selftests: mptcp: diag: unique 'cestab' subtest names

It is important to have a unique (sub)test name in TAP, because some CI
environments drop tests with duplicated name.

Some 'cestab' subtests from the diag selftest had the same names, e.g.:

....chk 0 cestab

Now the previous value is taken, to have different names, e.g.:

....chk 2->0 cestab after flush

While at it, the 'after flush' info is added, similar to what is done
with the 'in use' subtests. Also inspired by these 'in use' subtests,
'many' is displayed instead of a large number:

many msk socket present [ ok ]
....chk many msk in use [ ok ]
....chk many cestab [ ok ]
....chk many->0 msk in use after flush [ ok ]
....chk many->0 cestab after flush [ ok ]

Fixes: 81ab772819da ("selftests: mptcp: diag: check CURRESTAB counters")
Cc: [e-mail]
Reviewed-by: Geliang Tang <[e-mail]>
Signed-off-by: Matthieu Baerts (NGI0) <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

tools/testing/selftests/net/mptcp/diag.sh

···
 # $1: cestab nr
 chk_msk_cestab()
 {
-	local cestab=$1
+	local expected=$1
+	local msg="....chk ${2:-${expected}} cestab"
+
+	if [ "${expected}" -eq 0 ]; then
+		msg+=" after flush"
+	fi
 
 	__chk_nr "mptcp_lib_get_counter ${ns} MPTcpExtMPCurrEstab" \
-		 "${cestab}" "....chk ${cestab} cestab" ""
+		 "${expected}" "${msg}" ""
 }
 
 wait_connected()
···
 flush_pids
 
 chk_msk_inuse 0 "2->0"
-chk_msk_cestab 0
+chk_msk_cestab 0 "2->0"
 
 echo "a" | \
 	timeout ${timeout_test} \
···
 flush_pids
 
 chk_msk_inuse 0 "1->0"
-chk_msk_cestab 0
+chk_msk_cestab 0 "1->0"
 
 NR_CLIENTS=100
 for I in `seq 1 $NR_CLIENTS`; do
···
 
 wait_msk_nr $((NR_CLIENTS*2)) "many msk socket present"
 chk_msk_inuse $((NR_CLIENTS*2)) "many"
-chk_msk_cestab $((NR_CLIENTS*2))
+chk_msk_cestab $((NR_CLIENTS*2)) "many"
 flush_pids
 
 chk_msk_inuse 0 "many->0"
-chk_msk_cestab 0
+chk_msk_cestab 0 "many->0"
 
 mptcp_lib_result_print_all_tap
 exit $ret