On 6/21/19 9:45 AM, Stefano Brivio wrote:
> Since commit 4895c771c7f0 ("ipv4: Add FIB nexthop exceptions."), cached
> exception routes are stored as a separate entity, so they are not dumped
> on a FIB dump, even if the RTM_F_CLONED flag is passed.
>
> This implies that the command 'ip route list cache' doesn't return any
> result anymore.
>
> If the RTM_F_CLONED is passed, and strict checking requested, retrieve
> nexthop exception routes and dump them. If no strict checking is
> requested, filtering can't be performed consistently: dump everything in
> that case.
>
> With this, we need to add an argument to the netlink callback in order to
> track how many entries were already dumped for the last leaf included in
> a partial netlink dump.
>
> A single additional argument is sufficient, even if we traverse logically
> nested structures (nexthop objects, hash table buckets, bucket chains): it
> doesn't matter if we stop in the middle of any of those, because they are
> always traversed the same way. As an example, s_i values in [], s_fa
> values in ():
>
> node (fa) #1 [1]
> nexthop #1
> bucket #1 -> #0 in chain (1)
> bucket #2 -> #0 in chain (2) -> #1 in chain (3) -> #2 in chain (4)
> bucket #3 -> #0 in chain (5) -> #1 in chain (6)
>
> nexthop #2
> bucket #1 -> #0 in chain (7) -> #1 in chain (8)
> bucket #2 -> #0 in chain (9)
> --
> node (fa) #2 [2]
> nexthop #1
> bucket #1 -> #0 in chain (1) -> #1 in chain (2)
> bucket #2 -> #0 in chain (3)
>
> it doesn't matter if we stop at (3), (4), (7) for "node #1", or at (2)
> for "node #2": walking flattens all that.
>
> It would even be possible to drop the distinction between the in-tree
> (s_i) and in-node (s_fa) counter, but a further improvement might
> advise against this. This is only as accurate as the existing tracking
> mechanism for leaves: if a partial dump is restarted after exceptions
> are removed or expired, we might skip some non-dumped entries.
...
>
> Fixes: 4895c771c7f0 ("ipv4: Add FIB nexthop exceptions.")
> Signed-off-by: Stefano Brivio <sbri...@redhat.com>
> ---
> include/net/route.h | 4 +++
> net/ipv4/fib_trie.c | 44 +++++++++++++++++++--------
> net/ipv4/route.c | 73 +++++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 108 insertions(+), 13 deletions(-)
>
Reviewed-by: David Ahern <dsah...@gmail.com>
