PK16990: ABEND401 RC18 ON IOCTL CALL WHEN A SUSPEND IS DONE TO WAIT FOR THE ITSTOR_QUE LOCK 05/12/21 PTF PECHANGE

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• Abend401 rsn 18.  Dump title will show the abend is in BPXTCIOC.
  In this case, EZBPFIOC wants to get the ITSTOR_QUE lock, but it
  is held by another task.  So, EZBITDSS is called to suspend the
  DUCB (which is running in task mode).  Since this is in task
  mode, EZBITDSS calls a WAIT macro with the LINKAGE=SYSTEM
  option.  But, EZBPFIOC runs in AR mode and you cannot issue that
  call in AR mode.  So, an abend401 rsn 18 occurs.
  .
  The following modules execute in AR mode and have the potential
  to hit this abend:
  EZBPFFSM EZBPFIOC EZBPFIO2 EZBPFIO3 EZBPFOPT EZBPFRWW EZBPFSET
  EZBPFSRM EZBPFSRX
  .
  KEYWORDS: ioctl BPX1IOC itProc abends401 s401 401 rsn18 rc18 18
     302 rsn48 abends302 sp231k6 sp241k6
  .
  VERIFICATION STEPS:
  DUCB shows:
  1000000E 11E820A0 113E8000 113E8100 00F8E700 0034 OMPROUTE
                                             00401000  Ab Iu Su Rs
  RSA  113E84A8  Prev 14AE95D0  Next 113E8AA8  Mod EZBPFIOC
  RSA  113E8AB0  Prev 113E84A8  Next 113E8C10  Mod EZBITDSS
  Reg14 in the save area for EZBPFIOC will show an itLock has been
  issued for itstor_que in getstoragelock
  .
  ADDITIONAL SYMPTOMS:
  The TCPIP timer task may also hang.  The DUCB holding the
  ITSTOR_QUE lock in the IPCS TCPIPCS LOCK report will
  be the DUCB representing the timer task ( EZBITTUB ).
  The hang occurs because the DUCB has not been updated
  to reflect that it has been given the lock.  The
  DUCB_LOCKSHELDCOUNT will be 0.  IP CBF x str(EZBDUCB) (where
  x = the DUCB address of ITSTOR_QUE lock holder).
  DUCB_LOCKS_SUSPENDED will be 0 and DUCB_SUSPENDED_NEXT
  will be 7FFAFAF1.  This indicates that another DUCB
  is in the process of resuming the timer task.  This
  is also reflected in the DUCB in that the inuse /
  suspended / resumed flags are on.
  If a task mode PFS request was releasing the
  lock and EZBITTUB was suspended waiting, the post
  issued out of EZBITDRS would abend.
  .
  247F1060 2468F000 2468F100 00F9C480 0035 TCPIP 00000000 Iu Su Rs
  .
  RSA  2468F4A8  Prev 00006D80  Next 2468F6F0  Mod EZBITTUB
  RSA  2468F6F8  Prev 2468F4A8  Next 2468FB80  Mod EZBITSCU
  RSA  2468FB88  Prev 2468F6F8  Next 2468FC38  Mod EZBITKOB
  RSA  2468FC40  Prev 2468FB88  Next 2468FDA0  Mod EZBITDSS
  RSA* 2468FDA8  Prev 2468FC40  Next 00000000  Mod EZBITKSS
  Other symptoms:  ABEND302 RSN 48 indicating POST failed due to
    error in the caller's environment
    Growth in Subpool 231 key 6 and subpool 241 key 6 storage
    because EZBITTUB has been hung and unable to free storage
    from the cache queues.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: All users of the Communications Server for   *
  *                 z/OS Version 1 Release 4, 5, 6, and 7 IP     *
  ****************************************************************
  * PROBLEM DESCRIPTION: Abend 401-18 in IOCTL processing.       *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  Most PFS modules receive control in primary ASC and switch
  to secondary ASC before obtaining the storage lock.  If
  lock contention exists the unit of work is suspended waiting for
  the lock.  An MVS wait is issued for task mode work and results
  in the abend 401-18 due to the secondary ASC.
  
  This problem was introduced by PQ93987.
  +-------------------------------------------------------------+
  + 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

• The PFS layer has been updated to change modes wrapped around
  each WAIT call to prevent the abend.
  
  * Cross Reference between External and Internal Names
  

Temporary fix

Comments

APAR Information

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

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

  UK10492 UK10493 UK10494 UK10495

Modules/Macros

• EZBPFFSM EZBPFIOC EZBPFIO2 EZBPFIO3 EZBPFOPT
  EZBPFRWV EZBPFSRM EZBPFSRX
  

Fix information

• Fixed component name

  TCP/IP V3 MVS

• Fixed component ID

  5655HAL00

Applicable component levels

• R140 PSY UK10492

     UP06/03/01 P F602 «

• R150 PSY UK10493

     UP06/02/16 P F602 «

• R160 PSY UK10494

     UP06/02/16 P F602 «

• R170 PSY UK10495

     UP06/02/16 P F602 «

Fix is available

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