On 18 Dec 2024, at 8:55, Frode Nordahl wrote:
> On Fri, Dec 13, 2024 at 2:56 PM Eelco Chaudron <echau...@redhat.com> wrote:
>>
>>
>>
>> On 10 Dec 2024, at 23:18, Frode Nordahl wrote:
>>
>>> The route-table code is useful outside the scope of Open vSwitch.
>>> In a subsequent patch we will expose the route-table data
>>> structures to allow projects compiling against the private Open
>>> vSwitch library to consume this data.
>>>
>>> The rtnetlink rtmsg rtm_table variable can hold route table IDs no
>>> higher than 256.
>>>
>>> Use the rtnetlink RTA_TABLE route attribute instead, which can
>>> represent a 32 bit integer worth of route tables.
>>>
>>> Signed-off-by: Frode Nordahl <fnord...@ubuntu.com>
>>
>> The code looks good to me. However, what does this mean for backward
>> compatibility? What is the oldest kernel still supported?
>
> That is a good point. In the other direction, we store rtm->rtm_table
> first, and overwrite it if there is a RTA_TABLE attribute.
>
> We could probably do something similar in this direction, as in using
> rtm->rtm_table when value is below threshold and otherwise use
> RTA_TABLE.
>
> That should avoid the issue completely.
I was talking about what if the kernel does not support the RTA_TABLE attribute.
> Thanks!
>
> --
> Frode Nordahl
>
>> Cheers,
>>
>> Eelco
>>
>>> ---
>>> lib/route-table.c | 8 +++++---
>>> 1 file changed, 5 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/lib/route-table.c b/lib/route-table.c
>>> index e7d7a7979..ea56f19c3 100644
>>> --- a/lib/route-table.c
>>> +++ b/lib/route-table.c
>>> @@ -181,7 +181,7 @@ route_table_wait(void)
>>> }
>>>
>>> static bool
>>> -route_table_dump_one_table(unsigned char id)
>>> +route_table_dump_one_table(uint32_t id)
>>> {
>>> uint64_t reply_stub[NL_DUMP_BUFSIZE / 8];
>>> struct ofpbuf request, reply, buf;
>>> @@ -195,7 +195,9 @@ route_table_dump_one_table(unsigned char id)
>>>
>>> rq_msg = ofpbuf_put_zeros(&request, sizeof *rq_msg);
>>> rq_msg->rtm_family = AF_UNSPEC;
>>> - rq_msg->rtm_table = id;
>>> + rq_msg->rtm_table = RT_TABLE_UNSPEC;
>>> +
>>> + nl_msg_put_u32(&request, RTA_TABLE, id);
>>>
>>> nl_dump_start(&dump, NETLINK_ROUTE, &request);
>>> ofpbuf_uninit(&request);
>>> @@ -224,7 +226,7 @@ route_table_dump_one_table(unsigned char id)
>>> static void
>>> route_table_reset(void)
>>> {
>>> - unsigned char tables[] = {
>>> + uint32_t tables[] = {
>>> RT_TABLE_DEFAULT,
>>> RT_TABLE_MAIN,
>>> RT_TABLE_LOCAL,
>>> --
>>> 2.45.2
>>
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