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, 281 insertions, 0 deletions

diff --git a/Documentation/input/input.rst b/Documentation/input/input.rst
new file mode 100644
index 000000000..7bbda39d8
--- /dev/null
+++ b/Documentation/input/input.rst
@@ -0,0 +1,281 @@
+.. include:: <isonum.txt>
+
+============
+Introduction
+============
+
+:Copyright: |copy| 1999-2001 Vojtech Pavlik <vojtech@ucw.cz> - Sponsored by SuSE
+
+Architecture
+============
+
+Input subsystem is a collection of drivers that is designed to support
+all input devices under Linux. Most of the drivers reside in
+drivers/input, although quite a few live in drivers/hid and
+drivers/platform.
+
+The core of the input subsystem is the input module, which must be
+loaded before any other of the input modules - it serves as a way of
+communication between two groups of modules:
+
+Device drivers
+--------------
+
+These modules talk to the hardware (for example via USB), and provide
+events (keystrokes, mouse movements) to the input module.
+
+Event handlers
+--------------
+
+These modules get events from input core and pass them where needed
+via various interfaces - keystrokes to the kernel, mouse movements via
+a simulated PS/2 interface to GPM and X, and so on.
+
+Simple Usage
+============
+
+For the most usual configuration, with one USB mouse and one USB keyboard,
+you'll have to load the following modules (or have them built in to the
+kernel)::
+
+	input
+	mousedev
+	usbcore
+	uhci_hcd or ohci_hcd or ehci_hcd
+	usbhid
+	hid_generic
+
+After this, the USB keyboard will work straight away, and the USB mouse
+will be available as a character device on major 13, minor 63::
+
+	crw-r--r--   1 root     root      13,  63 Mar 28 22:45 mice
+
+This device is usually created automatically by the system. The commands
+to create it by hand are::
+
+	cd /dev
+	mkdir input
+	mknod input/mice c 13 63
+
+After that you have to point GPM (the textmode mouse cut&paste tool) and
+XFree to this device to use it - GPM should be called like::
+
+	gpm -t ps2 -m /dev/input/mice
+
+And in X::
+
+	Section "Pointer"
+	    Protocol    "ImPS/2"
+	    Device      "/dev/input/mice"
+	    ZAxisMapping 4 5
+	EndSection
+
+When you do all of the above, you can use your USB mouse and keyboard.
+
+Detailed Description
+====================
+
+Event handlers
+--------------
+
+Event handlers distribute the events from the devices to userspace and
+in-kernel consumers, as needed.
+
+evdev
+~~~~~
+
+``evdev`` is the generic input event interface. It passes the events
+generated in the kernel straight to the program, with timestamps. The
+event codes are the same on all architectures and are hardware
+independent.
+
+This is the preferred interface for userspace to consume user
+input, and all clients are encouraged to use it.
+
+See :ref:`event-interface` for notes on API.
+
+The devices are in /dev/input::
+
+	crw-r--r--   1 root     root      13,  64 Apr  1 10:49 event0
+	crw-r--r--   1 root     root      13,  65 Apr  1 10:50 event1
+	crw-r--r--   1 root     root      13,  66 Apr  1 10:50 event2
+	crw-r--r--   1 root     root      13,  67 Apr  1 10:50 event3
+	...
+
+There are two ranges of minors: 64 through 95 is the static legacy
+range. If there are more than 32 input devices in a system, additional
+evdev nodes are created with minors starting with 256.
+
+keyboard
+~~~~~~~~
+
+``keyboard`` is in-kernel input handler and is a part of VT code. It
+consumes keyboard keystrokes and handles user input for VT consoles.
+
+mousedev
+~~~~~~~~
+
+``mousedev`` is a hack to make legacy programs that use mouse input
+work. It takes events from either mice or digitizers/tablets and makes
+a PS/2-style (a la /dev/psaux) mouse device available to the
+userland.
+
+Mousedev devices in /dev/input (as shown above) are::
+
+	crw-r--r--   1 root     root      13,  32 Mar 28 22:45 mouse0
+	crw-r--r--   1 root     root      13,  33 Mar 29 00:41 mouse1
+	crw-r--r--   1 root     root      13,  34 Mar 29 00:41 mouse2
+	crw-r--r--   1 root     root      13,  35 Apr  1 10:50 mouse3
+	...
+	...
+	crw-r--r--   1 root     root      13,  62 Apr  1 10:50 mouse30
+	crw-r--r--   1 root     root      13,  63 Apr  1 10:50 mice
+
+Each ``mouse`` device is assigned to a single mouse or digitizer, except
+the last one - ``mice``. This single character device is shared by all
+mice and digitizers, and even if none are connected, the device is
+present.  This is useful for hotplugging USB mice, so that older programs
+that do not handle hotplug can open the device even when no mice are
+present.
+
+CONFIG_INPUT_MOUSEDEV_SCREEN_[XY] in the kernel configuration are
+the size of your screen (in pixels) in XFree86. This is needed if you
+want to use your digitizer in X, because its movement is sent to X
+via a virtual PS/2 mouse and thus needs to be scaled
+accordingly. These values won't be used if you use a mouse only.
