[PATCH] drm/amdgpu: Unpin MMIO and DOORBELL BOs only after map count goes to zero

[Ramesh Errabolu]

In existing code MMIO and DOORBELL BOs are unpinned without ensuring the
condition that their map count has reached zero. Unpinning without checking
this constraint could lead to an error while BO is being freed. The patch
fixes this issue.

Signed-off-by: Ramesh Errabolu <Ramesh.Errabolu at amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c | 15 +++++++--------
 1 file changed, 7 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
index a1de900ba677..e5dc94b745b1 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
@@ -1832,13 +1832,6 @@ int amdgpu_amdkfd_gpuvm_free_memory_of_gpu(
 
 	mutex_lock(&mem->lock);
 
-	/* Unpin MMIO/DOORBELL BO's that were pinned during allocation */
-	if (mem->alloc_flags &
-	    (KFD_IOC_ALLOC_MEM_FLAGS_DOORBELL |
-	     KFD_IOC_ALLOC_MEM_FLAGS_MMIO_REMAP)) {
-		amdgpu_amdkfd_gpuvm_unpin_bo(mem->bo);
-	}
-
 	mapped_to_gpu_memory = mem->mapped_to_gpu_memory;
 	is_imported = mem->is_imported;
 	mutex_unlock(&mem->lock);
@@ -1855,7 +1848,7 @@ int amdgpu_amdkfd_gpuvm_free_memory_of_gpu(
 	/* Make sure restore workers don't access the BO any more */
 	bo_list_entry = &mem->validate_list;
 	mutex_lock(&process_info->lock);
-	list_del(&bo_list_entry->head);
+	list_del_init(&bo_list_entry->head);
 	mutex_unlock(&process_info->lock);
 
 	/* No more MMU notifiers */
@@ -1880,6 +1873,12 @@ int amdgpu_amdkfd_gpuvm_free_memory_of_gpu(
 
 	ret = unreserve_bo_and_vms(&ctx, false, false);
 
+	/* Unpin MMIO/DOORBELL BO's that were pinned during allocation */
+	if (mem->alloc_flags &
+	    (KFD_IOC_ALLOC_MEM_FLAGS_DOORBELL |
+	     KFD_IOC_ALLOC_MEM_FLAGS_MMIO_REMAP))
+		amdgpu_amdkfd_gpuvm_unpin_bo(mem->bo);
+
 	/* Free the sync object */
 	amdgpu_sync_free(&mem->sync);
 
-- 
2.35.1