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, 137 insertions, 0 deletions

diff --git a/Documentation/input/devices/ntrig.rst b/Documentation/input/devices/ntrig.rst
new file mode 100644
index 000000000..1559f5349
--- /dev/null
+++ b/Documentation/input/devices/ntrig.rst
@@ -0,0 +1,137 @@
+.. include:: <isonum.txt>
+
+=========================
+N-Trig touchscreen Driver
+=========================
+
+:Copyright: |copy| 2008-2010 Rafi Rubin <rafi@seas.upenn.edu>
+:Copyright: |copy| 2009-2010 Stephane Chatty
+
+This driver provides support for N-Trig pen and multi-touch sensors.  Single
+and multi-touch events are translated to the appropriate protocols for
+the hid and input systems.  Pen events are sufficiently hid compliant and
+are left to the hid core.  The driver also provides additional filtering
+and utility functions accessible with sysfs and module parameters.
+
+This driver has been reported to work properly with multiple N-Trig devices
+attached.
+
+
+Parameters
+----------
+
+Note: values set at load time are global and will apply to all applicable
+devices.  Adjusting parameters with sysfs will override the load time values,
+but only for that one device.
+
+The following parameters are used to configure filters to reduce noise:
+
++-----------------------+-----------------------------------------------------+
+|activate_slack		|number of fingers to ignore before processing events |
++-----------------------+-----------------------------------------------------+
+|activation_height,	|size threshold to activate immediately		      |
+|activation_width	|						      |
++-----------------------+-----------------------------------------------------+
+|min_height,		|size threshold below which fingers are ignored       |
+|min_width		|both to decide activation and during activity	      |
++-----------------------+-----------------------------------------------------+
+|deactivate_slack	|the number of "no contact" frames to ignore before   |
+|			|propagating the end of activity events		      |
++-----------------------+-----------------------------------------------------+
+
+When the last finger is removed from the device, it sends a number of empty
+frames.  By holding off on deactivation for a few frames we can tolerate false
+erroneous disconnects, where the sensor may mistakenly not detect a finger that
+is still present.  Thus deactivate_slack addresses problems where a users might
+see breaks in lines during drawing, or drop an object during a long drag.
+
+
+Additional sysfs items
+----------------------
+
+These nodes just provide easy access to the ranges reported by the device.
+
++-----------------------+-----------------------------------------------------+
+|sensor_logical_height, | the range for positions reported during activity    |
+|sensor_logical_width   |                                                     |
++-----------------------+-----------------------------------------------------+
+|sensor_physical_height,| internal ranges not used for normal events but      |
+|sensor_physical_width  | useful for tuning                                   |
++-----------------------+-----------------------------------------------------+
+
+All N-Trig devices with product id of 1 report events in the ranges of
+
+* X: 0-9600
+* Y: 0-7200
+
+However not all of these devices have the same physical dimensions.  Most
+seem to be 12" sensors (Dell Latitude XT and XT2 and the HP TX2), and
+at least one model (Dell Studio 17) has a 17" sensor.  The ratio of physical
+to logical sizes is used to adjust the size based filter parameters.
+
+
+Filtering
+---------
+
+With the release of the early multi-touch firmwares it became increasingly
+obvious that these sensors were prone to erroneous events.  Users reported
+seeing both inappropriately dropped contact and ghosts, contacts reported
+where no finger was actually touching the screen.
+
+Deactivation slack helps prevent dropped contact for single touch use, but does
+not address the problem of dropping one of more contacts while other contacts
+are still active.  Drops in the multi-touch context require additional
+processing and should be handled in tandem with tacking.
+
+As observed ghost contacts are similar to actual use of the sensor, but they
+seem to have different profiles.  Ghost activity typically shows up as small
+short lived touches.  As such, I assume that the longer the continuous stream
+of events the more likely those events are from a real contact, and that the
+larger the size of each contact the more likely it is real.  Balancing the
+goals of preventing ghosts and accepting real events quickly (to minimize
+user observable latency), the filter accumulates confidence for incoming
+events until it hits thresholds and begins propagating.  In the interest in
+minimizing stored state as well as the cost of operations to make a decision,
+I've kept that decision simple.
+
+Time is measured in terms of the number of fingers reported, not frames since
+the probability of multiple simultaneous ghosts is expected to drop off
+dramatically with increasing numbers.  Rather than accumulate weight as a
+function of size, I just use it as a binary threshold.  A sufficiently large
+contact immediately overrides the waiting period and leads to activation.
+
+Setting the activation size thresholds to large values will result in deciding
+primarily on activation slack.  If you see longer lived ghosts, turning up the
+activation slack while reducing the size thresholds may suffice to eliminate
+the ghosts while keeping the screen quite responsive to firm taps.
+
+Contacts continue to be filtered with min_height and min_width even after
+the initial activation filter is satisfied.  The intent is to provide
+a mechanism for filtering out ghosts in the form of an extra finger while
+you actually are using the screen.  In practice this sort of ghost has
+been far less problematic or relatively rare and I've left the defaults
+set to 0 for both parameters, effectively turning off that filter.
+
+I don't know what the optimal values are for these filters.  If the defaults
+don't work for you, please play with the parameters.  If you do find other
+values more comfortable, I would appreciate feedback.
+
+The calibration of these devices does drift over time.  If ghosts or contact
+dropping worsen and interfere with the normal usage of your device, try
+recalibrating it.
+
+
+Calibration
+-----------
+
+The N-Trig windows tools provide calibration and testing routines.  Also an
+unofficial unsupported set of user space tools including a calibrator is
+available at:
+http://code.launchpad.net/~rafi-seas/+junk/ntrig_calib
+
+
+Tracking
+--------
+
+As of yet, all tested N-Trig firmwares do not track fingers.  When multiple
+contacts are active they seem to be sorted primarily by Y position.