PM26736: EZBITKRA(HIP61B0 09.077)+000278 S4C5/74F62301 WHEN USING FRCA

Obtain the fix for this APAR.

APAR status

• Closed as unreproducible in next release.

Error description

• A listener is using FRCA.  A connection is completed to the FRCA
  listener, then reset without sending in any requests.  EZBTCRDG
  will obtain the listener lock exclusive while processing the
  reset on the connected socket.  The lock is not released,
  causing EZBITKRA to abend during destruction of the unit of
  work.  EZBTCRDG is clearing the TCB pointer when returning to
  EZBTCRD, causing the lock to not be released.
  .
  KEYWORDS:
  4C5 ABEND4C5 http was ABENDS4C5
  .
  VERIFICATION STEPS:
  1) Dump will show exclusive listen on TCB lock
  2) DUCB holding lock will have call back structure
  RSA  7F288668  Prev 1757B2A0  Next 7F288758  Mod EZBIFRC1
  RSA  7F288760  Prev 7F288668  Next 7F2888B0  Mod EZBITKRA
  .
  ADDITIONAL SYMPTOMS:
  If there are multiple batches to be processed, processing the
  next packet will fail with an abend obtaining the TCB lock:
  EZBITKOB(HIP61B0 09.077)+000BF2 S4C5/74F52002 74F52002
  .
  This is because the listener TCB lock of a FRCA listener is
  already held by the DUCB.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: All users of the IBM Communications Server   *
  *                 for z/OS Version 1 Release(s) 10, 11, and 12 *
  *                 IP:  FRCA                                    *
  ****************************************************************
  * PROBLEM DESCRIPTION: Abend S4C5 RSN74F62301 in EZBITKRA when *
  *                      a client connection is reset while in   *
  *                      the backlog of a FRCA enabled listener. *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  Abend S4C5 RSN74F62301 in EZBITKRA when a client connection is
  reset while in the backlog of a FRCA enabled listener.
  The listener lock is obtained while processing the RST packet
  on the child connection.  The code path in EZBTCRDG fails to
  release the listener lock before exiting.  When the thread
  processing the RST exits the residual lock is detected, forcing
  the abend S4C5.  The listener lock is released during recovery
  processing with no residual side effects.
  +-------------------------------------------------------------+
  + 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

• EZBTCRDG has been amended to release the listener lock while
  processing a RST for a connection in the backlog.
  

APAR Information

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

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

  UK63089 UK63090 UK63091

Modules/Macros

• EZBTCRDG
  

Fix information

• Fixed component name

  TCP/IP V3 MVS

• Fixed component ID

  5655HAL00

Applicable component levels

• R1A0 PSY UK63089

     UP11/02/10 P F102 Ž

• R1B0 PSY UK63090

     UP11/02/10 P F102 Ž

• R1C0 PSY UK63091

     UP11/02/10 P F102 Ž

Fix is available

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