When reprioritising a request, we build a list of its dependencies in topological order. This should leave our origin request as the first element in our list, if it moves we have a dependency cycle and severe breakage. Assert that it doesn't move. Complete, but expensive checking is done by swfence, this assert is more about documenting the topologically ordered list. Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> Cc: Michał Winiarski <michal.winiarski@xxxxxxxxx> --- drivers/gpu/drm/i915/intel_lrc.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c index 4e150b095a11..42705e3875cd 100644 --- a/drivers/gpu/drm/i915/intel_lrc.c +++ b/drivers/gpu/drm/i915/intel_lrc.c @@ -1050,6 +1050,13 @@ static void execlists_schedule(struct drm_i915_gem_request *request, int prio) } } + /* + * We should never have a dep cycle back to ourselves, leaving + * the original request as the origin of our topologically sorted + * list. + */ + GEM_BUG_ON(list_first_entry(&dfs, typeof(stack), dfs_link) != &stack); + /* * If we didn't need to bump any existing priorities, and we haven't * yet submitted this request (i.e. there is no potential race with -- 2.15.1 _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
