selftests: net: Unify code of busywait() and slowwait()

Bodies of busywait() and slowwait() functions are almost identical. Extract
the common code into a helper, loopy_wait, and convert busywait() and
slowwait() into trivial wrappers.

Moreover, the fact that slowwait() uses seconds for units is really not
intuitive, and the comment does not help much. Instead make the unit part
of the name of the argument to further clarify what units are expected.

Cc: Hangbin Liu <liuhangbin@gmail.com>
Signed-off-by: Petr Machata <petrm@nvidia.com>
Reviewed-by: Benjamin Poirier <bpoirier@nvidia.com>
Reviewed-by: Hangbin Liu <liuhangbin@gmail.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

tools/testing/selftests/net/forwarding/lib.sh

@@ -95,27 +95,9 @@ source "$net_forwarding_dir/../lib.sh"
 # timeout in seconds
 slowwait()
 {
-	local timeout=$1; shift
-
-	local start_time="$(date -u +%s)"
-	while true
-	do
-		local out
-		out=$("$@")
-		local ret=$?
-		if ((!ret)); then
-			echo -n "$out"
-			return 0
-		fi
+	local timeout_sec=$1; shift
 
-		local current_time="$(date -u +%s)"
-		if ((current_time - start_time > timeout)); then
-			echo -n "$out"
-			return 1
-		fi
-
-		sleep 0.1
-	done
+	loopy_wait "sleep 0.1" "$((timeout_sec * 1000))" "$@"
 }
 
 ##############################################################################

tools/testing/selftests/net/lib.sh

@@ -58,9 +58,10 @@ ksft_exit_status_merge()
 		$ksft_xfail $ksft_pass $ksft_skip $ksft_fail
 }
 
-busywait()
+loopy_wait()
 {
-	local timeout=$1; shift
+	local sleep_cmd=$1; shift
+	local timeout_ms=$1; shift
 
 	local start_time="$(date -u +%s%3N)"
 	while true
@@ -74,13 +75,22 @@ busywait()
 		fi
 
 		local current_time="$(date -u +%s%3N)"
-		if ((current_time - start_time > timeout)); then
+		if ((current_time - start_time > timeout_ms)); then
 			echo -n "$out"
 			return 1
 		fi
+
+		$sleep_cmd
 	done
 }
 
+busywait()
+{
+	local timeout_ms=$1; shift
+
+	loopy_wait : "$timeout_ms" "$@"
+}
+
 cleanup_ns()
 {
 	local ns=""