buglwIP - A Lightweight TCP/IP stack - Bugs: bug #22359, Timing problem with etharp_query()

 
 

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bug #22359: Timing problem with etharp_query()

Submitted by:  Bill Florac <bflorac>
Submitted on:  Tue 19 Feb 2008 07:37:00 AM UTC  
 
Category: ARPSeverity: 3 - Normal
Item Group: Faulty BehaviourStatus: Invalid
Privacy: PublicAssigned to: None
Open/Closed: ClosedPlanned Release: None
lwIP version: None

Tue 19 Feb 2008 05:52:03 PM UTC, comment #2:

The one integral part about lwIP is that its core isn't protected against concurrent access. None of the protocols you find in the core dir nor the etharp implementation may be used from multiple threads (unless protected by your own implementation). The sys, pbuf and mem functions are an exception, though.

If you want to use more than one thread, you either have to use one of the available APIs (socket or netconn) or write your own.

In any case, this is not a bug but an implementation error, so I'm closing it as invalid.

Simon Goldschmidt <goldsimon>
Project Administrator
Tue 19 Feb 2008 08:04:56 AM UTC, comment #1:

Ok, I think I need to rescind this. I have be using (cheating) udp_send() directly from my application avoiding the extra netcon layer. However, netconn is going to put everything under one thread and avoid this problem. Right?

Bill

Bill Florac <bflorac>
Tue 19 Feb 2008 07:37:00 AM UTC, original submission:

In etharp.c, function etharp_query(), if the IP address in not in the cache, it sends out a etharp_request() and proceeds to put the request into the queue (assuming ARP_QUEUEING is enable). While copying the data into the queue, it is posible that we get the Asynchronous respose to our arp request. Which will set the state to STABLE and check the queue. It will see the queue is empty and be happy...However once we finish filling the queue, there is no longer anything to flush to flush it. That is until we receive a message that calls update_arp_entry().

Bill Florac <bflorac>

 

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  • -unavailable- added by goldsimon (Posted a comment)
  • -unavailable- added by bflorac (Submitted the item)
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    Follow 2 latest changes.

    Date Changed By Updated Field Previous Value => Replaced By
    Tue 19 Feb 2008 05:52:03 PM UTCgoldsimonOpen/ClosedOpen=>Closed
    Tue 19 Feb 2008 05:52:02 PM UTCgoldsimonStatusNone=>Invalid

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