diff options
| author | Chris Wilson <chris@chris-wilson.co.uk> | 2018-01-02 15:12:26 +0000 |
|---|---|---|
| committer | Chris Wilson <chris@chris-wilson.co.uk> | 2018-01-03 12:09:44 +0000 |
| commit | ce01b173773a09e2b5d3007c26d11cbd7737c3fe (patch) | |
| tree | 5a7eea6692e33197ee8d0b0612504f8613f01516 /drivers/gpu/drm/i915/intel_lrc.c | |
| parent | 83cc84c5a848748d4bb190bc179a7620491a925f (diff) | |
drm/i915/execlists: Assert there are no simple cycles in the dependencies
The dependency chain must be an acyclic graph. This is checked by the
swfence, but for sanity, also do a simple check that we do not corrupt
our list iteration in execlists_schedule() by a shallow dependency
cycle.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Michał Winiarski <michal.winiarski@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180102151235.3949-10-chris@chris-wilson.co.uk
Diffstat (limited to 'drivers/gpu/drm/i915/intel_lrc.c')
| -rw-r--r-- | drivers/gpu/drm/i915/intel_lrc.c | 11 |
1 files changed, 8 insertions, 3 deletions
diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c index 04c35e4dd7c6..7d1ce21fa051 100644 --- a/drivers/gpu/drm/i915/intel_lrc.c +++ b/drivers/gpu/drm/i915/intel_lrc.c @@ -1011,7 +1011,8 @@ static void execlists_schedule(struct drm_i915_gem_request *request, int prio) stack.signaler = &request->priotree; list_add(&stack.dfs_link, &dfs); - /* Recursively bump all dependent priorities to match the new request. + /* + * Recursively bump all dependent priorities to match the new request. * * A naive approach would be to use recursion: * static void update_priorities(struct i915_priotree *pt, prio) { @@ -1031,12 +1032,15 @@ static void execlists_schedule(struct drm_i915_gem_request *request, int prio) list_for_each_entry_safe(dep, p, &dfs, dfs_link) { struct i915_priotree *pt = dep->signaler; - /* Within an engine, there can be no cycle, but we may + /* + * Within an engine, there can be no cycle, but we may * refer to the same dependency chain multiple times * (redundant dependencies are not eliminated) and across * engines. */ list_for_each_entry(p, &pt->signalers_list, signal_link) { + GEM_BUG_ON(p == dep); /* no cycles! */ + if (i915_priotree_signaled(p->signaler)) continue; @@ -1048,7 +1052,8 @@ static void execlists_schedule(struct drm_i915_gem_request *request, int prio) list_safe_reset_next(dep, p, dfs_link); } - /* If we didn't need to bump any existing priorities, and we haven't + /* + * 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 * execlists_submit_request()), we can set our own priority and skip * acquiring the engine locks. |