PJ40806: CTL-571 AT CCIOFLIH WITH HEAPCHECK OFF

APAR status

• Closed as program error.

Error description

• See Problem Summary.
  

Local fix

• na
  

Problem summary

• APAR NUMBER:  PJ40806
  PRODUCT:  z/TPF
  FUNCTIONAL AREA:  DEBUG TOOL SUPPORT
  SHIPPED IN PUT:  10
  
  ABSTRACT:
  Upon registering the z/TPF debugger for trace by terminal, a
  CTL-571 (possibly at CCIOFLIH) dump may occur.
  
  PACKAGE CONTENTS:
  Source Segments:
  (C) base/cntl/tpf_app_base.cntl
  (C) base/cntl/tpf_app_base_ux.cntl
  (C) base/rt/cdbtbt.c
  (C) base/rt/cdbuxt.c
  
  Object Only Binaries:
  None.
  
  Configuration Independent Binaries:
  (C) base/lib/libCDB0.so
  (C) base/load/CDB0.so
  (C) base/obj/cdbtbt.o
  
  Support Files:
  base/lst/CDB0.map
  base/lst/cdbtbt.lst
  
  OTHER BINARIES TO BUILD: YES
  (C) <sys>/load/CDBX.so
  (C) <sys>/obj/cdbuxt.o
  (C) <sys>/load/IPAT.so
  (C) <sys>/obj/ipat.o
  
  COMMENTS:
  After registering the z/TPF debugger for trace by terminal the
  following sequence of events occurred for a customer on a
  multi-istream configuration:
  
  IS-1: ECB A executes cnsf.c (COMX).
  IS-1: ECB A locks the socket lock.
  IS-1: cnsf.c calls CNSG with the socket lock held.
  IS-1: ECB A goes through the chk3 (cchook) debugger
  inter-module call hooks.
  IS-1: ECB A enters cudu (ccvage) to test if the debugger should
  be started for the program being entered (CNSG).
  IS-1: ECB A attempts to lock the debugger registration lock in
  CUDUDPLE.
  
  IS-2: ECB B is created as a result of some comms request.
  IS-2: ECB B enters cdbtbt.c (CDB0) to indicate if this ECB is a
  candidate for debugging based on the comms type and available
  debugger registration entries on the system.
  IS-2: ECB B locks the debugger registration lock.
  IS-2: An OSA interrupt occurs.
  IS-2: Interrupt handling attempts to lock the socket lock.
  
  As a result, ECBs A and B are deadlocked resulting in a CTL-571
  dump.
  

Problem conclusion

• SOLUTION:
  This situation will be prevented with the following code
  changes:
  1) The NODEBUG PAT setting is intended to prevent debugging of
  any program that acquires or is executed while the socket or
  file system locks are held. This is necessary to prevent
  application/debugger deadlock situations as the debugger makes
  TCP/IP and file system calls in the normal course of operation.
  CNSG is marked as NODEBUG in base/cntl/tpf_app_base.cntl to
  prevent CNSG from being debugged.
  2) cdbtbt.c has been updated to mask off interrupts while the
  debugger registration lock is held.
  3) A few other programs were changed to use the NODEBUG PAT
  setting since locks were shown to be held when debugger code
  was called.
  
  COREQS: NO
  None.
  
  MIGRATION CONSIDERATIONS: YES
  User exit changes:
  The tpf_terminal_user_exit user exit in cdbuxt.c is affected by
  the change in segment cdbtbt.c (CDB0).  Since cdbtbt.c now
  masks interrupts, user code in the user exit
  tpf_terminal_user_exit should be examined to ensure that no
  requests for file I/O etc are made.
  
  Build and load process changes:
  The following programs are now marked as NODEBUG in the PAT:
  DYDY, CVBV, CNSD, CTLA, CNSG, CYF1, CMR0, CMR1, CMR2, CMR3,
  CMR4, and UMR0
  
  
  
  BUILD COMMANDS AND INSTRUCTIONS: YES
  #maketpf commands for linux
  maketpf -f CDBX cdbuxt.o
  maketpf -f CDB0 cdbtbt.o
  maketpf -f IPAT
  maketpf CDBX link TPF_VERIFY_LINK_REFS=NO
  maketpf CDB0 link TPF_VERIFY_LINK_REFS=NO
  maketpf CDBX link
  maketpf CDB0 link
  
  UPDATED INFORMATION UNITS: NO
  None.
  
  See your IBM representative if you need additional information.
  
  DOWNLOAD INSTRUCTIONS:
  http://www.ibm.com/software/htp/tpf/maint/maintztpf.html
  
  APAR URL:
  http://www.ibm.com/software/htp/tpf/ztpfmaint/put10/PJ40806.htm
  

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:

Fix information

• Fixed component name

  Z/TPF

• Fixed component ID

  5748T1501

Applicable component levels

• R110 PSY

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