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[lwip-users] Re: [lwip] The timers in the TCP
From: |
Adam Dunkels |
Subject: |
[lwip-users] Re: [lwip] The timers in the TCP |
Date: |
Wed, 08 Jan 2003 22:42:45 -0000 |
Hi!
On Saturday 02 February 2002 16:26, you wrote:
> Hi , I have a question regarding the timers in the tcp module - the delay
> ack and the rtx. This is the scenario:
> while handling a certion tcp_pcb in the main thread in tcp_output, the
> tcp_timer_coarse is called and use the unacked and unsent lists of the
> current handled pcb in the main thread. Is this scenario safe - it seems to
> me that both threads can use the unacked and unsent lists of the same pcb?
You are right - the TCP timers should not be invoked while other TCP/IP code
is executed. This can be assured be either encapsulating the TCP/IP code and
TCP timers in semaphores that blocks whenever one or the other is executing,
but the simplest approach is the one described in a recent mail:
main() {
init_everything();
while(1) {
wait_until_timer_fires_or_packet_is_received();
if(packet_is_received) {
ip_input();
}
if(timer_fired) {
do_timer_stuff_such_as_tcp_slowtmr_or_tcp_fasttmr();
}
}
}
/adam
--
Adam Dunkels <address@hidden>
http://www.sics.se/~adam
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