Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Fix error output of boot instance creation failure

   Currently if a boot instance creation fails, instead of printing out
   the name of the instance that failed, it prints "(null)". That is
   because it prints "cur_str" that had already been processed by
   strsep(). Print the saved name instead.

   While at it, print the error code of the failure.

 - Fix use-after-free for same named historgrams

   Histograms can be named so that they can be used in multiple events.
   But if the named histogram has a variable attached, the second event
   that uses the named histogram which duplicates it and needs to free
   the original after duplication leaves the old variable in place and
   still visible. If another histogram uses than variable, it will use
   the stale one which will try to reference the freed duplicate
   histogram and crash the kernel.

   Free the duplicate variables along with the duplicated histogram
   data.

 - Check return value of kthread_run() in event self test

   The events self tests uses a kthread for testing but does not check
   if it succeeded in creating a kthread. If the kthread creation were
   to fail, the code will still try to call kthread_stop() on the error
   returned.

 - Fix race between reading trace_pipe and updating subbuffer size

   If a user is reading the trace_pipe file at the same time they update
   the ring buffer sub-buffer size, can cause the trace_pipe read to
   read stale data. Add trace_access_lock() around updating the ring
   buffer sub-buffer size.

 - Fix eventfs_inode on failure path in creation of the events directory

   In the creation of the "events" directory, if after allocating the
   eventfs_inode a failure is detected, it calls cleanup_ei() which
   calls free_ei(). The free_ei() will test if eventfs_inode being freed
   has no children. It is a bug if it does. But on the failure case of
   the creation of the "events" directory, the children lists have not
   yet been initialized and the free will trigger a warning because
   list_empty() on an uninitialized list returns false.

   Move the initialization into init_ei() where it makes more sense and
   makes sure that a created eventfs_inode has its lists initialized
   upon creation.

 - Check return value of kthread_run() in ftrace direct sample code

   The sample code that shows how to use the ftrace direct calls does
   not test the return of kthread_run() to see if it succeeds. Return a
   failure if the kthread_run() doesn't succeed.

 - Clear user events state on fork in case of alloc failure

   On fork, the child gets a pointer to the parent's user events state.
   It makes a copy of it then updates the child's pointer to it. But if
   the allocation fails, the duplication function leaves the child with
   a pointer to its parent's descriptor. When the child cleans up its
   data, it will free the parent's descriptor while the parent is still
   using it.

   In the duplication function, set the child's user_event_mm to NULL
   before testing if the allocation succeeded, and when it exits it will
   not free the parent's descriptor.

 - Fix retry exhaustion in simple ring buffer reader swap

   simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
   post-decrements it only after a failed link replacement. On the final
   attempt, a successful replacement leaves retry at zero, while a
   failed replacement leaves it at -1.

   But the check for success expects the retry value to be non-zero and
   exits with an error on zero. This is the opposite result. Fix it.

 - Fail nicely when the remote swap_reader_page() returns an error

   Currently, if the swap_reader_page() of a remote buffer fails, it
   triggers a WARN_ON_ONCE() and continues normally. Instead, have it
   exit with an error and a pr_warn() print instead of a full WARNING.

* tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ring-buffer: Stop remote reader update when page swap fails
  tracing: Fix retry exhaustion in simple ring buffer reader swap
  tracing/user_events: Clear copied tracing state before fork duplication
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify
  eventfs: Initialize ei->children and ei->list in init_ei()
  tracing: Fix use-after-free in trace_pipe read on sub-buffer order change
  tracing: Fix crash passing ERR_PTR to kthread_stop()
  tracing: Fix use-after-free with same-name named triggers
  tracing: Fix logged instance name on creation failure

