drm_hwcomposer: Add check to vsync routine to avoid crash on callback

Vsync could be disabled during routine being running and this could
potentially lead to crash on callback invocation. Crash happens if
VSyncControl(false) was called when Routine has cached callback and
unlocked mutex but haven't callback yet. At this point we can't be
sure that callback is still valid so invoking it is incorrect
behaviour.

Second check if vsync is enabled drastically shortens window when we
could go into invalid state, from the whole vblank invocation to
several machine instructions between check and invocation.

Please note that we can't check against cached value in this case,
therefore operations on this flag should be atomic instead.

Signed-off-by: Roman Kovalivskyi <roman.kovalivskyi@globallogic.com>
2 files changed
tree: 39f577ee81a8a875ce83ef0474f5b482ebb0ea15
  1. compositor/
  2. drm/
  3. include/
  4. platform/
  5. tests/
  6. utils/
  7. .clang-format
  8. .gitlab-ci-checkcommit.sh
  9. .gitlab-ci.yml
  10. Android.bp
  11. drmhwctwo.cpp
  12. MODULE_LICENSE_APACHE2
  13. NOTICE
  14. README.md
README.md

drm_hwcomposer

Patches to drm_hwcomposer are very much welcome, we really want this to be the universal HW composer implementation for Android and similar platforms So please bring on porting patches, bugfixes, improvements for documentation and new features.

A short list of contribution guidelines:

  • Submit changes via gitlab merge requests on gitlab.freedesktop.org

  • drm_hwcomposer is Apache 2.0 Licensed and we require contributions to follow the developer's certificate of origin: http://developercertificate.org/

  • When submitting new code please follow the naming conventions documented in the generated documentation. Also please make full use of all the helpers and convenience macros provided by drm_hwcomposer. The below command can help you with formatting of your patches:

    `git diff | clang-format-diff-5.0 -p 1 -style=file`
    
  • Hardware specific changes should be tested on relevant platforms before committing.

If you need inspiration, please checkout our TODO issues

Happy hacking!