nouveau: rip out busy fence waits

I'm pretty sure this optimisation is actually not a great idea,
and is racy with other things waiting for fences.

Just nuke it, there should be no need to do fence waits in a
busy CPU loop.

Signed-off-by: Dave Airlie <airlied@redhat.com>
Reviewed-by: Ben Skeggs <bskeggs@nvidia.com>
Signed-off-by: Danilo Krummrich <dakr@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240417054032.3145721-1-airlied@gmail.com

drivers/gpu/drm/nouveau/nouveau_bo.c

@@ -898,7 +898,7 @@ nouveau_bo_move_m2mf(struct ttm_buffer_object *bo, int evict,
 	 * Without this the operation can timeout and we'll fallback to a
 	 * software copy, which might take several minutes to finish.
 	 */
-	nouveau_fence_wait(fence, false, false);
+	nouveau_fence_wait(fence, false);
 	ret = ttm_bo_move_accel_cleanup(bo, &fence->base, evict, false,
 					new_reg);
 	nouveau_fence_unref(&fence);

drivers/gpu/drm/nouveau/nouveau_chan.c

@@ -72,7 +72,7 @@ nouveau_channel_idle(struct nouveau_channel *chan)
 
 		ret = nouveau_fence_new(&fence, chan);
 		if (!ret) {
-			ret = nouveau_fence_wait(fence, false, false);
+			ret = nouveau_fence_wait(fence, false);
 			nouveau_fence_unref(&fence);
 		}
 

drivers/gpu/drm/nouveau/nouveau_dmem.c

@@ -128,7 +128,7 @@ static void nouveau_dmem_page_free(struct page *page)
 static void nouveau_dmem_fence_done(struct nouveau_fence **fence)
 {
 	if (fence) {
-		nouveau_fence_wait(*fence, true, false);
+		nouveau_fence_wait(*fence, false);
 		nouveau_fence_unref(fence);
 	} else {
 		/*

drivers/gpu/drm/nouveau/nouveau_fence.c

@@ -311,39 +311,11 @@ nouveau_fence_wait_legacy(struct dma_fence *f, bool intr, long wait)
 	return timeout - t;
 }
 
-static int
-nouveau_fence_wait_busy(struct nouveau_fence *fence, bool intr)
-{
-	int ret = 0;
-
-	while (!nouveau_fence_done(fence)) {
-		if (time_after_eq(jiffies, fence->timeout)) {
-			ret = -EBUSY;
-			break;
-		}
-
-		__set_current_state(intr ?
-				    TASK_INTERRUPTIBLE :
-				    TASK_UNINTERRUPTIBLE);
-
-		if (intr && signal_pending(current)) {
-			ret = -ERESTARTSYS;
-			break;
-		}
-	}
-
-	__set_current_state(TASK_RUNNING);
-	return ret;
-}
-
 int
-nouveau_fence_wait(struct nouveau_fence *fence, bool lazy, bool intr)
+nouveau_fence_wait(struct nouveau_fence *fence, bool intr)
 {
 	long ret;
 
-	if (!lazy)
-		return nouveau_fence_wait_busy(fence, intr);
-
 	ret = dma_fence_wait_timeout(&fence->base, intr, 15 * HZ);
 	if (ret < 0)
 		return ret;

drivers/gpu/drm/nouveau/nouveau_fence.h

@@ -23,7 +23,7 @@ void nouveau_fence_unref(struct nouveau_fence **);
 
 int  nouveau_fence_emit(struct nouveau_fence *);
 bool nouveau_fence_done(struct nouveau_fence *);
-int  nouveau_fence_wait(struct nouveau_fence *, bool lazy, bool intr);
+int  nouveau_fence_wait(struct nouveau_fence *, bool intr);
 int  nouveau_fence_sync(struct nouveau_bo *, struct nouveau_channel *, bool exclusive, bool intr);
 
 struct nouveau_fence_chan {

drivers/gpu/drm/nouveau/nouveau_gem.c

@@ -928,7 +928,7 @@ revalidate:
 	}
 
 	if (sync) {
-		if (!(ret = nouveau_fence_wait(fence, false, false))) {
+		if (!(ret = nouveau_fence_wait(fence, false))) {
 			if ((ret = dma_fence_get_status(&fence->base)) == 1)
 				ret = 0;
 		}