[ECOS] LWIP thread safety

[ECOS] LWIP thread safety

[Rob Duncan]

I've been running into the following assertion failure when I put a
reasonably high load on the LWIP networking stack:

ASSERT FAIL: <6>pbuf.c[577]pbuf_free() pbuf_free: p->ref > 0

According to the LWIP mailing list archives this is typically the
result of incorrect thread protection.  So I've been taking a look at
the way that LWIP is configured in eCos.  I've found that the LWIP
parameter SYS_LIGHTWEIGHT_PROT is not defined, which means that the
pbuf allocate and free routines are not protected (instead there is a
half-hearted attempt at some locking with some state variables but
it's quite broken).  This means that if these routines are called from
multiple threads (which they are), then its only a matter of time
before the pbuf free list or the pbuf reference counts are corrupted.

So, have I misunderstood the implementation?  Have I configured eCos
incorrectly and it ought to be using SYS_LIGHTWEIGHT_PROT?  Has anyone
else run into this problem and solved it?

Any help is appreciated.

Thanks,

Rob.

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