[PATCH 2/2] drm/msm: Restore error return on invalid fence

[Rob Clark <robdclark@gmail.com>]

From: Rob Clark <robdclark@chromium.org>

When converting to use an idr to map userspace fence seqno values back
to a dma_fence, we lost the error return when userspace passes seqno
that is larger than the last submitted fence.  Restore this check.

Reported-by: Akhil P Oommen <akhilpo@codeaurora.org>
Fixes: a61acbbe9cf8 ("drm/msm: Track "seqno" fences by idr")
Signed-off-by: Rob Clark <robdclark@chromium.org>
---
Note: I will rebase "drm/msm: Handle fence rollover" on top of this,
to simplify backporting this patch to stable kernels

 drivers/gpu/drm/msm/msm_drv.c        | 6 ++++++
 drivers/gpu/drm/msm/msm_gem_submit.c | 1 +
 drivers/gpu/drm/msm/msm_gpu.h        | 3 +++
 3 files changed, 10 insertions(+)

diff --git a/drivers/gpu/drm/msm/msm_drv.c b/drivers/gpu/drm/msm/msm_drv.c
index cb14d997c174..56500eb5219e 100644
--- a/drivers/gpu/drm/msm/msm_drv.c
+++ b/drivers/gpu/drm/msm/msm_drv.c
@@ -967,6 +967,12 @@ static int wait_fence(struct msm_gpu_submitqueue *queue, uint32_t fence_id,
 	struct dma_fence *fence;
 	int ret;
 
+	if (fence_id > queue->last_fence) {
+		DRM_ERROR_RATELIMITED("waiting on invalid fence: %u (of %u)\n",
+				      fence_id, queue->last_fence);
+		return -EINVAL;
+	}
+
 	/*
 	 * Map submitqueue scoped "seqno" (which is actually an idr key)
 	 * back to underlying dma-fence
diff --git a/drivers/gpu/drm/msm/msm_gem_submit.c b/drivers/gpu/drm/msm/msm_gem_submit.c
index 151d19e4453c..a38f23be497d 100644
--- a/drivers/gpu/drm/msm/msm_gem_submit.c
+++ b/drivers/gpu/drm/msm/msm_gem_submit.c
@@ -911,6 +911,7 @@ int msm_ioctl_gem_submit(struct drm_device *dev, void *data,
 	drm_sched_entity_push_job(&submit->base, queue->entity);
 
 	args->fence = submit->fence_id;
+	queue->last_fence = submit->fence_id;
 
 	msm_reset_syncobjs(syncobjs_to_reset, args->nr_in_syncobjs);
 	msm_process_post_deps(post_deps, args->nr_out_syncobjs,
diff --git a/drivers/gpu/drm/msm/msm_gpu.h b/drivers/gpu/drm/msm/msm_gpu.h
index bd4e0024033e..e73a5bb03544 100644
--- a/drivers/gpu/drm/msm/msm_gpu.h
+++ b/drivers/gpu/drm/msm/msm_gpu.h
@@ -376,6 +376,8 @@ static inline int msm_gpu_convert_priority(struct msm_gpu *gpu, int prio,
  * @ring_nr:   the ringbuffer used by this submitqueue, which is determined
  *             by the submitqueue's priority
  * @faults:    the number of GPU hangs associated with this submitqueue
+ * @last_fence: the sequence number of the last allocated fence (for error
+ *             checking)
  * @ctx:       the per-drm_file context associated with the submitqueue (ie.
  *             which set of pgtables do submits jobs associated with the
  *             submitqueue use)
@@ -391,6 +393,7 @@ struct msm_gpu_submitqueue {
 	u32 flags;
 	u32 ring_nr;
 	int faults;
+	uint32_t last_fence;
 	struct msm_file_private *ctx;
 	struct list_head node;
 	struct idr fence_idr;
-- 
2.31.1