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, 265 insertions, 0 deletions

diff --git a/Documentation/input/ff.rst b/Documentation/input/ff.rst
new file mode 100644
index 000000000..5a1da42c3
--- /dev/null
+++ b/Documentation/input/ff.rst
@@ -0,0 +1,265 @@
+========================
+Force feedback for Linux
+========================
+
+:Author: Johann Deneux <johann.deneux@gmail.com> on 2001/04/22.
+:Updated: Anssi Hannula <anssi.hannula@gmail.com> on 2006/04/09.
+
+You may redistribute this file. Please remember to include shape.svg and
+interactive.svg as well.
+
+Introduction
+~~~~~~~~~~~~
+
+This document describes how to use force feedback devices under Linux. The
+goal is not to support these devices as if they were simple input-only devices
+(as it is already the case), but to really enable the rendering of force
+effects.
+This document only describes the force feedback part of the Linux input
+interface. Please read joydev/joystick.rst and input.rst before reading further
+this document.
+
+Instructions to the user
+~~~~~~~~~~~~~~~~~~~~~~~~
+
+To enable force feedback, you have to:
+
+1. have your kernel configured with evdev and a driver that supports your
+   device.
+2. make sure evdev module is loaded and /dev/input/event* device files are
+   created.
+
+Before you start, let me WARN you that some devices shake violently during the
+initialisation phase. This happens for example with my "AVB Top Shot Pegasus".
+To stop this annoying behaviour, move your joystick to its limits. Anyway, you
+should keep a hand on your device, in order to avoid it to break down if
+something goes wrong.
+
+If you have a serial iforce device, you need to start inputattach. See
+joydev/joystick.rst for details.
+
+Does it work ?
+--------------
+
+There is an utility called fftest that will allow you to test the driver::
+
+    % fftest /dev/input/eventXX
+
+Instructions to the developer
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+All interactions are done using the event API. That is, you can use ioctl()
+and write() on /dev/input/eventXX.
+This information is subject to change.
+
+Querying device capabilities
+----------------------------
+
+::
+
+    #include <linux/input.h>
+    #include <sys/ioctl.h>
+
+    #define BITS_TO_LONGS(x) \
+	    (((x) + 8 * sizeof (unsigned long) - 1) / (8 * sizeof (unsigned long)))
+    unsigned long features[BITS_TO_LONGS(FF_CNT)];
+    int ioctl(int file_descriptor, int request, unsigned long *features);
+
+"request" must be EVIOCGBIT(EV_FF, size of features array in bytes )
+
+Returns the features supported by the device. features is a bitfield with the
+following bits:
+
+- FF_CONSTANT	can render constant force effects
+- FF_PERIODIC	can render periodic effects with the following waveforms:
+
+  - FF_SQUARE	  square waveform
+  - FF_TRIANGLE	  triangle waveform
+  - FF_SINE	  sine waveform
+  - FF_SAW_UP	  sawtooth up waveform
+  - FF_SAW_DOWN	  sawtooth down waveform
+  - FF_CUSTOM	  custom waveform
+
+- FF_RAMP       can render ramp effects
+- FF_SPRING	can simulate the presence of a spring
+- FF_FRICTION	can simulate friction
+- FF_DAMPER	can simulate damper effects
+- FF_RUMBLE	rumble effects
+- FF_INERTIA    can simulate inertia
+- FF_GAIN	gain is adjustable
+- FF_AUTOCENTER	autocenter is adjustable
+
+.. note::
+
+    - In most cases you should use FF_PERIODIC instead of FF_RUMBLE. All
+      devices that support FF_RUMBLE support FF_PERIODIC (square, triangle,
+      sine) and the other way around.
+
+    - The exact syntax FF_CUSTOM is undefined for the time being as no driver
+      supports it yet.
+
+::
+
+    int ioctl(int fd, EVIOCGEFFECTS, int *n);
+
+Returns the number of effects the device can keep in its memory.
+
+Uploading effects to the device
+-------------------------------
+
+::
+
+    #include <linux/input.h>
+    #include <sys/ioctl.h>
+
+    int ioctl(int file_descriptor, int request, struct ff_effect *effect);
+
+"request" must be EVIOCSFF.
+
+"effect" points to a structure describing the effect to upload. The effect is
+uploaded, but not played.
