Revert "nouveau: push event block/allowing out of the fence context"

This reverts commit eacabb54.

This commit causes some regressions in desktop usage, this will
reintroduce the original deadlock in DRI_PRIME situations, I've
got an idea to fix it by offloading to a workqueue in a different
spot, however this code has a race condition where we sometimes
miss interrupts so I'd like to fix that as well.

Cc: stable@vger.kernel.org
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/nouveau/nouveau_fence.c

@@ -62,7 +62,7 @@ nouveau_fence_signal(struct nouveau_fence *fence)
 	if (test_bit(DMA_FENCE_FLAG_USER_BITS, &fence->base.flags)) {
 		struct nouveau_fence_chan *fctx = nouveau_fctx(fence);
 
-		if (atomic_dec_and_test(&fctx->notify_ref))
+		if (!--fctx->notify_ref)
 			drop = 1;
 	}
 
@@ -103,7 +103,6 @@ nouveau_fence_context_kill(struct nouveau_fence_chan *fctx, int error)
 void
 nouveau_fence_context_del(struct nouveau_fence_chan *fctx)
 {
-	cancel_work_sync(&fctx->allow_block_work);
 	nouveau_fence_context_kill(fctx, 0);
 	nvif_event_dtor(&fctx->event);
 	fctx->dead = 1;
@@ -168,18 +167,6 @@ nouveau_fence_wait_uevent_handler(struct nvif_event *event, void *repv, u32 repc
 	return ret;
 }
 
-static void
-nouveau_fence_work_allow_block(struct work_struct *work)
-{
-	struct nouveau_fence_chan *fctx = container_of(work, struct nouveau_fence_chan,
-						       allow_block_work);
-
-	if (atomic_read(&fctx->notify_ref) == 0)
-		nvif_event_block(&fctx->event);
-	else
-		nvif_event_allow(&fctx->event);
-}
-
 void
 nouveau_fence_context_new(struct nouveau_channel *chan, struct nouveau_fence_chan *fctx)
 {
@@ -191,7 +178,6 @@ nouveau_fence_context_new(struct nouveau_channel *chan, struct nouveau_fence_cha
 	} args;
 	int ret;
 
-	INIT_WORK(&fctx->allow_block_work, nouveau_fence_work_allow_block);
 	INIT_LIST_HEAD(&fctx->flip);
 	INIT_LIST_HEAD(&fctx->pending);
 	spin_lock_init(&fctx->lock);
@@ -535,19 +521,15 @@ static bool nouveau_fence_enable_signaling(struct dma_fence *f)
 	struct nouveau_fence *fence = from_fence(f);
 	struct nouveau_fence_chan *fctx = nouveau_fctx(fence);
 	bool ret;
-	bool do_work;
 
-	if (atomic_inc_return(&fctx->notify_ref) == 0)
-		do_work = true;
+	if (!fctx->notify_ref++)
+		nvif_event_allow(&fctx->event);
 
 	ret = nouveau_fence_no_signaling(f);
 	if (ret)
 		set_bit(DMA_FENCE_FLAG_USER_BITS, &fence->base.flags);
-	else if (atomic_dec_and_test(&fctx->notify_ref))
-		do_work = true;
-
-	if (do_work)
-		schedule_work(&fctx->allow_block_work);
+	else if (!--fctx->notify_ref)
+		nvif_event_block(&fctx->event);
 
 	return ret;
 }

drivers/gpu/drm/nouveau/nouveau_fence.h

@@ -3,7 +3,6 @@
 #define __NOUVEAU_FENCE_H__
 
 #include <linux/dma-fence.h>
-#include <linux/workqueue.h>
 #include <nvif/event.h>
 
 struct nouveau_drm;
@@ -46,9 +45,7 @@ struct nouveau_fence_chan {
 	char name[32];
 
 	struct nvif_event event;
-	struct work_struct allow_block_work;
-	atomic_t notify_ref;
-	int dead, killed;
+	int notify_ref, dead, killed;
 };
 
 struct nouveau_fence_priv {