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, 172 insertions, 0 deletions

diff --git a/Documentation/gpu/automated_testing.rst b/Documentation/gpu/automated_testing.rst
new file mode 100644
index 000000000..8a7328aef
--- /dev/null
+++ b/Documentation/gpu/automated_testing.rst
@@ -0,0 +1,172 @@
+.. SPDX-License-Identifier: GPL-2.0+
+
+=========================================
+Automated testing of the DRM subsystem
+=========================================
+
+Introduction
+============
+
+Making sure that changes to the core or drivers don't introduce regressions can
+be very time-consuming when lots of different hardware configurations need to
+be tested. Moreover, it isn't practical for each person interested in this
+testing to have to acquire and maintain what can be a considerable amount of
+hardware.
+
+Also, it is desirable for developers to check for regressions in their code by
+themselves, instead of relying on the maintainers to find them and then
+reporting back.
+
+There are facilities in gitlab.freedesktop.org to automatically test Mesa that
+can be used as well for testing the DRM subsystem. This document explains how
+people interested in testing it can use this shared infrastructure to save
+quite some time and effort.
+
+
+Relevant files
+==============
+
+drivers/gpu/drm/ci/gitlab-ci.yml
+--------------------------------
+
+This is the root configuration file for GitLab CI. Among other less interesting
+bits, it specifies the specific version of the scripts to be used. There are
+some variables that can be modified to change the behavior of the pipeline:
+
+DRM_CI_PROJECT_PATH
+    Repository that contains the Mesa software infrastructure for CI
+
+DRM_CI_COMMIT_SHA
+    A particular revision to use from that repository
+
+UPSTREAM_REPO
+    URL to git repository containing the target branch
+
+TARGET_BRANCH
+    Branch to which this branch is to be merged into
+
+IGT_VERSION
+    Revision of igt-gpu-tools being used, from
+    https://gitlab.freedesktop.org/drm/igt-gpu-tools
+
+drivers/gpu/drm/ci/testlist.txt
+-------------------------------
+
+IGT tests to be run on all drivers (unless mentioned in a driver's \*-skips.txt
+file, see below).
+
+drivers/gpu/drm/ci/${DRIVER_NAME}-${HW_REVISION}-fails.txt
+----------------------------------------------------------
+
+Lists the known failures for a given driver on a specific hardware revision.
+
+drivers/gpu/drm/ci/${DRIVER_NAME}-${HW_REVISION}-flakes.txt
+-----------------------------------------------------------
+
+Lists the tests that for a given driver on a specific hardware revision are
+known to behave unreliably. These tests won't cause a job to fail regardless of
+the result. They will still be run.
+
+Each new flake entry must be associated with a link to the email reporting the
+bug to the author of the affected driver or the relevant GitLab issue. The entry
+must also include the board name or Device Tree name, the first kernel version
+affected, the IGT version used for tests, and an approximation of the failure rate.
+
+They should be provided under the following format::
+
+  # Bug Report: $LORE_URL_OR_GITLAB_ISSUE
+  # Board Name: broken-board.dtb
+  # Linux Version: 6.6-rc1
+  # IGT Version: 1.28-gd2af13d9f
+  # Failure Rate: 100
+  flaky-test
+
+Use the appropriate link below to create a GitLab issue:
+amdgpu driver: https://gitlab.freedesktop.org/drm/amd/-/issues
+i915 driver: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues
+msm driver: https://gitlab.freedesktop.org/drm/msm/-/issues
+xe driver: https://gitlab.freedesktop.org/drm/xe/kernel/-/issues
+
+drivers/gpu/drm/ci/${DRIVER_NAME}-${HW_REVISION}-skips.txt
+-----------------------------------------------------------
+
+Lists the tests that won't be run for a given driver on a specific hardware
+revision. These are usually tests that interfere with the running of the test
+list due to hanging the machine, causing OOM, taking too long, etc.
+
+
+How to enable automated testing on your tree
+============================================
+
+1. Create a Linux tree in https://gitlab.freedesktop.org/ if you don't have one
+yet, by forking https://gitlab.freedesktop.org/drm/kernel (this allows GitLab
+to internally track that these are the same git objects).
+
+2. In your kernel repo's configuration (eg.
+https://gitlab.freedesktop.org/janedoe/linux/-/settings/ci_cd), change the
+CI/CD configuration file from .gitlab-ci.yml to
+drivers/gpu/drm/ci/gitlab-ci.yml.
+
+3. Request to be added to the drm/ci-ok group so that your user has the
+necessary privileges to run the CI on https://gitlab.freedesktop.org/drm/ci-ok
+
+4. Next time you push to this repository, you will see a CI pipeline being
+created (eg. https://gitlab.freedesktop.org/janedoe/linux/-/pipelines)
+
+5. The various jobs will be run and when the pipeline is finished, all jobs
+should be green unless a regression has been found.
+
+6. Warnings in the pipeline indicate that lockdep
+(see Documentation/locking/lockdep-design.rst) issues have been detected
+during the tests.
+
+
+How to update test expectations
+===============================
+
+If your changes to the code fix any tests, you will have to remove one or more
+lines from one or more of the files in
+drivers/gpu/drm/ci/${DRIVER_NAME}_*_fails.txt, for each of the test platforms
+affected by the change.
+
+
+How to expand coverage
+======================
+
+If your code changes make it possible to run more tests (by solving reliability
+issues, for example), you can remove tests from the flakes and/or skips lists,
+and then the expected results if there are any known failures.
+
+If there is a need for updating the version of IGT being used (maybe you have
+added more tests to it), update the IGT_VERSION variable at the top of the
+gitlab-ci.yml file.
+
+
+How to test your changes to the scripts
+=======================================
+
+For testing changes to the scripts in the drm-ci repo, change the
+DRM_CI_PROJECT_PATH and DRM_CI_COMMIT_SHA variables in
+drivers/gpu/drm/ci/gitlab-ci.yml to match your fork of the project (eg.
+janedoe/drm-ci). This fork needs to be in https://gitlab.freedesktop.org/.
+
+
+How to incorporate external fixes in your testing
+=================================================
+
+Often, regressions in other trees will prevent testing changes local to the
+tree under test. These fixes will be automatically merged in during the build
+jobs from a branch in the target tree that is named as
+${TARGET_BRANCH}-external-fixes.
+
+If the pipeline is not in a merge request and a branch with the same name
+exists in the local tree, commits from that branch will be merged in as well.
+
+
+How to deal with automated testing labs that may be down
+========================================================
+
+If a hardware farm is down and thus causing pipelines to fail that would
+otherwise pass, one can disable all jobs that would be submitted to that farm
+by editing the file at
+https://gitlab.freedesktop.org/gfx-ci/lab-status/-/blob/main/lab-status.yml.