-
Alexei Starovoitov authored
CPUs can ask for local route via ip_route_input_noref() concurrently. if nh_rth_input is not cached yet, CPUs will proceed to allocate equivalent DSTs on 'lo' and then will try to cache them in nh_rth_input via rt_cache_route() Most of the time they succeed, but on occasion the following two lines: orig = *p; prev = cmpxchg(p, orig, rt); in rt_cache_route() do race and one of the cpus fails to complete cmpxchg. But ip_route_input_slow() doesn't check the return code of rt_cache_route(), so dst is leaking. dst_destroy() is never called and 'lo' device refcnt doesn't go to zero, which can be seen in the logs as: unregister_netdevice: waiting for lo to become free. Usage count = 1 Adding mdelay() between above two lines makes it easily reproducible. Fix it similar to nh_pcpu_rth_output case. Fixes: d2d68ba9 ("ipv4: Cache input routes in fib_info nexthops.") Signed-off-by:
Alexei Starovoitov <ast@plumgrid.com> Signed-off-by:
David S. Miller <davem@davemloft.net>
dcdfdf56