+
+Mousedev will generate either PS/2, ImPS/2 (Microsoft IntelliMouse) or
+ExplorerPS/2 (IntelliMouse Explorer) protocols, depending on what the
+program reading the data wishes. You can set GPM and X to any of
+these. You'll need ImPS/2 if you want to make use of a wheel on a USB
+mouse and ExplorerPS/2 if you want to use extra (up to 5) buttons.
+
+joydev
+~~~~~~
+
+``joydev`` implements v0.x and v1.x Linux joystick API. See
+:ref:`joystick-api` for details.
+
+As soon as any joystick is connected, it can be accessed in /dev/input on::
+
+	crw-r--r--   1 root     root      13,   0 Apr  1 10:50 js0
+	crw-r--r--   1 root     root      13,   1 Apr  1 10:50 js1
+	crw-r--r--   1 root     root      13,   2 Apr  1 10:50 js2
+	crw-r--r--   1 root     root      13,   3 Apr  1 10:50 js3
+	...
+
+And so on up to js31 in legacy range, and additional nodes with minors
+above 256 if there are more joystick devices.
+
+Device drivers
+--------------
+
+Device drivers are the modules that generate events.
+
+hid-generic
+~~~~~~~~~~~
+
+``hid-generic`` is one of the largest and most complex driver of the
+whole suite. It handles all HID devices, and because there is a very
+wide variety of them, and because the USB HID specification isn't
+simple, it needs to be this big.
+
+Currently, it handles USB mice, joysticks, gamepads, steering wheels,
+keyboards, trackballs and digitizers.
+
+However, USB uses HID also for monitor controls, speaker controls, UPSs,
+LCDs and many other purposes.
+
+The monitor and speaker controls should be easy to add to the hid/input
+interface, but for the UPSs and LCDs it doesn't make much sense. For this,
+the hiddev interface was designed. See Documentation/hid/hiddev.rst
+for more information about it.
+
+The usage of the usbhid module is very simple, it takes no parameters,
+detects everything automatically and when a HID device is inserted, it
+detects it appropriately.
+
+However, because the devices vary wildly, you might happen to have a
+device that doesn't work well. In that case #define DEBUG at the beginning
+of hid-core.c and send me the syslog traces.
+
+usbmouse
+~~~~~~~~
+
+For embedded systems, for mice with broken HID descriptors and just any
+other use when the big usbhid wouldn't be a good choice, there is the
+usbmouse driver. It handles USB mice only. It uses a simpler HIDBP
+protocol. This also means the mice must support this simpler protocol. Not
+all do. If you don't have any strong reason to use this module, use usbhid
+instead.
+
+usbkbd
+~~~~~~
+
+Much like usbmouse, this module talks to keyboards with a simplified
+HIDBP protocol. It's smaller, but doesn't support any extra special keys.
+Use usbhid instead if there isn't any special reason to use this.
+
+psmouse
+~~~~~~~
+
+This is driver for all flavors of pointing devices using PS/2
+protocol, including Synaptics and ALPS touchpads, Intellimouse
+Explorer devices, Logitech PS/2 mice and so on.
+
+atkbd
+~~~~~
+
+This is driver for PS/2 (AT) keyboards.
+
+iforce
+~~~~~~
+
+A driver for I-Force joysticks and wheels, both over USB and RS232.
+It includes Force Feedback support now, even though Immersion
+Corp. considers the protocol a trade secret and won't disclose a word
+about it.
+
+Verifying if it works
+=====================
+
+Typing a couple keys on the keyboard should be enough to check that
+a keyboard works and is correctly connected to the kernel keyboard
+driver.
+
+Doing a ``cat /dev/input/mouse0`` (c, 13, 32) will verify that a mouse
+is also emulated; characters should appear if you move it.
+
+You can test the joystick emulation with the ``jstest`` utility,
+available in the joystick package (see :ref:`joystick-doc`).
+
+You can test the event devices with the ``evtest`` utility.
+
+.. _event-interface:
+
+Event interface
+===============
+
+You can use blocking and nonblocking reads, and also select() on the
+/dev/input/eventX devices, and you'll always get a whole number of input
+events on a read. Their layout is::
+
+    struct input_event {
+	    struct timeval time;
+	    unsigned short type;
+	    unsigned short code;
+	    int value;
+    };
+
+``time`` is the timestamp, it returns the time at which the event happened.
+Type is for example EV_REL for relative movement, EV_KEY for a keypress or
+release. More types are defined in include/uapi/linux/input-event-codes.h.
+
+``code`` is event code, for example REL_X or KEY_BACKSPACE, again a complete
+list is in include/uapi/linux/input-event-codes.h.
+
+``value`` is the value the event carries. Either a relative change for
+EV_REL, absolute new value for EV_ABS (joysticks ...), or 0 for EV_KEY for
+release, 1 for keypress and 2 for autorepeat.
+
+See :ref:`input-event-codes` for more information about various event codes.