Merge tag 'trace-v7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Don't destroy user event fields when removal fails

   User event fields are destroyed before the event is removed from
   visibility. But that can fail leaving the still visible event with no
   fields. Move the destroying of the fields to after the event is
   successfully removed from visibility.

 - Initialize function graph state is fork before calling
   copy_exec_state()

   For non-CLONE_VM forks, copy_exec_state() allocates a new
   task_exec_state. If that allocation fails, ftrace_graph_exit_task()
   will free the tasks ret_stack pointer. Since that pointer is still
   using the parent's ret_stack, it mistakenly frees the parent's
   pointer too.

   Call ftrace_graph_init() on the task first which will NULL out the
   new tasks's ret_stack and if the copy fails, it will not free
   anything.

 - Remove FGRAPH_MAX_INDEX

   The macro FGRAPH_MAX_INDEX was added but never used. Remove it.

 - Save ent_size in function graph printing of nested functions

   The function graph tracer needs to look at the next event to see if
   the next event is the return of the current function entry. If it is,
   it prints a single line:

	ktime_get();

   Otherwise it prints it like a nested function:

	tick_nohz_irq_exit() {
	    ktime_get();
	    kcpustat_irq_exit();
	}

   In order to look at the next event, it must save the current event so
   that it has the information to print from it. It saves the event in
   the iterator descriptor called "ent". What it doesn't save is the
   ent_size of the event which is now used to know if the function graph
   arguments are to be printed. The peek doesn't save the size so the
   size used happens to be that of the size of the last event that was
   seen.

   Save the entry event size in the iterator descriptor so that the
   correct size is used.

 - Fix several errors with freeing data in the histogram code

   The histogram code had a lot of leaked or or incorrect accounting
   when failures happen. Correct them.

 - Fix histogram regression of .percent and .graph modifiers

   Up until 6.3 histogram values could have "percent" or "graph"
   modifiers that changed how they were printed. But a change that added
   restricting histograms values from being strings, stack traces and
   other modifiers inadvertently prevented them from using the percent
   and graph modifiers, which were legal use cases for values.

   Put back the percent and graph modifiers.

 - Fix various typos in the comments

 - Set the trace_clock before initializing a histogram with clock
   argument

   The histogram API allows the user to specific which trace clock to
   use via a "clock=" string. The histogram is set up first before the
   clock is checked. If the passed in clock is not valid, it exits
   without fully fixing up the histogram leaving it on the list and a
   use-after-free can trigger.

   Update the clock argument first and if it fails then exit gracefully
   before the histogram trigger is placed on any lists.

 - Restore :mod: trailer after parsing in ftrace_set_clr_event

   The function ftrace_set_clr_event() modifies the parse string and
   needs to put it back to what was passed in. It searches for ":mod:"
   via a strsep() but fails to put back the first ':' in the string.

   Add back the ':' in the passed in string.

 - Take trace_array reference when opening a tracer options file

   The options files are dynamically created and some tracers add their
   own options. When a tracer adds their own list of options, the
   trace_array holding them has an array to hold the list of options for
   each tracer. This array increases in size via a krealloc(), and the
   new entry gets a newly allocated array to hold the options of the new
   tracer being added.

   The element in each entry of the tracer's option array holds a
   pointer back to the trace_array, a pointer to the tracer it is
   associated to, a pointer to the flags of the option.

   The issue is that these arrays are freed when the trace_array is
   freed when its instance it represents is removed from the instances
   directory. There's a race that an open of one of these options files
   can happen when the instance is being removed.

   Add a new helper function to be called by the open function of the
   options file to iterate all existing trace_arrays under a lock and
   find the one that has the given option element in one of it's tracer
   arrays. If found, then update the associated trace_array's reference
   counter to keep it from being freed. If not found, have the open call
   return -ENODEV.

 - Disable interrupts when acquiring the lock in rb_wake_up_waiters()

   The function rb_wake_up_waiters() assumes it will be called in
   interrupt context and does not disable irqs when taking
   cpu_buffer->reader_lock, which can be called in hard interrupt
   context. The issue is in PREEMPT_RT, this function is called in
   thread context leaving this lock open to a deadlock.

