drm/i915/gt: Declare timeline.lock to be irq-free

Now that we never allow the intel_wakeref callbacks to be invoked from
interrupt context, we do not need the irqsafe spinlock for the timeline.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191120170858.3965380-1-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/gt/intel_gt_requests.c

@@ -33,7 +33,6 @@ long intel_gt_retire_requests_timeout(struct intel_gt *gt, long timeout)
 {
 	struct intel_gt_timelines *timelines = &gt->timelines;
 	struct intel_timeline *tl, *tn;
-	unsigned long flags;
 	bool interruptible;
 	LIST_HEAD(free);
 
@@ -43,15 +42,15 @@ long intel_gt_retire_requests_timeout(struct intel_gt *gt, long timeout)
 
 	flush_submission(gt); /* kick the ksoftirqd tasklets */
 
-	spin_lock_irqsave(&timelines->lock, flags);
+	spin_lock(&timelines->lock);
 	list_for_each_entry_safe(tl, tn, &timelines->active_list, link) {
 		if (!mutex_trylock(&tl->mutex))
 			continue;
 
 		intel_timeline_get(tl);
 		GEM_BUG_ON(!atomic_read(&tl->active_count));
 		atomic_inc(&tl->active_count); /* pin the list element */
-		spin_unlock_irqrestore(&timelines->lock, flags);
+		spin_unlock(&timelines->lock);
 
 		if (timeout > 0) {
 			struct dma_fence *fence;
@@ -67,7 +66,7 @@ long intel_gt_retire_requests_timeout(struct intel_gt *gt, long timeout)
 
 		retire_requests(tl);
 
-		spin_lock_irqsave(&timelines->lock, flags);
+		spin_lock(&timelines->lock);
 
 		/* Resume iteration after dropping lock */
 		list_safe_reset_next(tl, tn, link);
@@ -82,7 +81,7 @@ long intel_gt_retire_requests_timeout(struct intel_gt *gt, long timeout)
 			list_add(&tl->link, &free);
 		}
 	}
-	spin_unlock_irqrestore(&timelines->lock, flags);
+	spin_unlock(&timelines->lock);
 
 	list_for_each_entry_safe(tl, tn, &free, link)
 		__intel_timeline_free(&tl->kref);

drivers/gpu/drm/i915/gt/intel_reset.c

@@ -831,7 +831,6 @@ static bool __intel_gt_unset_wedged(struct intel_gt *gt)
 {
 	struct intel_gt_timelines *timelines = &gt->timelines;
 	struct intel_timeline *tl;
-	unsigned long flags;
 	bool ok;
 
 	if (!test_bit(I915_WEDGED, &gt->reset.flags))
@@ -853,15 +852,15 @@ static bool __intel_gt_unset_wedged(struct intel_gt *gt)
 	 *
 	 * No more can be submitted until we reset the wedged bit.
 	 */
-	spin_lock_irqsave(&timelines->lock, flags);
+	spin_lock(&timelines->lock);
 	list_for_each_entry(tl, &timelines->active_list, link) {
 		struct dma_fence *fence;
 
 		fence = i915_active_fence_get(&tl->last_request);
 		if (!fence)
 			continue;
 
-		spin_unlock_irqrestore(&timelines->lock, flags);
+		spin_unlock(&timelines->lock);
 
 		/*
 		 * All internal dependencies (i915_requests) will have
@@ -874,10 +873,10 @@ static bool __intel_gt_unset_wedged(struct intel_gt *gt)
 		dma_fence_put(fence);
 
 		/* Restart iteration after droping lock */
-		spin_lock_irqsave(&timelines->lock, flags);
+		spin_lock(&timelines->lock);
 		tl = list_entry(&timelines->active_list, typeof(*tl), link);
 	}
-	spin_unlock_irqrestore(&timelines->lock, flags);
+	spin_unlock(&timelines->lock);
 
 	/* We must reset pending GPU events before restoring our submission */
 	ok = !HAS_EXECLISTS(gt->i915); /* XXX better agnosticism desired */

drivers/gpu/drm/i915/gt/intel_timeline.c

@@ -332,7 +332,6 @@ int intel_timeline_pin(struct intel_timeline *tl)
 void intel_timeline_enter(struct intel_timeline *tl)
 {
 	struct intel_gt_timelines *timelines = &tl->gt->timelines;
-	unsigned long flags;
 
 	/*
 	 * Pretend we are serialised by the timeline->mutex.
@@ -358,16 +357,15 @@ void intel_timeline_enter(struct intel_timeline *tl)
 	if (atomic_add_unless(&tl->active_count, 1, 0))
 		return;
 
-	spin_lock_irqsave(&timelines->lock, flags);
+	spin_lock(&timelines->lock);
 	if (!atomic_fetch_inc(&tl->active_count))
 		list_add_tail(&tl->link, &timelines->active_list);
-	spin_unlock_irqrestore(&timelines->lock, flags);
+	spin_unlock(&timelines->lock);
 }
 
 void intel_timeline_exit(struct intel_timeline *tl)
 {
 	struct intel_gt_timelines *timelines = &tl->gt->timelines;
-	unsigned long flags;
 
 	/* See intel_timeline_enter() */
 	lockdep_assert_held(&tl->mutex);
@@ -376,10 +374,10 @@ void intel_timeline_exit(struct intel_timeline *tl)
 	if (atomic_add_unless(&tl->active_count, -1, 1))
 		return;
 
-	spin_lock_irqsave(&timelines->lock, flags);
+	spin_lock(&timelines->lock);
 	if (atomic_dec_and_test(&tl->active_count))
 		list_del(&tl->link);
-	spin_unlock_irqrestore(&timelines->lock, flags);
+	spin_unlock(&timelines->lock);
 
 	/*
 	 * Since this timeline is idle, all bariers upon which we were waiting