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PM57291: TELNET SHUTDOWN HANGS. MAY RESULT IN ABEND4C5 RC = 74C43134 MODULE EZBTZTRM. FINREVERSAL OF PM20618

A fix is available

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APAR status

  • Closed as unreproducible in next release.

Error description

  • TELNET shutdown hangs.  May result in ABEND4C5 RC = 74C43134
    module EZBTZTRM. This is a FINREVERSAL of FIN APAR PM20618.
    .
    ADDITIONAL SYMPTOMS:
    EZBTVXRC(UK70662 11.222)+000668 S0C4/00000004 with reg 4 zero.
    Reg 4 is expected to point to a TVRP.
    

Local fix

  • This problem can be bypassed by specifying NOSNAEXT in the
    TELNET profile
    

Problem summary

  • ****************************************************************
    * USERS AFFECTED: All users of Communications Server for       *
    *                 z/OS Version 1 Release 10,                   *
    *                 z/OS Version 1 Release 11 and                *
    *                 z/OS Version 1 Release 12 IP Telnet          *
    *                 facilities.                                  *
    ****************************************************************
    * PROBLEM DESCRIPTION: Telnet shutdown hangs following         *
    *                      hang of connection using contention     *
    *                      resolution (SNAEXT).                    *
    ****************************************************************
    * RECOMMENDATION:                                              *
    ****************************************************************
    The problem may be summarized as follows:
    
    1. A small number of connections were started with the
       Telnet server.  These connections negotiated contention
       resolution (SNAEXT in Telnet profile).
    2. A BID is sent to one of the clients during processing
       of a 3270 datastream with a corresponding SNA RH with BB.
       The client returns a positive BID response.  A Telnet
       DUCB processes the BID response and eventually issues
       an asynchronous RECEIVE RPL to VTAM:
    
       EZBTTRCV->....->EZBTVSRP->ISTAICIR->ISTAICI2->ISTAICIO
    
    3. The SRB for this thread exits but the DUCB remains, holding
       the CVB lock in shared mode.  The RECEIVE RPL is successfully
       processed by VTAM.
    
    4. Eventually the inactivity timer task suspends attempting
       to obtain the CVB lock in exclusive mode:
    
       EZBTTTMI->EZBTTCLS->EZBTTTVS->EZBITKOB->EZBITDSS
    
    
    5. A 'P' command is issued to terminate the Telnet server.
       This command hangs due to the these two suspended threads.
    
    6. The problem does not occur when contention resolution is
       disabled (NOSNAEXT specified in Telnet profile).
    +-------------------------------------------------------------+
    + Please check our Communications Server for OS/390 homepages +
    + for common networking tips and fixes.  The URL for these    +
    + homepages can be found in Informational APAR II11334.       +
    +-------------------------------------------------------------+
    

Problem conclusion

Temporary fix

Comments

  • The following changes were made in V1R12:
    
    EZBZASY defined the ASYD eyecatcher.
    EZBZCVB deleted a definition for a pointer to the Receive RPL.
    EZBZTMOD defined a pointer for TVRP delete processor.
    EZBZTVRP defined the TVRP eyecatcher and other fields.
    
    EZBTVRCV was updated to use the TXREF macro to manage the usage
    and releasing of TVRP.
    
    EZBTVSRP was updated to use the TXREF macro to manage the usage
    and releasing of TVRP.
    
    EZBTVXRC was updated to use the TXREF macro to manage the usage
    and releasing of TVRP.
    
    EZBTVXSP was updated to get a shared CVB lock while processing
    a SDT.
    
    EZBTVUT2 was updated with a routine to free the TVRP when its
    reference count goes to zero.
    
    EZBTZMST was updated to set a pointer to the new routine in
    EZBTVUT2.
    
    The following parts were changed due to the changes to EZBZTVRP:
    EZBZTVUT, EZBTVBND, EZBTVCLS, EZBTVOPN, EZBTVRQS, EZBTVRTS,
    EZBTVRTX, EZBTVSCU, EZBTVSHC, EZBTVSIG, EZBTVSLU, EZBTVSND,
    EZBTVSNX, EZBTVTRM, EZBTVXLC, EZBTVXOS, EZBTVXRQ, EZBTVXR2,
    EZBTVXSN, EZBTVXSR, EZBTVXS2, EZBTVXTS, and EZB2TVRP.
    
    EZBDGMAT was changed due to the EZBZCVB change.
    
    The following parts were included for maintenance purposes:
    EZBTTCVB, EZBTVCLR, EZBTVSDT, EZBTVSSC,
    
    
    The following changes were made in V1R13:
    
    EZBZTMOD defined some available space.
    
    EZBTVRCV was updated to use the TXREF macro to manage the usage
    and releasing of TVRP.
    
    EZBTVSRP was updated to use the TXREF macro to manage the usage
    and releasing of TVRP.
    
    EZBTVXRC was updated to use the TXREF macro to manage the usage
    and releasing of TVRP.
    
    EZBTVXR2 was updated to delete a field no longer in use.
    
    
    This is a logical route of PM20618, PM38150, D153450, and
    D155164.
    

APAR Information

  • APAR number

    PM57291

  • Reported component name

    TCP/IP V3 MVS

  • Reported component ID

    5655HAL00

  • Reported release

    1C0

  • Status

    CLOSED UR1

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2012-02-02

  • Closed date

    2012-02-28

  • Last modified date

    2012-12-19

  • APAR is sysrouted FROM one or more of the following:

  • APAR is sysrouted TO one or more of the following:

    UK76603 UK76604

Modules/Macros

  • EZBDGMAT EZBTTCVB EZBTVBND EZBTVCLR EZBTVCLS
    EZBTVOPN EZBTVRCV EZBTVRQS EZBTVRTS EZBTVRTX EZBTVSCU EZBTVSDT
    EZBTVSHC EZBTVSIG EZBTVSLU EZBTVSND EZBTVSNX EZBTVSRP EZBTVSSC
    EZBTVTRM EZBTVXLC EZBTVXOS EZBTVXRC EZBTVXRQ EZBTVXR2 EZBTVXSN
    EZBTVXSP EZBTVXSR EZBTVXS2 EZBTVXTS EZBTXUT2 EZBTZMST EZBZASY
    EZBZCVB  EZBZTMOD EZBZTVRP EZBZTVUT EZB2ASY  EZB2CVB  EZB2TVRP
    

Fix information

  • Fixed component name

    TCP/IP V3 MVS

  • Fixed component ID

    5655HAL00

Applicable component levels

  • R1C0 PSY UK76603

       UP12/04/27 P F204

  • R1D0 PSY UK76604

       UP12/04/27 P F204

Fix is available

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Document Information

Modified date:
19 December 2012