[En-Nut-Discussion] Race condition and stack overflow in tcpsm.c

[Ole Reinhardt]

Hi Philipp, Hi Harald,

>>> Oops! Yes, you are perfectly right. My solution won't work.
>>
>> Or does it? :-)
> 
> Well, it might, as I wrote earlier. If the thread is not actually
> executing something, this should not be a problem. But it could be a
> problem if some other code tries to access the thread variable before it
> is being assigned a value. But as stated, it is possible that this
> variable isn't used anywhere except in NutTcpInitStateMachine(). As long
> as this is also true in the future, it should work ;)

Well, but what about the following solution? This should fix the problem
with standard Nut/OS functions instead of using application candy and
does not allow other threads to use the thread variables...

HANDLE tcp_initialised = SIGNALED;

int NutTcpInitStateMachine(void)
{
    int rc = 0;
    NutEventWait(&tcp_initialised, NUT_WAIT_INFINITE);
    if (tcpThread == NULL) {
        tcpThread = NutThreadCreate("tcpsm", NutTcpSm, NULL,
NUT_THREAD_TCPSMSTACK * NUT_THREAD_STACK_MULT + NUT_THREAD_STACK_ADD);
        if (tcpThread == NULL) {
            rc = -1;
        }
    }
    NutEventPost(&tcp_initialised);
    return rc;
}

It's the same as with a mutex, but does not use the mutex imlementation.

Bye,

Ole

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