   Take the lock with interrupts disabled.

 - Use rcu_assign_pointer() for tmp_ops filter hash

   The tmp_ops used in update_ftrace_direct_mod() assigns its
   filter_hash field directly, but that field is annotated as __rcu and
   sparse complains. Assign it with rcu_assign_pointer()

 - Fix use-after-free in enable_trigger_private_data_free()

   The trace_event_call is accessed through the event_trigger_data's
   trace_event_file pointer to put the trace_event_call on freeing. The
   issue is that the trace_event_file data may have been freed already
   causing a use-after-free. Add a field to the event_trigger_data that
   points directly to the trace_event_call so that it can decrement its
   reference directly without needing to go through the
   trace_event_file.

 - Fix accounting of buffer data remote headers

   trace_buffer_desc_size() and trace_remote_alloc_buffer() undercount
   the number of pages is needed for the asked for size as it doesn't
   take into account the meta data on each page. Add a helper function
   to do the calculation properly and use that in these functions.

 - Catch nr_page_va overflow in ring_buffer_desc sizing

   The number of pages per remote ring buffer is capped by
   ring_buffer_desc::nr_page_va (32 bits). A buffer_size large enough to
   overflow that field would silently allocate a descriptor smaller than
   what was asked for.

 - Do not resize the subbuf order if any per_cpu buffer is disabled

   The mmapping of ring buffers disables resizing the subbuffers, but it
   is done per-cpu whereas the subbuf size change is done for all the
   per_cpu buffers under the buffer->mutex. It could change the size of
   some while the mapping is happening on others. Have the resize of the
   subbuf order check all the per_cpu buffers under the lock to see if
   any of them is disabled before starting and causing an inconsistency
   between buffers that are being mapped.

* tag 'trace-v7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (25 commits)
  ring-buffer: Check resize_disabled before publishing the new subbuf order
  tracing/remotes: Catch nr_page_va overflow in ring_buffer_desc sizing
  tracing/remotes: Account for ring buffer page header in size calculation
  tracing: Don't dereference trace_event_file in deferred trigger free
  ftrace: Use rcu_assign_pointer() for tmp_ops filter hash
  ring-buffer: Acquire the lock with irqsave in rb_wake_up_waiters()
  tracing: Take trace_array reference when opening a tracer options file
  tracing: Fix ring_buffer_read_page_size() kernel-doc
  tracing: Restore :mod: trailer after parsing in ftrace_set_clr_event()
  tracing: Fix memory corruption from a "STACKTRACE" histogram key
  tracing: Fix memory corruption from the histogram stacktrace modifier
  tracing: Undo the registration when enabling the histogram trigger fails
  tracing: Take the reference before publishing the named histogram trigger
  tracing: Set the trace clock before registering the histogram trigger
  tracing: Fix typo "preceeded" in comment
  tracing: Fix typo "availabe" in comment
  tracing: Let histogram values keep the percent and graph modifiers
  tracing: Keep the entry count when the histogram stats allocation fails
  tracing: Free histogram the field rejected for a bad modifier
  tracing: Free histogram the var ref when its initialization fails
  ...

