PM57067: ASYNCHRONOUS RECVMSG RETURNS EMPTY SOCKADDR

Obtain the fix for this APAR.

APAR status

• Closed as unreproducible in next release.

Error description

• Asynchronous recvmsg returns empty sockaddr information in the
  structure pointed to by msghnameptr.
  A timing condition exists where an asynchronous recvmsg is
  unable to complete immediately when it is processed by the
  TCP/IP stack.  The TCP/IP stack creates an event that is used
  to schedule an SRB to complete the call asynchronously.  Network
  activity occurs that makes the socket readable and the TCP/IP
  stack processes the event, scheduling the SRB for async part 2
  processing.  The part 2 SRB completes and is passed back to
  the PFS where the sockaddr structure is initialized and then
  the return information is stored.  The application unit of
  work that issued the recvmsg was interrupted and is now
  resumed.  The PFS initializes the sockaddr structure and
  then detects the call will complete asynchronously and
  returns control to the application.  The initialization of
  the sockaddr structure cleared the results stored by async
  part 2 processing.
  
  ADDITIONAL SYMPTOMS:
  NFS GFSAMAIN UNKNOWN GFSAX TAE BPXPTATT
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: All users of the IBM Communications Server   *
  *                 for z/OS Version 1 Release 13 IP             *
  ****************************************************************
  * PROBLEM DESCRIPTION: Asynchronous recvmsg() or recvfrom()    *
  *                      complete with empty socket address      *
  *                      structure.                              *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  Asynchronous recvmsg() or recvfrom() complete with empty socket
  address structure.
  When an asynchronous recvmsg() or recvfrom() socket call is
  issued there is a timing condition where the supplied socket
  address may not be filled in with the peers information.
  This can occur when a socket address structure is supplied on
  the socket call and the call is unable to complete immediately.
  TCPIP will create an event to allow for asynchronous completion
  of the socket call and return control to the application.  If
  the application thread gets interrupted and is unable to exit
  the PFS layer before the asynchronous completion of the socket
  call, the socket address information filled in during the
  asynchronous completion will be overlaid with an empty socket
  address structure when the synchronous phase of the call
  exits the PFS layer.
  The PFS layer is failing to detect the call will complete
  asynchronously and is copying the empty socket information
  returned by the TCPIP stack.
  +-------------------------------------------------------------+
  + 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

• The PFS layer modules that support recvmsg() and recvfrom()
  socket calls have been amended to not copy the socket address
  information during the synchronous phase when the socket call
  will complete asynchronously.
  
  ****************************************************************
  * FUNCTION AFFECTED: Communications Server TCP/IP (PM57067)    *
  *                    PFS                                       *
  ****************************************************************
  * DESCRIPTION      : COLDCOMM                                  *
  ****************************************************************
  * TIMING           : Post-APPLY                                *
  ****************************************************************
  If you are running multiple TCP/IP stacks in an MVS image all
  of the TCP/IP stacks must be stopped concurrently before being
  restarted.  An IPL is not required.
  

APAR Information

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

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

  UK76837

Modules/Macros

• EZBPFFSF EZBPFFSM EZBPFSRF EZBPFSRM
  

Fix information

• Fixed component name

  TCP/IP V3 MVS

• Fixed component ID

  5655HAL00

Applicable component levels

• R1D0 PSY UK76837

     UP12/04/03 P F204

Fix is available

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