ_1M		FIELD_PREP(LJCA_I2C_INIT_FLAG_FREQ, 2)
+
+#define LJCA_I2C_BUF_SIZE			60u
+#define LJCA_I2C_MAX_XFER_SIZE			(LJCA_I2C_BUF_SIZE - sizeof(struct ljca_i2c_rw_packet))
+
+/* I2C commands */
+enum ljca_i2c_cmd {
+	LJCA_I2C_INIT = 1,
+	LJCA_I2C_XFER,
+	LJCA_I2C_START,
+	LJCA_I2C_STOP,
+	LJCA_I2C_READ,
+	LJCA_I2C_WRITE,
+};
+
+enum ljca_xfer_type {
+	LJCA_I2C_WRITE_XFER_TYPE,
+	LJCA_I2C_READ_XFER_TYPE,
+};
+
+/* I2C raw commands: Init/Start/Read/Write/Stop */
+struct ljca_i2c_rw_packet {
+	u8 id;
+	__le16 len;
+	u8 data[] __counted_by(len);
+} __packed;
+
+struct ljca_i2c_dev {
+	struct ljca_client *ljca;
+	struct ljca_i2c_info *i2c_info;
+	struct i2c_adapter adap;
+
+	u8 obuf[LJCA_I2C_BUF_SIZE];
+	u8 ibuf[LJCA_I2C_BUF_SIZE];
+};
+
+static int ljca_i2c_init(struct ljca_i2c_dev *ljca_i2c, u8 id)
+{
+	struct ljca_i2c_rw_packet *w_packet =
+			(struct ljca_i2c_rw_packet *)ljca_i2c->obuf;
+	int ret;
+
+	w_packet->id = id;
+	w_packet->len = cpu_to_le16(sizeof(*w_packet->data));
+	w_packet->data[0] = LJCA_I2C_INIT_FLAG_FREQ_400K;
+
+	ret = ljca_transfer(ljca_i2c->ljca, LJCA_I2C_INIT, (u8 *)w_packet,
+			    struct_size(w_packet, data, 1), NULL, 0);
+
+	return ret < 0 ? ret : 0;
+}
+
+static int ljca_i2c_start(struct ljca_i2c_dev *ljca_i2c, u8 target_addr,
+			  enum ljca_xfer_type type)
+{
+	struct ljca_i2c_rw_packet *w_packet =
+			(struct ljca_i2c_rw_packet *)ljca_i2c->obuf;
+	struct ljca_i2c_rw_packet *r_packet =
+			(struct ljca_i2c_rw_packet *)ljca_i2c->ibuf;
+	s16 rp_len;
+	int ret;
+
+	w_packet->id = ljca_i2c->i2c_info->id;
+	w_packet->len = cpu_to_le16(sizeof(*w_packet->data));
+	w_packet->data[0] = (target_addr << 1) | type;
+
+	ret = ljca_transfer(ljca_i2c->ljca, LJCA_I2C_START, (u8 *)w_packet,
+			    struct_size(w_packet, data, 1), (u8 *)r_packet,
+			    LJCA_I2C_BUF_SIZE);
+	if (ret < 0 || ret < sizeof(*r_packet))
+		return ret < 0 ? ret : -EIO;
+
+	rp_len = le16_to_cpu(r_packet->len);
+	if (rp_len < 0 || r_packet->id != w_packet->id) {
+		dev_dbg(&ljca_i2c->adap.dev,
+			"i2c start failed len: %d id: %d %d\n",
+			rp_len, r_packet->id, w_packet->id);
+		return -EIO;
+	}
+
+	return 0;
+}
+
+static void ljca_i2c_stop(struct ljca_i2c_dev *ljca_i2c)
+{
+	struct ljca_i2c_rw_packet *w_packet =
+			(struct ljca_i2c_rw_packet *)ljca_i2c->obuf;
+	struct ljca_i2c_rw_packet *r_packet =
+			(struct ljca_i2c_rw_packet *)ljca_i2c->ibuf;
+	s16 rp_len;
+	int ret;
+
+	w_packet->id = ljca_i2c->i2c_info->id;
+	w_packet->len = cpu_to_le16(sizeof(*w_packet->data));
+	w_packet->data[0] = 0;
+
+	ret = ljca_transfer(ljca_i2c->ljca, LJCA_I2C_STOP, (u8 *)w_packet,
+			    struct_size(w_packet, data, 1), (u8 *)r_packet,
+			    LJCA_I2C_BUF_SIZE);
+	if (ret < 0 || ret < sizeof(*r_packet)) {
+		dev_dbg(&ljca_i2c->adap.dev,
+			"i2c stop failed ret: %d id: %d\n",
+			ret, w_packet->id);
+		return;
+	}
+
+	rp_len = le16_to_cpu(r_packet->len);