+The content of effect may be modified. In particular, its field "id" is set
+to the unique id assigned by the driver. This data is required for performing
+some operations (removing an effect, controlling the playback).
+The "id" field must be set to -1 by the user in order to tell the driver to
+allocate a new effect.
+
+Effects are file descriptor specific.
+
+See <uapi/linux/input.h> for a description of the ff_effect struct.  You
+should also find help in a few sketches, contained in files shape.svg
+and interactive.svg:
+
+.. kernel-figure:: shape.svg
+
+    Shape
+
+.. kernel-figure:: interactive.svg
+
+    Interactive
+
+
+Removing an effect from the device
+----------------------------------
+
+::
+
+    int ioctl(int fd, EVIOCRMFF, effect.id);
+
+This makes room for new effects in the device's memory. Note that this also
+stops the effect if it was playing.
+
+Controlling the playback of effects
+-----------------------------------
+
+Control of playing is done with write(). Below is an example:
+
+::
+
+    #include <linux/input.h>
+    #include <unistd.h>
+
+	struct input_event play;
+	struct input_event stop;
+	struct ff_effect effect;
+	int fd;
+   ...
+	fd = open("/dev/input/eventXX", O_RDWR);
+   ...
+	/* Play three times */
+	play.type = EV_FF;
+	play.code = effect.id;
+	play.value = 3;
+
+	write(fd, (const void*) &play, sizeof(play));
+   ...
+	/* Stop an effect */
+	stop.type = EV_FF;
+	stop.code = effect.id;
+	stop.value = 0;
+
+	write(fd, (const void*) &stop, sizeof(stop));
+
+Setting the gain
+----------------
+
+Not all devices have the same strength. Therefore, users should set a gain
+factor depending on how strong they want effects to be. This setting is
+persistent across access to the driver.
+
+::
+
+    /* Set the gain of the device
+    int gain;		/* between 0 and 100 */
+    struct input_event ie;	/* structure used to communicate with the driver */
+
+    ie.type = EV_FF;
+    ie.code = FF_GAIN;
+    ie.value = 0xFFFFUL * gain / 100;
+
+    if (write(fd, &ie, sizeof(ie)) == -1)
+	perror("set gain");
+
+Enabling/Disabling autocenter
+-----------------------------
+
+The autocenter feature quite disturbs the rendering of effects in my opinion,
+and I think it should be an effect, which computation depends on the game
+type. But you can enable it if you want.
+
+::
+
+    int autocenter;		/* between 0 and 100 */
+    struct input_event ie;
+
+    ie.type = EV_FF;
+    ie.code = FF_AUTOCENTER;
+    ie.value = 0xFFFFUL * autocenter / 100;
+
+    if (write(fd, &ie, sizeof(ie)) == -1)
+	perror("set auto-center");
+
+A value of 0 means "no auto-center".
+
+Dynamic update of an effect
+---------------------------
+
+Proceed as if you wanted to upload a new effect, except that instead of
+setting the id field to -1, you set it to the wanted effect id.
+Normally, the effect is not stopped and restarted. However, depending on the
+type of device, not all parameters can be dynamically updated. For example,
+the direction of an effect cannot be updated with iforce devices. In this
+case, the driver stops the effect, up-load it, and restart it.
+
+Therefore it is recommended to dynamically change direction while the effect
+is playing only when it is ok to restart the effect with a replay count of 1.
+
+Information about the status of effects
+---------------------------------------
+
+Every time the status of an effect is changed, an event is sent. The values
+and meanings of the fields of the event are as follows::
+
+    struct input_event {
+    /* When the status of the effect changed */
+	    struct timeval time;
+
+    /* Set to EV_FF_STATUS */
+	    unsigned short type;
+
+    /* Contains the id of the effect */
+	    unsigned short code;
+
+    /* Indicates the status */
+	    unsigned int value;
+    };
+
+    FF_STATUS_STOPPED	The effect stopped playing
+    FF_STATUS_PLAYING	The effect started to play
+
+.. note::
+
+    - Status feedback is only supported by iforce driver. If you have
+      a really good reason to use this, please contact
+      linux-joystick@atrey.karlin.mff.cuni.cz or anssi.hannula@gmail.com
+      so that support for it can be added to the rest of the drivers.