1 files changed, 255 insertions, 0 deletions

diff --git a/Documentation/driver-api/extcon.rst b/Documentation/driver-api/extcon.rst
new file mode 100644
index 000000000..d3217b9cd
--- /dev/null
+++ b/Documentation/driver-api/extcon.rst
@@ -0,0 +1,255 @@
+=======================
+Extcon Device Subsystem
+=======================
+
+Overview
+========
+
+The Extcon (External Connector) subsystem provides a unified framework for
+managing external connectors in Linux systems. It allows drivers to report
+the state of external connectors and provides a standardized interface for
+userspace to query and monitor these states.
+
+Extcon is particularly useful in modern devices with multiple connectivity
+options, such as smartphones, tablets, and laptops. It helps manage various
+types of connectors, including:
+
+1. USB connectors (e.g., USB-C, micro-USB)
+2. Charging ports (e.g., fast charging, wireless charging)
+3. Audio jacks (e.g., 3.5mm headphone jack)
+4. Video outputs (e.g., HDMI, DisplayPort)
+5. Docking stations
+
+Real-world examples:
+
+1. Smartphone USB-C port:
+   A single USB-C port on a smartphone can serve multiple functions. Extcon
+   can manage the different states of this port, such as:
+   - USB data connection
+   - Charging (various types like fast charging, USB Power Delivery)
+   - Audio output (USB-C headphones)
+   - Video output (USB-C to HDMI adapter)
+
+2. Laptop docking station:
+   When a laptop is connected to a docking station, multiple connections are
+   made simultaneously. Extcon can handle the state changes for:
+   - Power delivery
+   - External displays
+   - USB hub connections
+   - Ethernet connectivity
+
+3. Wireless charging pad:
+   Extcon can manage the state of a wireless charging connection, allowing
+   the system to respond appropriately when a device is placed on or removed
+   from the charging pad.
+
+4. Smart TV HDMI ports:
+   In a smart TV, Extcon can manage multiple HDMI ports, detecting when
+   devices are connected or disconnected, and potentially identifying the
+   type of device (e.g., gaming console, set-top box, Blu-ray player).
+
+The Extcon framework simplifies the development of drivers for these complex
+scenarios by providing a standardized way to report and query connector
+states, handle mutually exclusive connections, and manage connector
+properties. This allows for more robust and flexible handling of external
+connections in modern devices.
+
+Key Components
+==============
+
+extcon_dev
+----------
+
+The core structure representing an Extcon device::
+
+    struct extcon_dev {
+        const char *name;
+        const unsigned int *supported_cable;
+        const u32 *mutually_exclusive;
+
+        /* Internal data */
+        struct device dev;
+        unsigned int id;
+        struct raw_notifier_head nh_all;
+        struct raw_notifier_head *nh;
+        struct list_head entry;
+        int max_supported;
+        spinlock_t lock;
+        u32 state;
+
+        /* Sysfs related */
+        struct device_type extcon_dev_type;
+        struct extcon_cable *cables;
+        struct attribute_group attr_g_muex;
+        struct attribute **attrs_muex;
+        struct device_attribute *d_attrs_muex;
+    };
+
+Key fields:
+
+- ``name``: Name of the Extcon device
+- ``supported_cable``: Array of supported cable types
+- ``mutually_exclusive``: Array defining mutually exclusive cable types
+  This field is crucial for enforcing hardware constraints. It's an array of
+  32-bit unsigned integers, where each element represents a set of mutually
+  exclusive cable types. The array should be terminated with a 0.
+
+  For example:
+
+  ::
+
+      static const u32 mutually_exclusive[] = {
+          BIT(0) | BIT(1),  /* Cable 0 and 1 are mutually exclusive */
+          BIT(2) | BIT(3) | BIT(4),  /* Cables 2, 3, and 4 are mutually exclusive */
+          0  /* Terminator */
+      };
+
+  In this example, cables 0 and 1 cannot be connected simultaneously, and
+  cables 2, 3, and 4 are also mutually exclusive. This is useful for
+  scenarios like a single port that can either be USB or HDMI, but not both
+  at the same time.
+
+  The Extcon core uses this information to prevent invalid combinations of