+	if (rp_len < 0 || r_packet->id != w_packet->id)
+		dev_dbg(&ljca_i2c->adap.dev,
+			"i2c stop failed len: %d id: %d %d\n",
+			rp_len, r_packet->id, w_packet->id);
+}
+
+static int ljca_i2c_pure_read(struct ljca_i2c_dev *ljca_i2c, u8 *data, u8 len)
+{
+	struct ljca_i2c_rw_packet *w_packet =
+			(struct ljca_i2c_rw_packet *)ljca_i2c->obuf;
+	struct ljca_i2c_rw_packet *r_packet =
+			(struct ljca_i2c_rw_packet *)ljca_i2c->ibuf;
+	s16 rp_len;
+	int ret;
+
+	w_packet->id = ljca_i2c->i2c_info->id;
+	w_packet->len = cpu_to_le16(len);
+	w_packet->data[0] = 0;
+
+	ret = ljca_transfer(ljca_i2c->ljca, LJCA_I2C_READ, (u8 *)w_packet,
+			    struct_size(w_packet, data, 1), (u8 *)r_packet,
+			    LJCA_I2C_BUF_SIZE);
+	if (ret < 0 || ret < sizeof(*r_packet))
+		return ret < 0 ? ret : -EIO;
+
+	rp_len = le16_to_cpu(r_packet->len);
+	if (rp_len != len || r_packet->id != w_packet->id) {
+		dev_dbg(&ljca_i2c->adap.dev,
+			"i2c raw read failed len: %d id: %d %d\n",
+			rp_len, r_packet->id, w_packet->id);
+		return -EIO;
+	}
+
+	memcpy(data, r_packet->data, len);
+
+	return 0;
+}
+
+static int ljca_i2c_read(struct ljca_i2c_dev *ljca_i2c, u8 target_addr, u8 *data,
+			 u8 len)
+{
+	int ret;
+
+	ret = ljca_i2c_start(ljca_i2c, target_addr, LJCA_I2C_READ_XFER_TYPE);
+	if (!ret)
+		ret = ljca_i2c_pure_read(ljca_i2c, data, len);
+
+	ljca_i2c_stop(ljca_i2c);
+
+	return ret;
+}
+
+static int ljca_i2c_pure_write(struct ljca_i2c_dev *ljca_i2c, u8 *data, u8 len)
+{
+	struct ljca_i2c_rw_packet *w_packet =
+			(struct ljca_i2c_rw_packet *)ljca_i2c->obuf;
+	struct ljca_i2c_rw_packet *r_packet =
+			(struct ljca_i2c_rw_packet *)ljca_i2c->ibuf;
+	s16 rplen;
+	int ret;
+
+	w_packet->id = ljca_i2c->i2c_info->id;
+	w_packet->len = cpu_to_le16(len);
+	memcpy(w_packet->data, data, len);
+
+	ret = ljca_transfer(ljca_i2c->ljca, LJCA_I2C_WRITE, (u8 *)w_packet,
+			    struct_size(w_packet, data, len), (u8 *)r_packet,
+			    LJCA_I2C_BUF_SIZE);
+	if (ret < 0 || ret < sizeof(*r_packet))
+		return ret < 0 ? ret : -EIO;
+
+	rplen = le16_to_cpu(r_packet->len);
+	if (rplen != len || r_packet->id != w_packet->id) {
+		dev_dbg(&ljca_i2c->adap.dev,
+			"i2c write failed len: %d id: %d/%d\n",
+			rplen, r_packet->id, w_packet->id);
+		return -EIO;
+	}
+
+	return 0;
+}
+
+static int ljca_i2c_write(struct ljca_i2c_dev *ljca_i2c, u8 target_addr,
+			  u8 *data, u8 len)
+{
+	int ret;
+
+	ret = ljca_i2c_start(ljca_i2c, target_addr, LJCA_I2C_WRITE_XFER_TYPE);
+	if (!ret)
+		ret = ljca_i2c_pure_write(ljca_i2c, data, len);
+
+	ljca_i2c_stop(ljca_i2c);
+
+	return ret;
+}
+
+static int ljca_i2c_xfer(struct i2c_adapter *adapter, struct i2c_msg *msg,
+			 int num)
+{
+	struct ljca_i2c_dev *ljca_i2c;
+	struct i2c_msg *cur_msg;
+	int i, ret;
+
+	ljca_i2c = i2c_get_adapdata(adapter);
+	if (!ljca_i2c)
+		return -EINVAL;
+
+	for (i = 0; i < num; i++) {
+		cur_msg = &msg[i];
+		if (cur_msg->flags & I2C_M_RD)
