Re: [PATCH net-next] bpf: Remove unused but set variable in __bpf_lru_list_shrink_inactive()

[Alexei Starovoitov]

On Tue, Jan 10, 2017 at 03:02:07PM +0100, Tobias Klauser wrote:
> Remove the unused but set variable 'first_node' in
> __bpf_lru_list_shrink_inactive() to fix the following GCC warning when
> building with 'W=1':
> 
>   kernel/bpf/bpf_lru_list.c:216:41: warning: variable ‘first_node’ set but 
> not used [-Wunused-but-set-variable]
> 
> Cc: Martin KaFai Lau <ka...@fb.com>
> Signed-off-by: Tobias Klauser <tklau...@distanz.ch>
> ---
>  kernel/bpf/bpf_lru_list.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/kernel/bpf/bpf_lru_list.c b/kernel/bpf/bpf_lru_list.c
> index 89b7ef41c86b..d78501ee0609 100644
> --- a/kernel/bpf/bpf_lru_list.c
> +++ b/kernel/bpf/bpf_lru_list.c
> @@ -213,11 +213,10 @@ __bpf_lru_list_shrink_inactive(struct bpf_lru *lru,
>                              enum bpf_lru_list_type tgt_free_type)
>  {
>       struct list_head *inactive = &l->lists[BPF_LRU_LIST_T_INACTIVE];
> -     struct bpf_lru_node *node, *tmp_node, *first_node;
> +     struct bpf_lru_node *node, *tmp_node;
>       unsigned int nshrinked = 0;
>       unsigned int i = 0;
>  
> -     first_node = list_first_entry(inactive, struct bpf_lru_node, list);
>       list_for_each_entry_safe_reverse(node, tmp_node, inactive, list) {
>               if (bpf_lru_node_is_ref(node)) {
>                       __bpf_lru_node_move(l, node, BPF_LRU_LIST_T_ACTIVE);

Martin,
I cannot tell whether it's actually copy-paste leftover
or this patch is needed:

diff --git a/kernel/bpf/bpf_lru_list.c b/kernel/bpf/bpf_lru_list.c
index 89b7ef41c86b..b9255a427c28 100644
--- a/kernel/bpf/bpf_lru_list.c
+++ b/kernel/bpf/bpf_lru_list.c
@@ -229,6 +229,7 @@ __bpf_lru_list_shrink_inactive(struct bpf_lru *lru,
                }

                if (++i == lru->nr_scans)
+               if (++i == lru->nr_scans || node == first_node)
                        break;
        }