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Re: [lwip-users] Writing a proxy server - how "non-reentrant" is lwip ra

From: wurzel
Subject: Re: [lwip-users] Writing a proxy server - how "non-reentrant" is lwip raw API?
Date: Tue, 14 Jun 2011 21:47:11 -0700

Leon Woestenberg wrote:
> On Wed, Jun 15, 2011 at 2:13 AM, wurzel <address@hidden> wrote:
>> My question is, can I call tcp_write from within a tcp_recv
>> callback?  In this code, I've opened a pair of TCP pcbs and
>> each one's state struct has a "mate" field that points to
>> the other side's state struct to I can get its pcb.
> I think that's a very good question indeed, because we give no
> explicit guarantee in our documentation that this is guaranteed to
> work, AFAIK. A function is called reentrant if it can be interrupted
> and called again before previous calls complete execution. Now, as
> there are global variables in the stack, we cannot easily guarantee
> reentrancy, other than through code validation.

Thanks for the clear answer; that helps a lot.  I don't have interrupts,
but I was worried about the case "A subroutine that is directly or 
indirectly recursive should be reentrant"  not knowing which routines 
might be shared between those paths.

I will now go hunt elsewhere for the cause of my sporadic behavior.  :-)


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