From 27745e829a5cb896249f355f5bdab3249c5455e2 Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Wed, 16 Nov 2016 15:27:21 +0000 Subject: [PATCH] drm/i915/execlists: Use a local lock for dfs_link access Avoid requiring struct_mutex for exclusive access to the temporary dfs_link inside the i915_dependency as not all callers may want to touch struct_mutex. So rather than force them to take a highly contended lock, introduce a local lock for the execlists schedule operation. Reported-by: David Weinehall Fixes: 9a151987d709 ("drm/i915: Add execution priority boosting for mmioflips") Signed-off-by: Chris Wilson Cc: Tvrtko Ursulin Cc: David Weinehall Link: http://patchwork.freedesktop.org/patch/msgid/20161116152721.11053-1-chris@chris-wilson.co.uk Reviewed-by: Tvrtko Ursulin --- drivers/gpu/drm/i915/intel_lrc.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c index f50feaa7116a..43526814e042 100644 --- a/drivers/gpu/drm/i915/intel_lrc.c +++ b/drivers/gpu/drm/i915/intel_lrc.c @@ -694,6 +694,7 @@ pt_lock_engine(struct i915_priotree *pt, struct intel_engine_cs *locked) static void execlists_schedule(struct drm_i915_gem_request *request, int prio) { + static DEFINE_MUTEX(lock); struct intel_engine_cs *engine = NULL; struct i915_dependency *dep, *p; struct i915_dependency stack; @@ -702,8 +703,8 @@ static void execlists_schedule(struct drm_i915_gem_request *request, int prio) if (prio <= READ_ONCE(request->priotree.priority)) return; - /* Need BKL in order to use the temporary link inside i915_dependency */ - lockdep_assert_held(&request->i915->drm.struct_mutex); + /* Need global lock to use the temporary link inside i915_dependency */ + mutex_lock(&lock); stack.signaler = &request->priotree; list_add(&stack.dfs_link, &dfs); @@ -770,6 +771,8 @@ static void execlists_schedule(struct drm_i915_gem_request *request, int prio) if (engine) spin_unlock_irq(&engine->timeline->lock); + mutex_unlock(&lock); + /* XXX Do we need to preempt to make room for us and our deps? */ } -- GitLab