+			ret = ljca_i2c_read(ljca_i2c, cur_msg->addr,
+					    cur_msg->buf, cur_msg->len);
+		else
+			ret = ljca_i2c_write(ljca_i2c, cur_msg->addr,
+					     cur_msg->buf, cur_msg->len);
+
+		if (ret)
+			return ret;
+	}
+
+	return num;
+}
+
+static u32 ljca_i2c_func(struct i2c_adapter *adap)
+{
+	return I2C_FUNC_I2C | (I2C_FUNC_SMBUS_EMUL & ~I2C_FUNC_SMBUS_QUICK);
+}
+
+static const struct i2c_adapter_quirks ljca_i2c_quirks = {
+	.flags = I2C_AQ_NO_ZERO_LEN,
+	.max_read_len = LJCA_I2C_MAX_XFER_SIZE,
+	.max_write_len = LJCA_I2C_MAX_XFER_SIZE,
+};
+
+static const struct i2c_algorithm ljca_i2c_algo = {
+	.xfer = ljca_i2c_xfer,
+	.functionality = ljca_i2c_func,
+};
+
+static int ljca_i2c_probe(struct auxiliary_device *auxdev,
+			  const struct auxiliary_device_id *aux_dev_id)
+{
+	struct ljca_client *ljca = auxiliary_dev_to_ljca_client(auxdev);
+	struct ljca_i2c_dev *ljca_i2c;
+	int ret;
+
+	ljca_i2c = devm_kzalloc(&auxdev->dev, sizeof(*ljca_i2c), GFP_KERNEL);
+	if (!ljca_i2c)
+		return -ENOMEM;
+
+	ljca_i2c->ljca = ljca;
+	ljca_i2c->i2c_info = dev_get_platdata(&auxdev->dev);
+
+	ljca_i2c->adap.owner = THIS_MODULE;
+	ljca_i2c->adap.class = I2C_CLASS_HWMON;
+	ljca_i2c->adap.algo = &ljca_i2c_algo;
+	ljca_i2c->adap.quirks = &ljca_i2c_quirks;
+	ljca_i2c->adap.dev.parent = &auxdev->dev;
+
+	snprintf(ljca_i2c->adap.name, sizeof(ljca_i2c->adap.name), "%s-%s-%d",
+		 dev_name(&auxdev->dev), dev_name(auxdev->dev.parent),
+		 ljca_i2c->i2c_info->id);
+
+	device_set_node(&ljca_i2c->adap.dev, dev_fwnode(&auxdev->dev));
+
+	i2c_set_adapdata(&ljca_i2c->adap, ljca_i2c);
+	auxiliary_set_drvdata(auxdev, ljca_i2c);
+
+	ret = ljca_i2c_init(ljca_i2c, ljca_i2c->i2c_info->id);
+	if (ret)
+		return dev_err_probe(&auxdev->dev, -EIO,
+				     "i2c init failed id: %d\n",
+				     ljca_i2c->i2c_info->id);
+
+	ret = devm_i2c_add_adapter(&auxdev->dev, &ljca_i2c->adap);
+	if (ret)
+		return ret;
+
+	if (has_acpi_companion(&ljca_i2c->adap.dev))
+		acpi_dev_clear_dependencies(ACPI_COMPANION(&ljca_i2c->adap.dev));
+
+	return 0;
+}
+
+static void ljca_i2c_remove(struct auxiliary_device *auxdev)
+{
+	struct ljca_i2c_dev *ljca_i2c = auxiliary_get_drvdata(auxdev);
+
+	i2c_del_adapter(&ljca_i2c->adap);
+}
+
+static const struct auxiliary_device_id ljca_i2c_id_table[] = {
+	{ "usb_ljca.ljca-i2c", 0 },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(auxiliary, ljca_i2c_id_table);
+
+static struct auxiliary_driver ljca_i2c_driver = {
+	.probe = ljca_i2c_probe,
+	.remove = ljca_i2c_remove,
+	.id_table = ljca_i2c_id_table,
+};
+module_auxiliary_driver(ljca_i2c_driver);
+
+MODULE_AUTHOR("Wentong Wu <wentong.wu@intel.com>");
+MODULE_AUTHOR("Zhifeng Wang <zhifeng.wang@intel.com>");
+MODULE_AUTHOR("Lixu Zhang <lixu.zhang@intel.com>");
+MODULE_DESCRIPTION("Intel La Jolla Cove Adapter USB-I2C driver");
+MODULE_LICENSE("GPL");
+MODULE_IMPORT_NS("LJCA");