Re: [lwip-devel] [patch #8737] tcp_timer_needed should use tcpip_timeout

[address@hidden]

Robert Szewczyk wrote:
> Follow-up Comment #6, patch #8737 (project lwip):
>
> There are two more things worth bringing up:
> * Even with the warnings in rawapi.txt about thread safety, a programmer might
> lull themselves into a (false) sense of security by thinking: "they warned us
> about the thread safety, but they provided these helpful
> LOCK_TCPIP_CORE/UNLOCK_TCPIP_CORE, so I'll use those in the 'right' places and
> it will be great".  That's the path we pursued.  The particular problem with
> tcpip timers was exposed when we tuned the system to minimize the wakeups.

I hought with calling LOCK_TCPIP_CORE(), tpc_timer_needed() should not 
have to be changed. When not calling it, you're again violating the 
threading requirements.

> * Some functions (as we've discovered recently) are not in the standard API,
> and, yet, they do call into tcp_* methods -- the particular function that came
> to bite us recently was the dhcp_release, which may ultimately close a
> connection.  Perhaps the "proper" solution here would have also been to go
> through tcpip_callback.

That's the reason rawapi.txt includes a whitelist of which header files 
contain funcions hat may be called - the rest is *not* thread-safe.


Simon