[PATCH iproute2] vxlan: show correct ttl inherit info

[PATCH iproute2] vxlan: show correct ttl inherit info

[Hangbin Liu]

We should only show ttl inherit when IFLA_VXLAN_TTL_INHERIT supplied.
Otherwise show the ttl number, or auto when it is 0.

Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
---
 ip/iplink_vxlan.c | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/ip/iplink_vxlan.c b/ip/iplink_vxlan.c
index 831f39a..7fc0e2b 100644
--- a/ip/iplink_vxlan.c
+++ b/ip/iplink_vxlan.c
@@ -145,7 +145,7 @@ static int vxlan_parse_opt(struct link_util *lu, int argc, char **argv,
 			NEXT_ARG();
 			check_duparg(&attrs, IFLA_VXLAN_TTL, "ttl", *argv);
 			if (strcmp(*argv, "inherit") == 0) {
-				addattr_l(n, 1024, IFLA_VXLAN_TTL_INHERIT, NULL, 0);
+				addattr(n, 1024, IFLA_VXLAN_TTL_INHERIT);
 			} else if (strcmp(*argv, "auto") == 0) {
 				addattr8(n, 1024, IFLA_VXLAN_TTL, ttl);
 			} else {
@@ -527,12 +527,16 @@ static void vxlan_print_opt(struct link_util *lu, FILE *f, struct rtattr *tb[])
 			print_string(PRINT_FP, NULL, "tos %s ", "inherit");
 	}
 
-	if (tb[IFLA_VXLAN_TTL])
-		ttl = rta_getattr_u8(tb[IFLA_VXLAN_TTL]);
-	if (is_json_context() || ttl)
-		print_uint(PRINT_ANY, "ttl", "ttl %u ", ttl);
-	else
+	if (tb[IFLA_VXLAN_TTL_INHERIT] &&
+	    rta_getattr_u8(tb[IFLA_VXLAN_TTL_INHERIT])) {
 		print_string(PRINT_FP, NULL, "ttl %s ", "inherit");
+	} else if (tb[IFLA_VXLAN_TTL]) {
+		ttl = rta_getattr_u8(tb[IFLA_VXLAN_TTL]);
+		if (is_json_context() || ttl)
+			print_uint(PRINT_ANY, "ttl", "ttl %u ", ttl);
+		else
+			print_string(PRINT_FP, NULL, "ttl %s ", "auto");
+	}
 
 	if (tb[IFLA_VXLAN_LABEL]) {
 		__u32 label = rta_getattr_u32(tb[IFLA_VXLAN_LABEL]);
-- 
2.5.5

Re: [PATCH iproute2] vxlan: show correct ttl inherit info

[Phil Sutter]

Hi Hangbin,

On Thu, Sep 27, 2018 at 03:28:36PM +0800, Hangbin Liu wrote:
> We should only show ttl inherit when IFLA_VXLAN_TTL_INHERIT supplied.
> Otherwise show the ttl number, or auto when it is 0.
> 
> Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
> ---
>  ip/iplink_vxlan.c | 16 ++++++++++------
>  1 file changed, 10 insertions(+), 6 deletions(-)
> 
> diff --git a/ip/iplink_vxlan.c b/ip/iplink_vxlan.c
> index 831f39a..7fc0e2b 100644
> --- a/ip/iplink_vxlan.c
> +++ b/ip/iplink_vxlan.c
> @@ -145,7 +145,7 @@ static int vxlan_parse_opt(struct link_util *lu, int argc, char **argv,
>  			NEXT_ARG();
>  			check_duparg(&attrs, IFLA_VXLAN_TTL, "ttl", *argv);
>  			if (strcmp(*argv, "inherit") == 0) {
> -				addattr_l(n, 1024, IFLA_VXLAN_TTL_INHERIT, NULL, 0);
> +				addattr(n, 1024, IFLA_VXLAN_TTL_INHERIT);

So for VXLAN, the attribute is just added but with a zero value. Looking
at respective kernel code, this seems fine. Now I wonder why for Geneve,
you set the value to 1 and when displaying explicitly check whether the
attribute is there *and* non-zero. OK, looks like Geneve driver always
exports IFLA_GENEVE_TTL_INHERIT. Oddly, I can't find where VXLAN driver
in kernel does export the IFLA_VXLAN_TTL_INHERIT attribute. Am I missing
something?
Do you know why handling of the attributes in both drivers differ?

