[PATCH v2] RDMA/hns: drop dead empty check in setup_root_hem()

[Maoyi Xie]

setup_root_hem() reads the first entry of head->root and checks
the returned pointer against NULL:

    root_hem = list_first_entry(&head->root,
                                struct hns_roce_hem_item, list);
    if (!root_hem)
        return -ENOMEM;

list_first_entry() never returns NULL. On an empty list it returns
container_of(head, ..., list), a non-NULL garbage pointer that
aliases the head. So the check is dead.

The only caller adds an entry to head.root right before invoking
setup_root_hem():

    list_add(&root_hem->list, &head.root);
    ret = setup_root_hem(..., &head, ...);

So head.root is guaranteed non-empty on entry. Drop the check.

Suggested-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
Signed-off-by: Maoyi Xie <maoyixie.tju@xxxxxxxxx>
---
v2: drop the check entirely per Jason's review, instead of
    converting to list_first_entry_or_null() as in v1.
v1: https://lore.kernel.org/r/20260521132045.3430906-1-maoyixie.tju@xxxxxxxxx

 drivers/infiniband/hw/hns/hns_roce_hem.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/drivers/infiniband/hw/hns/hns_roce_hem.c b/drivers/infiniband/hw/hns/hns_roce_hem.c
index e7c9e30ad2d8..61cd9f96423e 100644
--- a/drivers/infiniband/hw/hns/hns_roce_hem.c
+++ b/drivers/infiniband/hw/hns/hns_roce_hem.c
@@ -1269,8 +1269,6 @@ setup_root_hem(struct hns_roce_dev *hr_dev, struct hns_roce_hem_list *hem_list,
 
 	root_hem = list_first_entry(&head->root,
 				    struct hns_roce_hem_item, list);
-	if (!root_hem)
-		return -ENOMEM;
 
 	total = 0;
 	for (i = 0; i < region_cnt && total <= max_ba_num; i++) {
-- 
2.34.1