Re: [PATCH iproute2] tc: m_tunnel_key: fix geneve opt output

[Davide Caratti]

On Thu, 2020-06-18 at 18:44 +0800, Hangbin Liu wrote:
> Commit f72c3ad00f3b changed the geneve option output from "geneve_opt"
> to "geneve_opts", which may break the program compatibility. Reset
> it back to geneve_opt.
> 
> Fixes: f72c3ad00f3b ("tc: m_tunnel_key: add options support for vxlan")
> Signed-off-by: Hangbin Liu <liuhang...@gmail.com>
> ---
>  tc/m_tunnel_key.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/tc/m_tunnel_key.c b/tc/m_tunnel_key.c
> index bfec9072..0074f744 100644
> --- a/tc/m_tunnel_key.c
> +++ b/tc/m_tunnel_key.c
> @@ -534,7 +534,7 @@ static void tunnel_key_print_geneve_options(struct rtattr 
> *attr)
>       struct rtattr *i = RTA_DATA(attr);
>       int ii, data_len = 0, offset = 0;
>       int rem = RTA_PAYLOAD(attr);
> -     char *name = "geneve_opts";
> +     char *name = "geneve_opt";
>       char strbuf[rem * 2 + 1];
>       char data[rem * 2 + 1];
>       uint8_t data_r[rem];

... by the way, this patch does not look good to me. It fixes program
compatibility for 

# tc action show 

but at the same time, I think it breaks program compatibility for

# tc -j action show

see below: looking at commit f72c3ad00f3b,

 static void tunnel_key_print_tos_ttl(FILE *f, char *name,
@@ -519,8 +586,7 @@ static int print_tunnel_key(struct action_util *au, FILE 
*f, struct rtattr *arg)
                                        tb[TCA_TUNNEL_KEY_ENC_KEY_ID]);
                tunnel_key_print_dst_port(f, "dst_port",
                                          tb[TCA_TUNNEL_KEY_ENC_DST_PORT]);
-               tunnel_key_print_key_opt("geneve_opts",
-                                        tb[TCA_TUNNEL_KEY_ENC_OPTS]);
+               tunnel_key_print_key_opt(tb[TCA_TUNNEL_KEY_ENC_OPTS])

here "name" was "geneve_opts", with the 's', and it was used here:

                open_json_array(PRINT_JSON, name);

so, the proper way to restore script compatibility is to do something
like:

-       print_string(PRINT_FP, name, "\t%s ", name);
+       print_string(PRINT_FP, NULL, "\t%s ", "geneve_opt");

yes, we can "harmonize" like Simon proposed, but then the fix in the
(currently broken) tdc test case should accept both 'geneve_opts' and
'geneve_opt'. Something similar has been done in the past for act_ife 
see net.git commit 91fa038d9446 ("selftests: tc-testing: fix parsing of
ife type").

-- 
davide