[lwip-devel] [patch #9601] introduce LWIP_TCP_MAX_TW_BUCKETS to limit timewait socket

[Jin-Seong Kim]

URL:
  <http://savannah.nongnu.org/patch/?9601>

                 Summary: introduce LWIP_TCP_MAX_TW_BUCKETS to limit timewait
socket
                 Project: lwIP - A Lightweight TCP/IP stack
            Submitted by: jseong
            Submitted on: Fri 16 Mar 2018 04:44:12 AM UTC
                Category: TCP
                Priority: 5 - Normal
                  Status: None
                 Privacy: Public
             Assigned to: None
        Originator Email: 
             Open/Closed: Open
         Discussion Lock: Any
         Planned Release: None

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Details:


Dear. All.

We've found some situation that could be possible to make out of memory on
lwIP memory pool.


Test Environment
Test PC (Ubuntu) ---- Wi-Fi  ---- lwIP ported Board (webserver)

Test Procedure
1. Run webserver on board 
 - board has 100kB memory pool for lwIP stack
2. Test PC runs wget more than 1000 times repeatedly
3. wget has been stopped and board doesn't create new TCP seesion
   due to lack of memory

As I checked the memory, the lack of memory is caused by the number of tw
(timewait) pcbs.
In memory constrained board, it can be quite serious issue.
So, I'd like to review my patch which introduce LWIP_TCP_MAX_TW_BUCKETS to
limit timewait socket

Patch description
 - before register tw_tcp_pcbs list, check counter to limit maximum number of
tw pcbs
 - if pcb cannot be in tw_tcp_pcbs, it will freed through tcp_free

Unit-Test Results
Running suite(s): IPv4
 UDP
 TCP
 TCP_OOS
 DEF
 MEM
 NETIF
 PBUF
 TIMERS
 ETHARP
 DHCP
 MDNS
 MQTT
 SOCKETS
100%: Checks: 97, Failures: 0, Errors: 0

Thanks



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File Attachments:


-------------------------------------------------------
Date: Fri 16 Mar 2018 04:44:12 AM UTC  Name:
0001-introduce-LWIP_TCP_MAX_TW_BUCKETS-to-limit-timewait-.patch  Size: 12KiB  
By: jseong
Base commit is 104a629a51
<http://savannah.nongnu.org/patch/download.php?file_id=43566>

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