Cheers, Phil

Re: [PATCH iproute2] vxlan: show correct ttl inherit info

[Hangbin Liu]

On Thu, Sep 27, 2018 at 11:27:45AM +0200, Phil Sutter wrote:
> Hi Hangbin,
> 
> On Thu, Sep 27, 2018 at 03:28:36PM +0800, Hangbin Liu wrote:
> > We should only show ttl inherit when IFLA_VXLAN_TTL_INHERIT supplied.
> > Otherwise show the ttl number, or auto when it is 0.
> > 
> > Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
> > ---
> >  ip/iplink_vxlan.c | 16 ++++++++++------
> >  1 file changed, 10 insertions(+), 6 deletions(-)
> > 
> > diff --git a/ip/iplink_vxlan.c b/ip/iplink_vxlan.c
> > index 831f39a..7fc0e2b 100644
> > --- a/ip/iplink_vxlan.c
> > +++ b/ip/iplink_vxlan.c
> > @@ -145,7 +145,7 @@ static int vxlan_parse_opt(struct link_util *lu, int argc, char **argv,
> >  			NEXT_ARG();
> >  			check_duparg(&attrs, IFLA_VXLAN_TTL, "ttl", *argv);
> >  			if (strcmp(*argv, "inherit") == 0) {
> > -				addattr_l(n, 1024, IFLA_VXLAN_TTL_INHERIT, NULL, 0);
> > +				addattr(n, 1024, IFLA_VXLAN_TTL_INHERIT);
> 
> So for VXLAN, the attribute is just added but with a zero value. Looking
> at respective kernel code, this seems fine. Now I wonder why for Geneve,
> you set the value to 1 and when displaying explicitly check whether the
> attribute is there *and* non-zero. OK, looks like Geneve driver always
> exports IFLA_GENEVE_TTL_INHERIT. Oddly, I can't find where VXLAN driver
> in kernel does export the IFLA_VXLAN_TTL_INHERIT attribute. Am I missing
> something?

Hi Phil,

The vxlan ttl inherit exportation is just fixed by
net commit 8fd78069874 ("vxlan: fill ttl inherit info") yesterday.

> Do you know why handling of the attributes in both drivers differ?

That's because I set IFLA_VXLAN_TTL_INHERIT type to NLA_FLAG. But when fix
the geneve issue, I forgot this and set IFLA_GENEVE_TTL_INHERIT type to
NLA_U8... :(

I noticed this when post the iproute2 patch. But I thought this should have
no much influence, so I just leave it as it is.

If you think we'd better have a same behaver. We can drop the geneve iproute2
patch and post a fix to net kernel tree.

Thanks
Hangbin

Re: [PATCH iproute2] vxlan: show correct ttl inherit info

[Phil Sutter]

Hi Hangbin,

On Thu, Sep 27, 2018 at 10:07:51PM +0800, Hangbin Liu wrote:
> On Thu, Sep 27, 2018 at 11:27:45AM +0200, Phil Sutter wrote:
> > On Thu, Sep 27, 2018 at 03:28:36PM +0800, Hangbin Liu wrote:
> > > We should only show ttl inherit when IFLA_VXLAN_TTL_INHERIT supplied.
> > > Otherwise show the ttl number, or auto when it is 0.
> > > 
> > > Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
> > > ---
> > >  ip/iplink_vxlan.c | 16 ++++++++++------
> > >  1 file changed, 10 insertions(+), 6 deletions(-)
> > > 
> > > diff --git a/ip/iplink_vxlan.c b/ip/iplink_vxlan.c
> > > index 831f39a..7fc0e2b 100644
> > > --- a/ip/iplink_vxlan.c
> > > +++ b/ip/iplink_vxlan.c
> > > @@ -145,7 +145,7 @@ static int vxlan_parse_opt(struct link_util *lu, int argc, char **argv,
> > >  			NEXT_ARG();
> > >  			check_duparg(&attrs, IFLA_VXLAN_TTL, "ttl", *argv);
> > >  			if (strcmp(*argv, "inherit") == 0) {
> > > -				addattr_l(n, 1024, IFLA_VXLAN_TTL_INHERIT, NULL, 0);
> > > +				addattr(n, 1024, IFLA_VXLAN_TTL_INHERIT);
> > 
> > So for VXLAN, the attribute is just added but with a zero value. Looking
> > at respective kernel code, this seems fine. Now I wonder why for Geneve,
> > you set the value to 1 and when displaying explicitly check whether the
> > attribute is there *and* non-zero. OK, looks like Geneve driver always
> > exports IFLA_GENEVE_TTL_INHERIT. Oddly, I can't find where VXLAN driver
> > in kernel does export the IFLA_VXLAN_TTL_INHERIT attribute. Am I missing
> > something?
> 
> Hi Phil,
> 
> The vxlan ttl inherit exportation is just fixed by
> net commit 8fd78069874 ("vxlan: fill ttl inherit info") yesterday.

Ah, thanks!

> > Do you know why handling of the attributes in both drivers differ?
> 
> That's because I set IFLA_VXLAN_TTL_INHERIT type to NLA_FLAG. But when fix
> the geneve issue, I forgot this and set IFLA_GENEVE_TTL_INHERIT type to
> NLA_U8... :(
> 
> I noticed this when post the iproute2 patch. But I thought this should have
> no much influence, so I just leave it as it is.
> 
> If you think we'd better have a same behaver. We can drop the geneve iproute2
> patch and post a fix to net kernel tree.

I guess it doesn't make much difference, but NLA_FLAG would be more
appropriate. If you want to spend the extra effort to fix it, I guess
now's the time - later it can't be changed anymore due to compatibility
issues (I guess).

Thanks, Phil