Re: [lwip-users] Sending with thread safety

[Sergio R. Caprile]

If you are running with NO_SYS=1, you don't have an OS and all you have
is a main loop or equivalent. From within than main loop you will always
call lwIP, no calls from interrupts. This is easy, right ? If you have
an asynchronous event, well, you will signal with a flag and take care
of it in the main loop; this is no different than what is normal for rx.
Sort of:

Asynchronous Tx necessity -> set txflag
controller -> there is Rx -> set rxflag
main loop ->
        sys_check_timeouts();
        rxflag -> netif_input -> tcp_input() -> your application (either
tcp_receive() or tcp_sent())
        txflag -> tcp_sndbuf() -> tcp_write() -> netif_output
                        -> no room -> tcp_poll() will take care later

This is so either for server or client frameworks, and you can see it in
the examples, or read it in the wiki:
http://lwip.wikia.com/wiki/Raw/native_API

If you are running with NO_SYS=0, you have an OS that handles threading.
You will always call lwIP functions from within the same thread, or you
will use netconn or socket, and/or you will ask someone else, not me.