Re: [lwip-users] TCP_SND_QUEUELEN vs TCP_SNDQUEUELEN_OVERFLOW

[address@hidden]

Hmm, that bit of code was rather a quick fix for the problem that 
queuelen was an u8_t and was overflowing very fast and the maximum 
increasement for one call of tcp_enqueue is 3. But that could be done 
better, I agree. Especially care must be taken for misconfiguration 
(TCP_SND_QUEUELEN < 3). In fact, this can be take care of completely by 
checking the configuration.I'll take a look at it for 1.3.1. Thanks for 
reporting.

Simon


Art R. schrieb:
> Greetings,
>
> I was reading the current 1.3.0 release code and ran across something I find
> puzzling.
>
> tcp_out.c 
> line 164-6: 
>   queuelen = pcb->snd_queuelen;
>   /* check for configured max queuelen and possible overflow */
>   if ((queuelen >= TCP_SND_QUEUELEN) || (queuelen >
> TCP_SNDQUEUELEN_OVERFLOW)) {
>
> tcp.h
> lines 333-334:
> #define TCP_SNDQUEUELEN_OVERFLOW (0xffff-3)
>   u16_t snd_queuelen; /* Available buffer space for sending (in tcp_segs).
> */
>
> The default value for TCP_SND_QUEUELEN in opt.h is 8, if I read it
> correctly. In our tests, it typically has values in the range of 20 or so.
>
> The setting for TCP_SNDQUEUELEN_OVERFLOW is 65532  (FFFF-3).
> It does not seem sensible to be comparing pcb->snd_queuelen to both
> TCP_SND_QUEUELEN and TCP_SNDQUEUELEN_OVERFLOW.
> Is this intended? A bug? What is the intended purpose for
> TCP_SNDQUEUELEN_OVERFLOW?
>
> HTH...
>
> Art R.
>
>
>
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>