Goldschmidt Simon wrote:
I stepped a little bit around now. The semaphore causing the
problem is created inside the accept_function() in api_msg.c line 242:
newconn->sem = sys_sem_new(0);
It is then signaled in sent_tcp() in api_msg.c line 159. But
I can't find the file where this (connection specific)
semaphore is ever waited on. So it gets signaled and signaled
and signaled....
That conn->sem seems only to be waited for when running out of memory.
If you always send so little data that you never run out of memory
(or window size), it never gets waited for. Can any other developer
say something on this? I think this behaviour is strange...
I agree. It is treating it as a binary semaphore.
It turns out sys_arch.txt says "Semaphores can be either counting or binary
- lwIP works with both kinds."
And my own port uses a counting semaphore. But the situation that would
tickle this problem would probably be infrequent in practice, but certainly
would appear to happen sometimes.
I've had a quick look and I can't see any dependencies elsewhere on it
being a counting semaphore. So perhaps the answer is that we must mandate a
binary semaphore after all.
Jifl
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