Found by clang-check:
tcp/tcp_timer.c:185:15: warning: Value stored to 'result' is never read
result = tcp_callback(dev, conn, TCP_TIMEDOUT);
^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
tcp/tcp_timer.c:264:23: warning: Value stored to 'result' is never read
result = tcp_callback(dev, listener, TCP_TIMEDOUT);
^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
tcp/tcp_timer.c:300:19: warning: Value stored to 'result' is never read
result = tcp_callback(dev, conn, TCP_TIMEDOUT);
^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
3 warnings generated.