[VPP-1543] CLI 'show map stats' before adding a MAP causes segfault

[vvalderrv]

monospaced text
(gdb) where
#0 0x00007ffff6c6bcd3 in vlib_combined_counter_n_counters (cm=cm@entry=0x7fffb767694c)
at /usr/src/debug/vpp-19.01/src/vlib/counter.c:124
#1 0x00007fffaf6f2f9c in show_map_stats_command_fn (vm=<optimized out>, input=<optimized out>,
cmd=<optimized out>)
at /home/jdl/workspace/tnsr-pkgs/work/vpp/build-root/rpmbuild/vpp-19.01/src/plugins/map/map.c:1120
#2 0x00007ffff6c69d96 in vlib_cli_dispatch_sub_commands (
vm=vm@entry=0x7ffff6ec7340 <vlib_global_main>,
cm=cm@entry=0x7ffff6ec7528 <vlib_global_main+488>, input=input@entry=0x7fffb4dcff60,
parent_command_index=<optimized out>) at /usr/src/debug/vpp-19.01/src/vlib/cli.c:607
#3 0x00007ffff6c6a3d7 in vlib_cli_dispatch_sub_commands (
vm=vm@entry=0x7ffff6ec7340 <vlib_global_main>,
cm=cm@entry=0x7ffff6ec7528 <vlib_global_main+488>, input=input@entry=0x7fffb4dcff60,
parent_command_index=<optimized out>) at /usr/src/debug/vpp-19.01/src/vlib/cli.c:568

120 u32
121 vlib_combined_counter_n_counters (const vlib_combined_counter_main_t * cm)
122

{ 123 ASSERT (cm->counters); 124 return (vec_len (cm->counters[0])); 125 }

126
127 u32
128 vlib_simple_counter_n_counters (const vlib_simple_counter_main_t * cm)
(gdb) p cm
$12 = (const vlib_combined_counter_main_t *) 0x7fffb767694c
(gdb) p *cm
$13 =

{counters = 0x0, value_at_last_serialize = 0x0, last_incremental_serialize_index = 0, name = 0x7fffaf6f94db "/map/rx", stat_segment_name = 0x0}

1115 map_domain_counter_lock (mm);
1116 vec_foreach (cm, mm->domain_counters)
1117 {
1118 which = cm - mm->domain_counters;
1119
1120 for (i = 0; i < vlib_combined_counter_n_counters (cm); i++)
1121 {
1122 vlib_get_combined_counter (cm, i, &v);
1123 total_pkts[which] += v.packets;
1124 total_bytes[which] += v.bytes;