path: root/net/ipv4/fib_semantics.c
diff options
authorXin Long <lucien.xin@gmail.com>2018-04-01 22:40:35 +0800
committerDavid S. Miller <davem@davemloft.net>2018-04-01 20:57:39 -0400
commit6174a30df1b902e1fedbd728f5343937e83e64e6 (patch)
treee8df044f9eccb9ad38268b1f5a0561dc6b2c50ab /net/ipv4/fib_semantics.c
parentfix typo in command value in drivers/net/phy/mdio-bitbang. (diff)
route: check sysctl_fib_multipath_use_neigh earlier than hash
Prior to this patch, when one packet is hashed into path [1] (hash <= nh_upper_bound) and it's neigh is dead, it will try path [2]. However, if path [2]'s neigh is alive but it's hash > nh_upper_bound, it will not return this alive path. This packet will never be sent even if path [2] is alive. nexthop via dev eth1 weight 1 <--[1] (dead neigh) nexthop via dev eth2 weight 1 <--[2] With sysctl_fib_multipath_use_neigh set is supposed to find an available path respecting to the l3/l4 hash. But if there is no available route with this hash, it should at least return an alive route even with other hash. This patch is to fix it by processing fib_multipath_use_neigh earlier than the hash check, so that it will at least return an alive route if there is when fib_multipath_use_neigh is enabled. It's also compatible with before when there are alive routes with the l3/l4 hash. Fixes: a6db4494d218 ("net: ipv4: Consider failed nexthops in multipath routes") Reported-by: Jianlin Shi <jishi@redhat.com> Signed-off-by: Xin Long <lucien.xin@gmail.com> Acked-by: David Ahern <dsa@cumulusnetworks.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/fib_semantics.c')
1 files changed, 11 insertions, 9 deletions
diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
index e7c602c600ac..c27122f01b87 100644
--- a/net/ipv4/fib_semantics.c
+++ b/net/ipv4/fib_semantics.c
@@ -1746,18 +1746,20 @@ void fib_select_multipath(struct fib_result *res, int hash)
bool first = false;
for_nexthops(fi) {
+ if (net->ipv4.sysctl_fib_multipath_use_neigh) {
+ if (!fib_good_nh(nh))
+ continue;
+ if (!first) {
+ res->nh_sel = nhsel;
+ first = true;
+ }
+ }
if (hash > atomic_read(&nh->nh_upper_bound))
- if (!net->ipv4.sysctl_fib_multipath_use_neigh ||
- fib_good_nh(nh)) {
- res->nh_sel = nhsel;
- return;
- }
- if (!first) {
- res->nh_sel = nhsel;
- first = true;
- }
+ res->nh_sel = nhsel;
+ return;
} endfor_nexthops(fi);