[PATCH v2] drm/amdkfd: Confirm list is non-empty before utilizing list_first_entry in kfd_topology.c

[Srinivasan Shanmugam]

Before using list_first_entry, make sure to check that list is not
empty, if list is empty return -ENODATA.

Fixes the below:
drivers/gpu/drm/amd/amdgpu/../amdkfd/kfd_topology.c:1347 kfd_create_indirect_link_prop() warn: can 'gpu_link' even be NULL?
drivers/gpu/drm/amd/amdgpu/../amdkfd/kfd_topology.c:1428 kfd_add_peer_prop() warn: can 'iolink1' even be NULL?
drivers/gpu/drm/amd/amdgpu/../amdkfd/kfd_topology.c:1433 kfd_add_peer_prop() warn: can 'iolink2' even be NULL?

'Fixes: 0f28cca87e9a ("drm/amdkfd: Extend KFD device topology to surface
peer-to-peer links")'
Suggested-by: Lijo Lazar <lijo.lazar at amd.com>
Suggested-by: Felix Kuehling <Felix.Kuehling at amd.com>
Cc: Felix Kuehling <Felix.Kuehling at amd.com>
Cc: Christian König <christian.koenig at amd.com>
Cc: Alex Deucher <alexander.deucher at amd.com>
Signed-off-by: Srinivasan Shanmugam <srinivasan.shanmugam at amd.com>
---

v2: 
  Changed to "if (list_empty(&kdev->io_link_props)) return -ENODATA;"
(Lijo)

 drivers/gpu/drm/amd/amdkfd/kfd_topology.c | 21 ++++++++++++---------
 1 file changed, 12 insertions(+), 9 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_topology.c b/drivers/gpu/drm/amd/amdkfd/kfd_topology.c
index dc7c8312e8c7..1fc9d4616564 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_topology.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_topology.c
@@ -1342,10 +1342,11 @@ static int kfd_create_indirect_link_prop(struct kfd_topology_device *kdev, int g
 		num_cpu++;
 	}
 
+	if (list_empty(&kdev->io_link_props))
+		return -ENODATA;
+
 	gpu_link = list_first_entry(&kdev->io_link_props,
-					struct kfd_iolink_properties, list);
-	if (!gpu_link)
-		return -ENOMEM;
+				    struct kfd_iolink_properties, list);
 
 	for (i = 0; i < num_cpu; i++) {
 		/* CPU <--> GPU */
@@ -1423,15 +1424,17 @@ static int kfd_add_peer_prop(struct kfd_topology_device *kdev,
 				peer->gpu->adev))
 		return ret;
 
+	if (list_empty(&kdev->io_link_props))
+		return -ENODATA;
+
 	iolink1 = list_first_entry(&kdev->io_link_props,
-							struct kfd_iolink_properties, list);
-	if (!iolink1)
-		return -ENOMEM;
+				   struct kfd_iolink_properties, list);
+
+	if (list_empty(&peer->io_link_props))
+		return -ENODATA;
 
 	iolink2 = list_first_entry(&peer->io_link_props,
-							struct kfd_iolink_properties, list);
-	if (!iolink2)
-		return -ENOMEM;
+				   struct kfd_iolink_properties, list);
 
 	props = kfd_alloc_struct(props);
 	if (!props)
-- 
2.34.1