Op 30-07-18 om 07:18 schreef Satendra Singh Thakur:

1. Currently, if modeset_lock is re-tried many times in case of EDEADLK

error, then this will be the code flow

retry: ret = drm_modeset_lock();

if (ret)-->this is true goto out;

out: if (fb) if (plane->old_fb) if (ret == -EDEADLK) goto retry; It can be observed that checks on fb, old_fb are redundant in retry-case. If we keep if (ret == -EDEADLK) right after the out label, that will avoid redundant checks. It won't affect normal scenario (non-retry case). 2. Moved NULL assignment inside if statement related to NULL check

Signed-off-by: Satendra Singh Thakur satendra.t@samsung.com

drivers/gpu/drm/drm_plane.c | 17 +++++++++-------- 1 file changed, 9 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/drm_plane.c b/drivers/gpu/drm/drm_plane.c index 0350544..ed42cd4 100644 --- a/drivers/gpu/drm/drm_plane.c +++ b/drivers/gpu/drm/drm_plane.c @@ -658,9 +658,10 @@ static int __setplane_internal(struct drm_plane *plane, }

out:

• if (plane->old_fb)

• if (plane->old_fb) { drm_framebuffer_put(plane->old_fb);

• plane->old_fb = NULL;

• plane->old_fb = NULL;
  

• }

  return ret;

} @@ -1097,17 +1098,17 @@ int drm_mode_page_flip_ioctl(struct drm_device *dev, }

out:

• if (fb)

• drm_framebuffer_put(fb);
  

• if (plane->old_fb)

• drm_framebuffer_put(plane->old_fb);
  

• plane->old_fb = NULL;
• if (ret == -EDEADLK) { ret = drm_modeset_backoff(&ctx); if (!ret) goto retry; }

• if (fb)

• drm_framebuffer_put(fb);
  

• if (plane->old_fb) {

• drm_framebuffer_put(plane->old_fb);
  

• plane->old_fb = NULL;
  

• }

  drm_modeset_drop_locks(&ctx); drm_modeset_acquire_fini(&ctx);

It's not redundant. plane->old_fb is protected by the plane_mutex lock and should be null before dropping the locks in drm_modeset_backoff(). Else other code will trip with a WARN_ON(plane->old_fb != NULL);

Before sending any more patches I would strongly suggest setting CONFIG_DEBUG_WW_MUTEX_SLOWPATH and CONFIG_PROVE_LOCKING in your kernel, and try to run the IGT testsuite.

~Maarten