VM66284: CROSS-SYSTEM LOCK NOT RELEASED IN XDISK STRUCTURE

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• A small window exists in HCPXLKAL that could cause the cross-
  system lock to stay held on a device for a guest that requested
  it.  This could prevent the guest from ever logging off and any
  other process requiring that lock for this XDISK structure to
  hang.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: All z/VM Users                               *
  ****************************************************************
  * PROBLEM DESCRIPTION:                                         *
  ****************************************************************
  * RECOMMENDATION: APPLY PTF                                    *
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  It appears possible that a call to acquire the cross-system lock
  can end up acquiring the lock for a RDEV other than the one the
  XLKAL code was called with.  When HCPXLKAL gets control and that
  RDEV happens to get deleted at the same time, we can end up
  exiting HCPXLKAL with the cross-system lock held on another
  RDEV.  This can only happen if the XLKBK structure has a pointer
  to a XLK-ASS-Lite chain(XLKASSLT field).  Since this field can
  point to another RDEV, we exit with the cross-system lock held
  on that RDEV.  This will result in the cross-system lock never
  being released since the caller of HCPXLKAL checks the RDEV it
  entered XLKAL on to determine if the cross-system lock was held
  or not.
  

Problem conclusion

• HCPXLKAL has been updated to only acquire the cross-system
  lock on the RDEV the code was entered with.
  

Temporary fix

• FOR RELEASE VM/ESA CP/ESA R640 :
  PREREQ: NONE
  CO-REQ: NONE
  IF-REQ: NONE
  FOR RELEASE VM/ESACP/ESAR710 :
  PREREQ: NONE
  CO-REQ: NONE
  IF-REQ: NONE
  

Comments

• ×**** AE20/08/18 FIX IN ERROR. SEE APAR VM66437  FOR DESCRIPTION
  

APAR Information

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

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

  UM35514 UM35515 VM66437

Modules/Macros

• HCPIOJ   HCPLND   HCPLNS   HCPMNO   HCPVDS   HCPXLK
  

Fix information

• Fixed component name

  VM CP

• Fixed component ID

  568411202

Applicable component levels

• R640 PSY UM35514

     UP19/12/18 I 1000 ¢

• R710 PSY UM35515

     UP19/12/18 P 2001 ¢

Fix is available

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