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With an empty skb this is 0, so the > dump ends with NLMSG_DONE and status 0, and the remaining entries are > lost. > > The first dump skb is allocated from __netlink_dump_start() while > max_recvmsg_len is still 0, so it is only NLMSG_GOODSIZE. On a 4K page > kernel that is under 4000 bytes, and a 500 way multipath route does not > fit: > > ip link add dummy0 type dummy > ip link set dummy0 up > ip route add 198.51.100.0/24 table 100 \ > $(for i in $(seq 500); do echo -n "nexthop dev dummy0 "; done) > ip route show table 100 > > The dump prints nothing and exits 0 > > Only ignore -EMSGSIZE when the skb has data, so that an entry which > does not fit in an empty skb reports the error to user space. > > Fixes: 5b4b62a169e1 ("rtnetlink: make the "split" NLM_DONE handling generic") > Signed-off-by: Stephen Hemminger Reviewed-by: Ido Schimmel