Hi Fotis,
On Fri, Feb 17, 2017 at 12:44:35PM +0200, Fotis Panagiotopoulos wrote:
> Hi,
>
> I have a problem with LWIP, where after some time of normal operation, all
> TCP communications die. After lots of headbanging, I found that tcp_tmr()
> stops beeing called.
>
> I examined the functions sys_check_timeouts() and sys_timeout(), and found
> out that there is a problem when sys_now wraps around.
>
> Specifically in the file timeouts.c, lines 214-220 the following snippet
> fails:
>
> now = sys_now();
> if (next_timeout == NULL) {
> diff = 0;
> timeouts_last_time = now;
> } else {
> diff = now - timeouts_last_time;
> }
>
> When sys_now() returns 0 (due to wrap around), the diff variable gets a
> huge number (as it is unsigned), and the tcp timer (and possibly other
> timers), are scheduled for the very very far future, leading in problematic
> TCP communications.
>
> Anyone faced this problem? Is this a bug in LWIP, or maybe in my porting
> files? Any hints?At which value does your sys_now() wrap ? sys_now() must wrap at 2^32-1. Sylvain
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