selftests/bpf: Enlarge select() timeout for test_maps

stable inclusion
from stable-v4.19.207
commit 4c48bd3aa1a33cb3e8a0eca8330b8f100f43d895
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I5QR5E
CVE: NA

--------------------------------

commit 2d82d73d

0Day robot observed that it's easily timeout on a heavy load host.
-------------------
 # selftests: bpf: test_maps
 # Fork 1024 tasks to 'test_update_delete'
 # Fork 1024 tasks to 'test_update_delete'
 # Fork 100 tasks to 'test_hashmap'
 # Fork 100 tasks to 'test_hashmap_percpu'
 # Fork 100 tasks to 'test_hashmap_sizes'
 # Fork 100 tasks to 'test_hashmap_walk'
 # Fork 100 tasks to 'test_arraymap'
 # Fork 100 tasks to 'test_arraymap_percpu'
 # Failed sockmap unexpected timeout
 not ok 3 selftests: bpf: test_maps # exit=1
 # selftests: bpf: test_lru_map
 # nr_cpus:8
-------------------
Since this test will be scheduled by 0Day to a random host that could have
only a few cpus(2-8), enlarge the timeout to avoid a false NG report.

In practice, i tried to pin it to only one cpu by 'taskset 0x01 ./test_maps',
and knew 10S is likely enough, but i still perfer to a larger value 30.
Reported-by: Nkernel test robot <lkp@intel.com>
Signed-off-by: NLi Zhijian <lizhijian@cn.fujitsu.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Acked-by: NSong Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20210820015556.23276-2-lizhijian@cn.fujitsu.comSigned-off-by: Ntangbin <tangbin_yewu@cmss.chinamobile.com>

tools/testing/selftests/bpf/test_maps.c

@@ -796,7 +796,7 @@ static void test_sockmap(int tasks, void *data)
 
 		FD_ZERO(&w);
 		FD_SET(sfd[3], &w);
-		to.tv_sec = 1;
+		to.tv_sec = 30;
 		to.tv_usec = 0;
 		s = select(sfd[3] + 1, &w, NULL, NULL, &to);
 		if (s == -1) {