1 files changed, 216 insertions, 0 deletions

diff --git a/drivers/hwmon/ltc4151.c b/drivers/hwmon/ltc4151.c
new file mode 100644
index 000000000..fa7c57aae
--- /dev/null
+++ b/drivers/hwmon/ltc4151.c
@@ -0,0 +1,216 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Driver for Linear Technology LTC4151 High Voltage I2C Current
+ * and Voltage Monitor
+ *
+ * Copyright (C) 2011 AppearTV AS
+ *
+ * Derived from:
+ *
+ *  Driver for Linear Technology LTC4261 I2C Negative Voltage Hot
+ *  Swap Controller
+ *  Copyright (C) 2010 Ericsson AB.
+ *
+ * Datasheet: http://www.linear.com/docs/Datasheet/4151fc.pdf
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/init.h>
+#include <linux/err.h>
+#include <linux/slab.h>
+#include <linux/i2c.h>
+#include <linux/hwmon.h>
+#include <linux/hwmon-sysfs.h>
+#include <linux/jiffies.h>
+
+/* chip registers */
+#define LTC4151_SENSE_H	0x00
+#define LTC4151_SENSE_L	0x01
+#define LTC4151_VIN_H	0x02
+#define LTC4151_VIN_L	0x03
+#define LTC4151_ADIN_H	0x04
+#define LTC4151_ADIN_L	0x05
+
+struct ltc4151_data {
+	struct i2c_client *client;
+
+	struct mutex update_lock;
+	bool valid;
+	unsigned long last_updated; /* in jiffies */
+	unsigned int shunt; /* in micro ohms */
+
+	/* Registers */
+	u8 regs[6];
+};
+
+static struct ltc4151_data *ltc4151_update_device(struct device *dev)
+{
+	struct ltc4151_data *data = dev_get_drvdata(dev);
+	struct i2c_client *client = data->client;
+	struct ltc4151_data *ret = data;
+
+	mutex_lock(&data->update_lock);
+
+	/*
+	 * The chip's A/D updates 6 times per second
+	 * (Conversion Rate 6 - 9 Hz)
+	 */
+	if (time_after(jiffies, data->last_updated + HZ / 6) || !data->valid) {
+		int i;
+
+		dev_dbg(&client->dev, "Starting ltc4151 update\n");
+
+		/* Read all registers */
+		for (i = 0; i < ARRAY_SIZE(data->regs); i++) {
+			int val;
+
+			val = i2c_smbus_read_byte_data(client, i);
+			if (unlikely(val < 0)) {
+				dev_dbg(dev,
+					"Failed to read ADC value: error %d\n",
+					val);
+				ret = ERR_PTR(val);
+				goto abort;
+			}
+			data->regs[i] = val;
+		}
+		data->last_updated = jiffies;
+		data->valid = true;
+	}
+abort:
+	mutex_unlock(&data->update_lock);
+	return ret;
+}
+
+/* Return the voltage from the given register in mV */
+static int ltc4151_get_value(struct ltc4151_data *data, u8 reg)
+{
+	u32 val;
+
+	val = (data->regs[reg] << 4) + (data->regs[reg + 1] >> 4);
+
+	switch (reg) {
+	case LTC4151_ADIN_H:
+		/* 500uV resolution. Convert to mV. */
+		val = val * 500 / 1000;
+		break;
+	case LTC4151_SENSE_H:
+		/*
+		 * 20uV resolution. Convert to current as measured with
+		 * a given sense resistor, in mA.
+		 */
+		val = val * 20 * 1000 / data->shunt;
+		break;
+	case LTC4151_VIN_H:
+		/* 25 mV per increment */
+		val = val * 25;
+		break;
+	default:
+		/* If we get here, the developer messed up */
+		WARN_ON_ONCE(1);
+		val = 0;
+		break;
+	}
+
+	return val;
+}
+
+static ssize_t ltc4151_value_show(struct device *dev,
+				  struct device_attribute *da, char *buf)
+{
+	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
+	struct ltc4151_data *data = ltc4151_update_device(dev);
+	int value;
+
+	if (IS_ERR(data))
+		return PTR_ERR(data);
+
+	value = ltc4151_get_value(data, attr->index);
+	return sysfs_emit(buf, "%d\n", value);
+}
+
+/*
+ * Input voltages.
+ */
+static SENSOR_DEVICE_ATTR_RO(in1_input, ltc4151_value, LTC4151_VIN_H);
+static SENSOR_DEVICE_ATTR_RO(in2_input, ltc4151_value, LTC4151_ADIN_H);
+
+/* Currents (via sense resistor) */
+static SENSOR_DEVICE_ATTR_RO(curr1_input, ltc4151_value, LTC4151_SENSE_H);
+
+/*
+ * Finally, construct an array of pointers to members of the above objects,
+ * as required for sysfs_create_group()
+ */
+static struct attribute *ltc4151_attrs[] = {
+	&sensor_dev_attr_in1_input.dev_attr.attr,
+	&sensor_dev_attr_in2_input.dev_attr.attr,
+
+	&sensor_dev_attr_curr1_input.dev_attr.attr,
+
+	NULL,
+};
+ATTRIBUTE_GROUPS(ltc4151);
+
+static int ltc4151_probe(struct i2c_client *client)
+{
+	struct i2c_adapter *adapter = client->adapter;
+	struct device *dev = &client->dev;
+	struct ltc4151_data *data;
+	struct device *hwmon_dev;
+	u32 shunt;
+
+	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA))
+		return -ENODEV;
+
+	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	if (of_property_read_u32(client->dev.of_node,
+				 "shunt-resistor-micro-ohms", &shunt))
+		shunt = 1000; /* 1 mOhm if not set via DT */
+
+	if (shunt == 0)
+		return -EINVAL;
+
+	data->shunt = shunt;
+
+	data->client = client;
+	mutex_init(&data->update_lock);
+
+	hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
+							   data,
+							   ltc4151_groups);
+	return PTR_ERR_OR_ZERO(hwmon_dev);
+}
+
+static const struct i2c_device_id ltc4151_id[] = {
+	{ .name = "ltc4151" },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, ltc4151_id);
+
+static const struct of_device_id __maybe_unused ltc4151_match[] = {
+	{ .compatible = "lltc,ltc4151" },
+	{},
+};
+MODULE_DEVICE_TABLE(of, ltc4151_match);
+
+/* This is the driver that will be inserted */
+static struct i2c_driver ltc4151_driver = {
+	.driver = {
+		.name	= "ltc4151",
+		.of_match_table = of_match_ptr(ltc4151_match),
+	},
+	.probe		= ltc4151_probe,
+	.id_table	= ltc4151_id,
+};
+
+module_i2c_driver(ltc4151_driver);
+
+MODULE_AUTHOR("Per Dalen <per.dalen@appeartv.com>");
+MODULE_DESCRIPTION("LTC4151 driver");
+MODULE_LICENSE("GPL");