From: Chia-I Wu <olvaffe@xxxxxxxxx> [ Upstream commit efe2bf965522bf0796d413b47a2abbf81d471d6f ] This is motivated by having meaningful ftrace events, but it also fixes use cases where dma_fence_is_later is called, such as in sync_file_merge. In other drivers, fence creation and cmdbuf submission normally happen atomically, mutex_lock(); fence = dma_fence_create(..., ++timeline->seqno); submit_cmdbuf(); mutex_unlock(); and have no such issue. But in our driver, because most ioctls queue commands into ctrlq, we do not want to grab a lock. Instead, we set seqno to 0 when a fence is created, and update it when the command is finally queued and the seqno is known. Signed-off-by: Chia-I Wu <olvaffe@xxxxxxxxx> Reviewed-by: Emil Velikov <emil.velikov@xxxxxxxxxxxxx> Link: http://patchwork.freedesktop.org/patch/msgid/20190429220825.156644-1-olvaffe@xxxxxxxxx Signed-off-by: Gerd Hoffmann <kraxel@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- drivers/gpu/drm/virtio/virtgpu_drv.h | 1 - drivers/gpu/drm/virtio/virtgpu_fence.c | 17 ++++++++++------- 2 files changed, 10 insertions(+), 8 deletions(-) diff --git a/drivers/gpu/drm/virtio/virtgpu_drv.h b/drivers/gpu/drm/virtio/virtgpu_drv.h index b69ae10ca238..d724fb3de44e 100644 --- a/drivers/gpu/drm/virtio/virtgpu_drv.h +++ b/drivers/gpu/drm/virtio/virtgpu_drv.h @@ -102,7 +102,6 @@ struct virtio_gpu_fence { struct dma_fence f; struct virtio_gpu_fence_driver *drv; struct list_head node; - uint64_t seq; }; #define to_virtio_fence(x) \ container_of(x, struct virtio_gpu_fence, f) diff --git a/drivers/gpu/drm/virtio/virtgpu_fence.c b/drivers/gpu/drm/virtio/virtgpu_fence.c index 87d1966192f4..72b4f7561432 100644 --- a/drivers/gpu/drm/virtio/virtgpu_fence.c +++ b/drivers/gpu/drm/virtio/virtgpu_fence.c @@ -40,16 +40,14 @@ bool virtio_fence_signaled(struct dma_fence *f) { struct virtio_gpu_fence *fence = to_virtio_fence(f); - if (atomic64_read(&fence->drv->last_seq) >= fence->seq) + if (atomic64_read(&fence->drv->last_seq) >= fence->f.seqno) return true; return false; } static void virtio_fence_value_str(struct dma_fence *f, char *str, int size) { - struct virtio_gpu_fence *fence = to_virtio_fence(f); - - snprintf(str, size, "%llu", fence->seq); + snprintf(str, size, "%llu", f->seqno); } static void virtio_timeline_value_str(struct dma_fence *f, char *str, int size) @@ -76,6 +74,11 @@ struct virtio_gpu_fence *virtio_gpu_fence_alloc(struct virtio_gpu_device *vgdev) return fence; fence->drv = drv; + + /* This only partially initializes the fence because the seqno is + * unknown yet. The fence must not be used outside of the driver + * until virtio_gpu_fence_emit is called. + */ dma_fence_init(&fence->f, &virtio_fence_ops, &drv->lock, drv->context, 0); return fence; @@ -89,13 +92,13 @@ int virtio_gpu_fence_emit(struct virtio_gpu_device *vgdev, unsigned long irq_flags; spin_lock_irqsave(&drv->lock, irq_flags); - fence->seq = ++drv->sync_seq; + fence->f.seqno = ++drv->sync_seq; dma_fence_get(&fence->f); list_add_tail(&fence->node, &drv->fences); spin_unlock_irqrestore(&drv->lock, irq_flags); cmd_hdr->flags |= cpu_to_le32(VIRTIO_GPU_FLAG_FENCE); - cmd_hdr->fence_id = cpu_to_le64(fence->seq); + cmd_hdr->fence_id = cpu_to_le64(fence->f.seqno); return 0; } @@ -109,7 +112,7 @@ void virtio_gpu_fence_event_process(struct virtio_gpu_device *vgdev, spin_lock_irqsave(&drv->lock, irq_flags); atomic64_set(&vgdev->fence_drv.last_seq, last_seq); list_for_each_entry_safe(fence, tmp, &drv->fences, node) { - if (last_seq < fence->seq) + if (last_seq < fence->f.seqno) continue; dma_fence_signal_locked(&fence->f); list_del(&fence->node); -- 2.20.1
