Re: [lwip-users] lwIP hangs after some data transferred

[Grzegorz Niemirowski]

Grzegorz Niemirowski <address@hidden> napisał(a):
> I'm still fighting with the problem. The stack hangs on fetching packets 
> from mbox. I have tried following code (added printfs):
> printf("fetch %u\n", num++);
> sys_timeouts_mbox_fetch(&mbox, (void **)&msg);
> printf("OK\n");
> And I get "fetch 2272" without "OK".

Further analysis gave following observations:
- thread blocks on fetch because packets are no longer inserted into mbox
- packets are not inserted because the ETH interrupt is no longer raised
- there is no interrupt because reception is suspended, set bits in the 
DMASR register show:
RPS bits: 100: Suspended: Receive descriptor unavailable
RBUS bit: Receive buffer unavailable status
Descriptors are freed inside low_level_input after PBUF has been allocated 
and incoming packet has been copied. But it happens that pbuf_alloc returns 
NULL. What could be the reason? The traffic is not big, just a few kB/s. 
Maybe there is not enough space for PBUFs, but the problem doesn't occur 
immediately, usually a few thousand packets are transmitted without  any 
issue before the stack stalls.

Best regards,
Grzegorz Niemirowski