Hello Arnaldo, As part of his attempt to better document the recvmmsg() syscall that you added in commit a2e2725541fad72416326798c2d7fa4dafb7d337, Elie de Brauwer alerted to me to some strangeness in the timeout behavior of the syscall. I suspect there's a bug that needs fixing, as detailed below. AFAICT, the timeout argument was added to this syscall as a result of the discussion here: http://thread.gmane.org/gmane.linux.network/128582 . If I understand correctly, the *intended* purpose of the timeout argument is to set a limit on how long to wait for additional datagrams after the arrival of an initial datagram. However, the syscall behaves in quite a different way. Instead, it potentially blocks forever, regardless of the timeout. The way the timeout seems to work is as follows: 1. The timeout, T, is armed on receipt of first diagram, starting at time X. 2. After each further datagram is received, a check is made if we have reached time X+T. If we have reached that time, then the syscall returns. Since the timeout is only checked after the arrival of each datagram, we can have scenarios like the following: 0. Assume a timeout of 10 seconds, and that vlen is 5. 1. First datagram arrives at time X. 2. Second datagram arrives at time X+2 secs 3. No more datagrams arrive. In this case, the call blocks forever. Is that intended behavior? (Basically, if vlen-1 datagrams arrive before X+T, but then no more datagrams arrive, the call will remain blocked forever.) If it's intended behavior, could you elaborate the use case, since it would be good to add that to the man page. Thanks, Michael -- To unsubscribe from this list: send the line "unsubscribe linux-man" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
