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, 252 insertions, 0 deletions

diff --git a/Documentation/gpu/drm-internals.rst b/Documentation/gpu/drm-internals.rst
new file mode 100644
index 000000000..a3ce25a36
--- /dev/null
+++ b/Documentation/gpu/drm-internals.rst
@@ -0,0 +1,252 @@
+=============
+DRM Internals
+=============
+
+This chapter documents DRM internals relevant to driver authors and
+developers working to add support for the latest features to existing
+drivers.
+
+First, we go over some typical driver initialization requirements, like
+setting up command buffers, creating an initial output configuration,
+and initializing core services. Subsequent sections cover core internals
+in more detail, providing implementation notes and examples.
+
+The DRM layer provides several services to graphics drivers, many of
+them driven by the application interfaces it provides through libdrm,
+the library that wraps most of the DRM ioctls. These include vblank
+event handling, memory management, output management, framebuffer
+management, command submission & fencing, suspend/resume support, and
+DMA services.
+
+.. contents::
+
+Driver Initialization
+=====================
+
+At the core of every DRM driver is a :c:type:`struct drm_driver
+<drm_driver>` structure. Drivers typically statically initialize
+a drm_driver structure, and then pass it to
+drm_dev_alloc() to allocate a device instance. After the
+device instance is fully initialized it can be registered (which makes
+it accessible from userspace) using drm_dev_register().
+
+The :c:type:`struct drm_driver <drm_driver>` structure
+contains static information that describes the driver and features it
+supports, and pointers to methods that the DRM core will call to
+implement the DRM API. We will first go through the :c:type:`struct
+drm_driver <drm_driver>` static information fields, and will
+then describe individual operations in details as they get used in later
+sections.
+
+Driver Information
+------------------
+
+Major, Minor and Patchlevel
+~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+int major; int minor; int patchlevel;
+The DRM core identifies driver versions by a major, minor and patch
+level triplet. The information is printed to the kernel log at
+initialization time and passed to userspace through the
+DRM_IOCTL_VERSION ioctl.
+
+The major and minor numbers are also used to verify the requested driver
+API version passed to DRM_IOCTL_SET_VERSION. When the driver API
+changes between minor versions, applications can call
+DRM_IOCTL_SET_VERSION to select a specific version of the API. If the
+requested major isn't equal to the driver major, or the requested minor
+is larger than the driver minor, the DRM_IOCTL_SET_VERSION call will
+return an error. Otherwise the driver's set_version() method will be
+called with the requested version.
+
+Name and Description
+~~~~~~~~~~~~~~~~~~~~
+
+char \*name; char \*desc; char \*date;
+The driver name is printed to the kernel log at initialization time,
+used for IRQ registration and passed to userspace through
+DRM_IOCTL_VERSION.
+
+The driver description is a purely informative string passed to
+userspace through the DRM_IOCTL_VERSION ioctl and otherwise unused by
+the kernel.
+
+Module Initialization
+---------------------
+
+.. kernel-doc:: include/drm/drm_module.h
+   :doc: overview
+
+Device Instance and Driver Handling
+-----------------------------------
+
+.. kernel-doc:: drivers/gpu/drm/drm_drv.c
+   :doc: driver instance overview
+
+.. kernel-doc:: include/drm/drm_device.h
+   :internal:
+
+.. kernel-doc:: include/drm/drm_drv.h
+   :internal:
+
+.. kernel-doc:: drivers/gpu/drm/drm_drv.c
+   :export:
+
+Driver Load
+-----------
+
+Component Helper Usage
+~~~~~~~~~~~~~~~~~~~~~~
+
+.. kernel-doc:: drivers/gpu/drm/drm_drv.c
+   :doc: component helper usage recommendations
+
+Memory Manager Initialization
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Every DRM driver requires a memory manager which must be initialized at
+load time. DRM currently contains two memory managers, the Translation
+Table Manager (TTM) and the Graphics Execution Manager (GEM). This
+document describes the use of the GEM memory manager only. See ? for
+details.
