selftests: mptcp: userspace_pm: reduce dup code around printf

In this selftest, "printf" is always used with "stdbuf".

With a new helper, it is possible to call "stdbuf" only from one place.
This makes the code a bit clearer to read.
Acked-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

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

@@ -59,21 +59,24 @@ rndh=$(printf %x "$sec")-$(mktemp -u XXXXXX)
 ns1="ns1-$rndh"
 ns2="ns2-$rndh"
 ret=0
+_printf() {
+	stdbuf -o0 -e0 printf "${@}"
+}
 
 print_title()
 {
-	stdbuf -o0 -e0 printf "INFO: %s\n" "${1}"
+	_printf "INFO: %s\n" "${1}"
 }
 
 # $1: test name
 print_test()
 {
-	stdbuf -o0 -e0 printf "%-63s" "${1}"
+	_printf "%-63s" "${1}"
 }
 
 print_results()
 {
-	stdbuf -o0 -e0 printf "[%s]\n" "${1}"
+	_printf "[%s]\n" "${1}"
 }
 
 test_pass()
@@ -93,7 +96,7 @@ test_fail()
 	ret=1
 
 	if [ -n "${1}" ]; then
-		stdbuf -o0 -e0 printf "\t%s\n" "${1}"
+		_printf "\t%s\n" "${1}"
 	fi
 }
 
@@ -127,7 +130,7 @@ cleanup()
 
 	rm -rf $file $client_evts $server_evts
 
-	stdbuf -o0 -e0 printf "Done\n"
+	_printf "Done\n"
 }
 
 trap cleanup EXIT
@@ -288,7 +291,7 @@ check_expected_one()
 		test_fail
 	fi
 
-	stdbuf -o0 -e0 printf "\tExpected value for '%s': '%s', got '%s'.\n" \
+	_printf "\tExpected value for '%s': '%s', got '%s'.\n" \
 		"${var}" "${!exp}" "${!var}"
 	return 1
 }