drm/msm: fix locking inconsistency for gpu->hw_init()

Most, but not all, paths where calling the with struct_mutex held.  The
fast-path in msm_gem_get_iova() (plus some sub-code-paths that only run
the first time) was masking this issue.

So lets just always hold struct_mutex for hw_init().  And sprinkle some
WARN_ON()'s and might_lock() to avoid this sort of problem in the
future.
Signed-off-by: Rob Clark <robdclark@gmail.com>

drivers/gpu/drm/msm/adreno/a5xx_gpu.c

@@ -297,31 +297,28 @@ static struct drm_gem_object *a5xx_ucode_load_bo(struct msm_gpu *gpu,
 	struct drm_gem_object *bo;
 	void *ptr;
 
-	mutex_lock(&drm->struct_mutex);
 	bo = msm_gem_new(drm, fw->size - 4, MSM_BO_UNCACHED);
-	mutex_unlock(&drm->struct_mutex);
-
 	if (IS_ERR(bo))
 		return bo;
 
-	ptr = msm_gem_get_vaddr(bo);
+	ptr = msm_gem_get_vaddr_locked(bo);
 	if (!ptr) {
-		drm_gem_object_unreference_unlocked(bo);
+		drm_gem_object_unreference(bo);
 		return ERR_PTR(-ENOMEM);
 	}
 
 	if (iova) {
-		int ret = msm_gem_get_iova(bo, gpu->id, iova);
+		int ret = msm_gem_get_iova_locked(bo, gpu->id, iova);
 
 		if (ret) {
-			drm_gem_object_unreference_unlocked(bo);
+			drm_gem_object_unreference(bo);
 			return ERR_PTR(ret);
 		}
 	}
 
 	memcpy(ptr, &fw->data[4], fw->size - 4);
 
-	msm_gem_put_vaddr(bo);
+	msm_gem_put_vaddr_locked(bo);
 	return bo;
 }
 

drivers/gpu/drm/msm/adreno/a5xx_power.c

@@ -294,17 +294,14 @@ void a5xx_gpmu_ucode_init(struct msm_gpu *gpu)
 	 */
 	bosize = (cmds_size + (cmds_size / TYPE4_MAX_PAYLOAD) + 1) << 2;
 
-	mutex_lock(&drm->struct_mutex);
 	a5xx_gpu->gpmu_bo = msm_gem_new(drm, bosize, MSM_BO_UNCACHED);
-	mutex_unlock(&drm->struct_mutex);
-
 	if (IS_ERR(a5xx_gpu->gpmu_bo))
 		goto err;
 
-	if (msm_gem_get_iova(a5xx_gpu->gpmu_bo, gpu->id, &a5xx_gpu->gpmu_iova))
+	if (msm_gem_get_iova_locked(a5xx_gpu->gpmu_bo, gpu->id, &a5xx_gpu->gpmu_iova))
 		goto err;
 
-	ptr = msm_gem_get_vaddr(a5xx_gpu->gpmu_bo);
+	ptr = msm_gem_get_vaddr_locked(a5xx_gpu->gpmu_bo);
 	if (!ptr)
 		goto err;
 
@@ -323,7 +320,7 @@ void a5xx_gpmu_ucode_init(struct msm_gpu *gpu)
 		cmds_size -= _size;
 	}
 
-	msm_gem_put_vaddr(a5xx_gpu->gpmu_bo);
+	msm_gem_put_vaddr_locked(a5xx_gpu->gpmu_bo);
 	a5xx_gpu->gpmu_dwords = dwords;
 
 	goto out;
@@ -332,7 +329,7 @@ void a5xx_gpmu_ucode_init(struct msm_gpu *gpu)
 	if (a5xx_gpu->gpmu_iova)
 		msm_gem_put_iova(a5xx_gpu->gpmu_bo, gpu->id);
 	if (a5xx_gpu->gpmu_bo)
-		drm_gem_object_unreference_unlocked(a5xx_gpu->gpmu_bo);
+		drm_gem_object_unreference(a5xx_gpu->gpmu_bo);
 
 	a5xx_gpu->gpmu_bo = NULL;
 	a5xx_gpu->gpmu_iova = 0;

drivers/gpu/drm/msm/adreno/adreno_device.c

@@ -159,7 +159,9 @@ struct msm_gpu *adreno_load_gpu(struct drm_device *dev)
 		int ret;
 
 		pm_runtime_get_sync(&pdev->dev);
+		mutex_lock(&dev->struct_mutex);
 		ret = msm_gpu_hw_init(gpu);
+		mutex_unlock(&dev->struct_mutex);
 		pm_runtime_put_sync(&pdev->dev);
 		if (ret) {
 			dev_err(dev->dev, "gpu hw init failed: %d\n", ret);

drivers/gpu/drm/msm/adreno/adreno_gpu.c

@@ -64,7 +64,7 @@ int adreno_hw_init(struct msm_gpu *gpu)
 
 	DBG("%s", gpu->name);
 
-	ret = msm_gem_get_iova(gpu->rb->bo, gpu->id, &gpu->rb_iova);
+	ret = msm_gem_get_iova_locked(gpu->rb->bo, gpu->id, &gpu->rb_iova);
 	if (ret) {
 		gpu->rb_iova = 0;
 		dev_err(gpu->dev->dev, "could not map ringbuffer: %d\n", ret);

drivers/gpu/drm/msm/msm_gem.c

@@ -314,6 +314,8 @@ int msm_gem_get_iova_locked(struct drm_gem_object *obj, int id,
 	struct msm_gem_object *msm_obj = to_msm_bo(obj);
 	int ret = 0;
 
+	WARN_ON(!mutex_is_locked(&obj->dev->struct_mutex));
+
 	if (!msm_obj->domain[id].iova) {
 		struct msm_drm_private *priv = obj->dev->dev_private;
 		struct page **pages = get_pages(obj);
@@ -345,6 +347,7 @@ int msm_gem_get_iova(struct drm_gem_object *obj, int id, uint64_t *iova)
 	 * bo is deleted:
 	 */
 	if (msm_obj->domain[id].iova) {
+		might_lock(&obj->dev->struct_mutex);
 		*iova = msm_obj->domain[id].iova;
 		return 0;
 	}

drivers/gpu/drm/msm/msm_gpu.c

@@ -203,6 +203,8 @@ int msm_gpu_hw_init(struct msm_gpu *gpu)
 {
 	int ret;
 
+	WARN_ON(!mutex_is_locked(&gpu->dev->struct_mutex));
+
 	if (!gpu->needs_hw_init)
 		return 0;