+
+Miscellaneous Device Configuration
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Another task that may be necessary for PCI devices during configuration
+is mapping the video BIOS. On many devices, the VBIOS describes device
+configuration, LCD panel timings (if any), and contains flags indicating
+device state. Mapping the BIOS can be done using the pci_map_rom()
+call, a convenience function that takes care of mapping the actual ROM,
+whether it has been shadowed into memory (typically at address 0xc0000)
+or exists on the PCI device in the ROM BAR. Note that after the ROM has
+been mapped and any necessary information has been extracted, it should
+be unmapped; on many devices, the ROM address decoder is shared with
+other BARs, so leaving it mapped could cause undesired behaviour like
+hangs or memory corruption.
+
+Managed Resources
+-----------------
+
+.. kernel-doc:: drivers/gpu/drm/drm_managed.c
+   :doc: managed resources
+
+.. kernel-doc:: drivers/gpu/drm/drm_managed.c
+   :export:
+
+.. kernel-doc:: include/drm/drm_managed.h
+   :internal:
+
+Open/Close, File Operations and IOCTLs
+======================================
+
+.. _drm_driver_fops:
+
+File Operations
+---------------
+
+.. kernel-doc:: drivers/gpu/drm/drm_file.c
+   :doc: file operations
+
+.. kernel-doc:: include/drm/drm_file.h
+   :internal:
+
+.. kernel-doc:: drivers/gpu/drm/drm_file.c
+   :export:
+
+Misc Utilities
+==============
+
+Printer
+-------
+
+.. kernel-doc:: include/drm/drm_print.h
+   :doc: print
+
+.. kernel-doc:: include/drm/drm_print.h
+   :internal:
+
+.. kernel-doc:: drivers/gpu/drm/drm_print.c
+   :export:
+
+Utilities
+---------
+
+.. kernel-doc:: include/drm/drm_util.h
+   :doc: drm utils
+
+.. kernel-doc:: include/drm/drm_util.h
+   :internal:
+
+
+Unit testing
+============
+
+KUnit
+-----
+
+KUnit (Kernel unit testing framework) provides a common framework for unit tests
+within the Linux kernel.
+
+This section covers the specifics for the DRM subsystem. For general information
+about KUnit, please refer to Documentation/dev-tools/kunit/start.rst.
+
+How to run the tests?
+~~~~~~~~~~~~~~~~~~~~~
+
+In order to facilitate running the test suite, a configuration file is present
+in ``drivers/gpu/drm/tests/.kunitconfig``. It can be used by ``kunit.py`` as
+follows:
+
+.. code-block:: bash
+
+	$ ./tools/testing/kunit/kunit.py run --kunitconfig=drivers/gpu/drm/tests \
+		--kconfig_add CONFIG_VIRTIO_UML=y \
+		--kconfig_add CONFIG_UML_PCI_OVER_VIRTIO=y
+
+.. note::
+	The configuration included in ``.kunitconfig`` should be as generic as
+	possible.
+	``CONFIG_VIRTIO_UML`` and ``CONFIG_UML_PCI_OVER_VIRTIO`` are not
+	included in it because they are only required for User Mode Linux.
+
+KUnit Coverage Rules
+~~~~~~~~~~~~~~~~~~~~
+
+KUnit support is gradually added to the DRM framework and helpers. There's no
+general requirement for the framework and helpers to have KUnit tests at the
+moment. However, patches that are affecting a function or helper already
+covered by KUnit tests must provide tests if the change calls for one.
+
+Legacy Support Code
+===================
+
+The section very briefly covers some of the old legacy support code
+which is only used by old DRM drivers which have done a so-called
+shadow-attach to the underlying device instead of registering as a real
+driver. This also includes some of the old generic buffer management and
+command submission code. Do not use any of this in new and modern
+drivers.
+
+Legacy Suspend/Resume
+---------------------
+
+The DRM core provides some suspend/resume code, but drivers wanting full
+suspend/resume support should provide save() and restore() functions.
+These are called at suspend, hibernate, or resume time, and should
+perform any state save or restore required by your device across suspend
+or hibernate states.
+
+int (\*suspend) (struct drm_device \*, pm_message_t state); int
+(\*resume) (struct drm_device \*);
+Those are legacy suspend and resume methods which *only* work with the
+legacy shadow-attach driver registration functions. New driver should
+use the power management interface provided by their bus type (usually
+through the :c:type:`struct device_driver <device_driver>`
+dev_pm_ops) and set these methods to NULL.
+
+Legacy DMA Services
+-------------------
+
+This should cover how DMA mapping etc. is supported by the core. These
+functions are deprecated and should not be used.