PK97575: MULTIPLE S4C5 ABENDS IN EZBTCRD WITH RC 744A2703

Obtain the fix for this APAR.

APAR status

• Closed as unreproducible in next release.

Error description

• Multiple S4C5 abends in EZBTCRD with RC 744A2703 when a timer
  is being cancelled. TID and TQE are not pointing to each other.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: All users of the IBM Communications Server   *
  *                 for z/OS Version 1 Release(s) 9, 10 and      *
  *                 11 IP                                        *
  ****************************************************************
  * PROBLEM DESCRIPTION: Abend S4C5 reason xxxx2703 occurs when  *
  *                      an error condition is detected in the   *
  *                      TCP/IP timer cancel function.  The      *
  *                      timer id (TID) points to a timer        *
  *                      element (TTQE) that does not point      *
  *                      back to the TID.                        *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  Abend S4C5 reason xxxx2703 occurs when an error is detected in
  the TCP/IP timer cancel function.  The TCP/IP timer consists of
  a timer id (TID) and a timer queue element (TTQE).  The abend
  occurs when the TID points to a TTQE that does not point back
  to the TID.
  The error may be a result of a single timer being out of sync
  or a problem with one or more timer chains.  In the event the
  error is related to a timer chain problem the abend may occur
  multiple times as each element on the chain is processed.
  The most likely cause of the problem is a race condition where
  multiple units of work are cancelling the same timer.  The
  cleanup_tcb routine in EZBTCUTL cancels all timers associated
  with a TCP connection that is being terminated.  In certain
  instances cleanup_tcb may be driven by two units of work.
  +-------------------------------------------------------------+
  + 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

• EZBTCUTL has been amended to prevent cleanup_tcb from processing
  more than once for a given TCP connection.
  

APAR Information

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

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

  UK51971 UK51972 UK51973

Modules/Macros

• EZBTCUTL TOTCPDS
  

Fix information

• Fixed component name

  TCP/IP V3 MVS

• Fixed component ID

  5655HAL00

Applicable component levels

• R1A0 PSY UK51971

     UP09/12/17 P F912

• R1B0 PSY UK51972

     UP09/12/17 P F912

• R190 PSY UK51973

     UP09/12/17 P F912

Fix is available

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