From 4a50d20e105a4a8e46a641e4779e9431e0aabc84 Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Tue, 26 Jul 2016 12:01:50 +0100 Subject: [PATCH] drm/i915: Reduce breadcrumb lock coverage for intel_engine_enable_signaling() Since intel_engine_enable_signaling() is now only called via fence_enable_sw_signaling(), we can rely on it to provide serialisation and run-once for us and so make ourselves slightly simpler. Signed-off-by: Chris Wilson Link: http://patchwork.freedesktop.org/patch/msgid/1469432687-22756-2-git-send-email-chris@chris-wilson.co.uk Cc: Tvrtko Ursulin Reviewed-by: Joonas Lahtinen Link: http://patchwork.freedesktop.org/patch/msgid/1469530913-17180-1-git-send-email-chris@chris-wilson.co.uk --- drivers/gpu/drm/i915/intel_breadcrumbs.c | 13 ++++--------- 1 file changed, 4 insertions(+), 9 deletions(-) diff --git a/drivers/gpu/drm/i915/intel_breadcrumbs.c b/drivers/gpu/drm/i915/intel_breadcrumbs.c index d893ccd..9086744 100644 --- a/drivers/gpu/drm/i915/intel_breadcrumbs.c +++ b/drivers/gpu/drm/i915/intel_breadcrumbs.c @@ -480,19 +480,15 @@ void intel_engine_enable_signaling(struct drm_i915_gem_request *request) struct rb_node *parent, **p; bool first, wakeup; - if (unlikely(READ_ONCE(request->signaling.wait.tsk))) - return; - - spin_lock(&b->lock); - if (unlikely(request->signaling.wait.tsk)) { - wakeup = false; - goto unlock; - } + /* locked by fence_enable_sw_signaling() */ + assert_spin_locked(&request->lock); request->signaling.wait.tsk = b->signaler; request->signaling.wait.seqno = request->fence.seqno; i915_gem_request_get(request); + spin_lock(&b->lock); + /* First add ourselves into the list of waiters, but register our * bottom-half as the signaller thread. As per usual, only the oldest * waiter (not just signaller) is tasked as the bottom-half waking @@ -525,7 +521,6 @@ void intel_engine_enable_signaling(struct drm_i915_gem_request *request) if (first) smp_store_mb(b->first_signal, request); -unlock: spin_unlock(&b->lock); if (wakeup) -- 2.7.4