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See the following source code: > ------------------------------------------------------------------------------ > // kernel/bpf/hashtab.c > htab_map_update_elem { > ... > /* add new element to the head of the list, so that > * concurrent search will find it before old elem > */ > hlist_nulls_add_head_rcu(&l_new->hash_node, head); > ... > } > ------------------------------------------------------------------------------ > > Therefore, when I was trying to traversing the two elements in the same hash a bucket, it ran into an infinite loop by repeatedly getting the key of these two elements. Not sure my understanding for "bpf_map_update_elem"and "bpf_map_get_next_key" is correct or not. My question is: is that behave as the design? or is it a bug for the bpf hashmap? Please let me know, thanks. bpf_map_get_next_key() is added after bpf_map_update_elem(). So the above behavior is in the kernel already for sometimes. bpf_map_get_next_key() is not super reliable for hash table as if some deletion happens, the get_next_key may start from the beginning. The recommendation is to use bpf_map_*_batch() interface. If your kernel does not implement bpf_map_*_batch() interface, I think it would be best you call bpf_map_get_next_key() for ALL elements before doing any update/delete. > > Best regards > W.Gao >