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OA50970: TIMER EXIT MAY NOT RUN AFTER TTIMER IS ISSUED WITH OA49676 INSTALLED. CHANGE

A fix is available

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APAR status

  • Closed as program error.

Error description

  • If TTimer is issued without the Cancel option (to test the
    interval timer, which will be referred to as TTimer Test) in the
    window after the clock comparator interrupt (CLKC) occurs for a
    STIMER or STIMERM expiring and before the timer exit is
    dispatched, then the timer exit will not run.
    
    Csect IGC046 (module IEAVRT00) with OA49676 installed sets the
    TQECANCL flag when TTimer Test is issued for a TQE that has
    expired and so has TQEOFF set. This is done for both a level 0
    TQE (STimer Real) and a level 1 TQE (STimerM Set). Now when
    IEAVPLTQ in IEA0TI00 is dispatched to run the Timer exit, the
    Timer exit is not run because TQECANCL is set.
    
    There is another problem: TTimer Cancel will set TQECANCL
    for a level 1 TQE (created via STimerM Set) if the TQE has
    expired and so has TQEOFF set. This will have the same effect
    of preventing the Timer exit from running. This occurs even
    though TTimer should only affect TQEs created by STimer, not
    TQEs created by STimerM.
    
    Problem verification steps:
    Set the following SLIP trap to take a dump when TQECANCL is
    set for TTimer Test/Cancel:
    
    SL SET,IF,ID=TQE1,N=(IGC046,430),DATA=(5R?+7E(7),EQ,0),
        J=jobname,SDATA=(ALLNUC,CSA,PSA,SQA,LPA,TRT,SUM,RGN),
        SUMLIST=(1R?,1R?+79),END
    
    for the jobname whose TQE exit did not run.
    
    If OA50970 is the problem the systrace will show the following
    sequence:
    
    STimerM  Set (or it could be SVC 2E for Stimer Set)
    0000 00C5 00A7D9D0 SVC    2F 00000000_003564F6
                                 47850000 00000000
    CLKC for the TQE expiring
    0000 00C5 00A7D9D0 EXT  CLKC 00000000_00FF05A6
                                 47040000 80000000
    0000 00C5 00A7D9D0 DSP       00000000_00FF05A6
                                 47040000 80000000
    0000 00C5 00A7D9D0 SVCR   2F 00000000_003564F6
                                 47850000 00000000
    
    TTimer Test (or it could be TTimer Cancel)
    0000 00C5 00A7D9D0 SVC    2E 00000000_261952D6
                                 47850000 80000000
    
    IEAVRSAE SRB (IEA0TI00+1544) dispatched on another CPU
    0002 00C5 04D76B80 SRB       00000000_01165EEC
                                 47040000 80000000
    
    SLIP matching at IGC046+430 at TQECANCEL is set
    0000 00C5 00A7D9D0 SPER 4070 00000000_011680CC
                                 44041000 80000000
    
    The TQE@ will be in R1 and the X'01' bit at TQE@+58 will be set.
    
    Note: the SVC 2F or SVC 2E may have wrapped out of the system
    trace. The important thing is that the EXT  CLKC is seen just
    prior to the TTimer Test/Cancel and the IEAVRSAE SRB is
    dispatched after.
    

Local fix

Problem summary

  • ****************************************************************
    * USERS AFFECTED: Users running z/OS HBB7780 and above with    *
    *                 apar OA49676's PTFs applied:                 *
    *                 UA81297 for z/OS V2.2                        *
    *                 UA81298 for z/OS V1.13                       *
    *                 UA81300 for z/OS V2.1                        *
    ****************************************************************
    * PROBLEM DESCRIPTION: 1. MQ batch application may hang and    *
    *                      prevent shutdown of the Queue Manager   *
    *                      after installing PTFs for OA49676.      *
    *                                                              *
    *                      2. A Timer exit may not run after a     *
    *                      TTIMER was issued after installing      *
    *                      PTFs for OA49676.                       *
    ****************************************************************
    * RECOMMENDATION:                                              *
    ****************************************************************
    1. The PTFs for Timer Supervisor APAR OA49676 were PE'd to
    protect customers from the MQ hang reported by MQ APAR PI66686.
    The fix changed how STIMERM EXITs are handled at end of task
    processing, thus requiring a change in MQ processing.  This
    APAR will prereq the PTFs for OA49676 and a req of the fixing
    PTF for MQ apar PI66686.
    
    2. OA49676 caused a change that affected TTIMER processing.
    - If TTIMER without CANCEL (which just tests the
      timer interval) was issued during a window when the STIMER
      is expiring, but before the Timer exit gets dispatched, the
      Timer exit will not run.
    - If TTIMER CANCEL was issued, it may incorrectly cause a
      STIMERM Timer exit not to run.  TTIMER CANCEL should only
      affect STIMER exits.
    

Problem conclusion

  • Fixed TTIMER processing to correctly handle STIMER(M) exits.
    
    In addition, OA50970's PTFs will prereq the PTFs for OA49676
    and a req of the fixing PTF for MQ apar PI66686.
    

Temporary fix

  • *********
    * HIPER *
    *********
    

Comments

  • ×**** PE17/02/06 FIX IN ERROR. SEE APAR OA52075  FOR DESCRIPTION
    

APAR Information

  • APAR number

    OA50970

  • Reported component name

    RTM

  • Reported component ID

    5752SCRTM

  • Reported release

    790

  • Status

    CLOSED PER

  • PE

    YesPE

  • HIPER

    YesHIPER

  • Special Attention

    NoSpecatt / Xsystem

  • Submitted date

    2016-07-29

  • Closed date

    2016-10-20

  • Last modified date

    2017-02-17

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

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

    UA83064 UA83065 UA83075

Modules/Macros

  • IEAVRT00
    

Fix information

  • Fixed component name

    TIMER SUPERVISO

  • Fixed component ID

    5752SC1CV

Applicable component levels

  • R7A0 PSY UA83064

       UP16/11/02 P F611 ­

  • R780 PSY UA83065

       UP16/11/02 P F611 ­

  • R790 PSY UA83075

       UP16/11/02 P F611 ­

Fix is available

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Document Information

Modified date:
17 February 2017