RE: [lwip-users] Dropping existing TCP connections to service new ones

[Bill Auerbach]

> OR will someone someday 'fix' the MAX value, setting it to 255? Is it
> intentional that 'MAX' is 127? Should TCP_PRIO_MAX be renamed to
> TCP_PRIO_HALF_MAX (<smile>)?

But then you'd have to change source code to get what you want working. :-)

I'm guessing that in the olden days that the prio was a signed char, which
would have made 127 the real max.

This reminds me that there are types used in lwIP that should be allowed to
overridden in the sys_arch.h file because a type may be a better fit for the
architecture.  One that comes to mind is err_t which is s_8t.  For some
platforms, s_16t or s_32t are better.

Bill

> Art R. wrote:
> >
> > Setting to max+1 would probably work. I was thinking that the MAX value
> of
> > 127 is the limit of the prio value (an int), but it's an unsigned 8 so
> 128
> > would be ok.
> >
> >
> >
> > Bill Auerbach wrote:
> >>
> >>
> >>> -----Original Message-----
> >>> From: address@hidden
> >>> [mailto:address@hidden On
> >>> Behalf
> >>> Of Art R.
> >>> Sent: Wednesday, February 20, 2008 2:04 PM
> >>> To: address@hidden
> >>> Subject: [lwip-users] Dropping existing TCP connections to service new
> >>> ones
> >>>
> >>>
> >>> The tcp.c module has function tcp_kill_prio which is used to kill
> >>> existing
> >>> TCP connections when a new connection is being attempted and there is
> an
> >>> 'out of PCBs' situation. The comment in that function says "kill the
> >>> oldest
> >>> active connection that has lower priority than prio", but the test it
> >>> performs is "...pcb->prio <= prio". This appears to allow a new
> >>> connection
> >>> to kill an existing one of the same priority.
> >>>
> >>> The default case is that all pcbs will have the same priority
> >>> ("normal"),
> >>> so
> >>> the oldest is killed.
> >>>
> >>> Is this a bug? Should the code read "if (pcb->prio < prio && ..."
> (less
> >>> than instead of less or equal)?
> >>> Or is it intentional?
> >>>
> >>> What would be the best way to disable the killing of active
> connections?
> >>> (Preferably without modifying the lwIP source code.)
> >>
> >> Can't you call tcp_setprio with a value of TCP_PRIO_MAX+1 for each pcb?
> >>
> >> Bill
> >>
> >>
> >>
> >>
> >> _______________________________________________
> >> lwip-users mailing list
> >> address@hidden
> >> http://lists.nongnu.org/mailman/listinfo/lwip-users
> >>
> >>
> >
> >
> 
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> 
> 
> 
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