+  cable states, ensuring that the reported states are always consistent
+  with the hardware capabilities.
+
+- ``state``: Current state of the device (bitmap of connected cables)
+
+
+extcon_cable
+------------
+
+Represents an individual cable managed by an Extcon device::
+
+    struct extcon_cable {
+        struct extcon_dev *edev;
+        int cable_index;
+        struct attribute_group attr_g;
+        struct device_attribute attr_name;
+        struct device_attribute attr_state;
+        struct attribute *attrs[3];
+        union extcon_property_value usb_propval[EXTCON_PROP_USB_CNT];
+        union extcon_property_value chg_propval[EXTCON_PROP_CHG_CNT];
+        union extcon_property_value jack_propval[EXTCON_PROP_JACK_CNT];
+        union extcon_property_value disp_propval[EXTCON_PROP_DISP_CNT];
+        DECLARE_BITMAP(usb_bits, EXTCON_PROP_USB_CNT);
+        DECLARE_BITMAP(chg_bits, EXTCON_PROP_CHG_CNT);
+        DECLARE_BITMAP(jack_bits, EXTCON_PROP_JACK_CNT);
+        DECLARE_BITMAP(disp_bits, EXTCON_PROP_DISP_CNT);
+    };
+
+Core Functions
+==============
+
+.. kernel-doc:: drivers/extcon/extcon.c
+   :identifiers: extcon_get_state
+
+.. kernel-doc:: drivers/extcon/extcon.c
+   :identifiers: extcon_set_state
+
+.. kernel-doc:: drivers/extcon/extcon.c
+   :identifiers: extcon_set_state_sync
+
+.. kernel-doc:: drivers/extcon/extcon.c
+   :identifiers: extcon_get_property
+
+
+Sysfs Interface
+===============
+
+Extcon devices expose the following sysfs attributes:
+
+- ``name``: Name of the Extcon device
+- ``state``: Current state of all supported cables
+- ``cable.N/name``: Name of the Nth supported cable
+- ``cable.N/state``: State of the Nth supported cable
+
+Usage Example
+-------------
+
+.. code-block:: c
+
+    #include <linux/module.h>
+    #include <linux/platform_device.h>
+    #include <linux/extcon.h>
+
+    struct my_extcon_data {
+        struct extcon_dev *edev;
+        struct device *dev;
+    };
+
+    static const unsigned int my_extcon_cable[] = {
+        EXTCON_USB,
+        EXTCON_USB_HOST,
+        EXTCON_NONE,
+    };
+
+    static int my_extcon_probe(struct platform_device *pdev)
+    {
+        struct my_extcon_data *data;
+        int ret;
+
+        data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
+        if (!data)
+            return -ENOMEM;
+
+        data->dev = &pdev->dev;
+
+        /* Initialize extcon device */
+        data->edev = devm_extcon_dev_allocate(data->dev, my_extcon_cable);
+        if (IS_ERR(data->edev)) {
+            dev_err(data->dev, "Failed to allocate extcon device\n");
+            return PTR_ERR(data->edev);
+        }
+
+        /* Register extcon device */
+        ret = devm_extcon_dev_register(data->dev, data->edev);
+        if (ret < 0) {
+            dev_err(data->dev, "Failed to register extcon device\n");
+            return ret;
+        }
+
+        platform_set_drvdata(pdev, data);
+
+        /* Example: Set initial state */
+        extcon_set_state_sync(data->edev, EXTCON_USB, true);
+
+        dev_info(data->dev, "My extcon driver probed successfully\n");
+        return 0;
+    }
+
+    static int my_extcon_remove(struct platform_device *pdev)
+    {
+        struct my_extcon_data *data = platform_get_drvdata(pdev);
+
+        /* Example: Clear state before removal */
+        extcon_set_state_sync(data->edev, EXTCON_USB, false);
+
+        dev_info(data->dev, "My extcon driver removed\n");
+        return 0;
+    }
+
+    static const struct of_device_id my_extcon_of_match[] = {
+        { .compatible = "my,extcon-device", },
+        { },
+    };
+    MODULE_DEVICE_TABLE(of, my_extcon_of_match);
+
+    static struct platform_driver my_extcon_driver = {
+        .driver = {
+            .name = "my-extcon-driver",
+            .of_match_table = my_extcon_of_match,
+        },
+        .probe = my_extcon_probe,
+        .remove = my_extcon_remove,
+    };
+
+    module_platform_driver(my_extcon_driver);
+
+This example demonstrates:
+---------------------------
+
+- Defining supported cable types (USB and USB Host in this case).
+- Allocating and registering an extcon device.
+- Setting an initial state for a cable (USB connected in this example).
+- Clearing the state when the driver is removed.