drm/msm: make sure last_fence is always updated

Update last_fence in the vm-bind path instead of kernel managed path.

last_fence is used to wait for work to finish in vm_bind contexts but not
used for kernel managed contexts.

This fixes a bug where last_fence is not waited on context close leading
to faults as resources are freed while in use.

Fixes: 92395af ("drm/msm: Add VM_BIND submitqueue")
Signed-off-by: Anna Maniscalco <anna.maniscalco2000@gmail.com>
Patchwork: https://patchwork.freedesktop.org/patch/680080/
Message-ID: <20251011-close_fence_wait_fix-v3-1-5134787755ff@gmail.com>
Signed-off-by: Rob Clark <robin.clark@oss.qualcomm.com>

Author: Anna Maniscalco

drivers/gpu/drm/msm/msm_gem_submit.c

@@ -414,6 +414,11 @@ static void submit_attach_object_fences(struct msm_gem_submit *submit)
 					 submit->user_fence,
 					 DMA_RESV_USAGE_BOOKKEEP,
 					 DMA_RESV_USAGE_BOOKKEEP);
+
+		last_fence = vm->last_fence;
+		vm->last_fence = dma_fence_unwrap_merge(submit->user_fence, last_fence);
+		dma_fence_put(last_fence);
+
 		return;
 	}
 
@@ -427,10 +432,6 @@ static void submit_attach_object_fences(struct msm_gem_submit *submit)
 			dma_resv_add_fence(obj->resv, submit->user_fence,
 					   DMA_RESV_USAGE_READ);
 	}
-
-	last_fence = vm->last_fence;
-	vm->last_fence = dma_fence_unwrap_merge(submit->user_fence, last_fence);
-	dma_fence_put(last_fence);
 }
 
 static int submit_bo(struct msm_gem_submit *submit, uint32_t idx,