IJ54211: SYSTEM CRASH IN FASTLO_SETUP APPLIES TO AIX 7300-03

APAR status

• Closed as program error.

Error description

• System may crash with following stack trace under rare
  timing window.
  
  [0002CBA0]abend_trap+000000 ()
  [006CB0B0]slock+000610 (??, ??)
  [000090C8].disable_lock+0000C4 (??, ??, ??, ??, ??, ??,
  ??, ??, ??, ??, ??, ??, ??, ??, ??, ??)
  [085C9EEC]netinet:fastlo_setup+00010C (??, ??)
  [085AC47C]netinet:tcp_input0+006DFC (??, ??, ??, ??)
  [085B1A80]netinet:tcp_input+0001A0 (F10010002DB4D600,
  0000000000000001)
  [0858909C]netinet:ipintr_noqueue_post_fw+000B5C
  (0000000000000000, F10010002DB4D600,
     0000000000000000)
  [0858A354]netinet:ipintr_noqueue+0001D4 (??, ??, ??)
  [0858A504]netinet:ipintr+0000E4 ()
  [001502E0]IPRA.$i_offlevel+000120 (??, ??)
  [0014FBE8]i_softmod+0005C8 ()
  [0027B878]flih_util+000258 ()
  

Local fix

• Disable tcp_fastlo to prevent the crash.
  
  # no -po tcp_fastlo=0
  

Problem summary

• System crash in netinet: fastlo_setup.  It crashed due to
  recurring locking.
  
  (13)> where pvthread+22DA00 STACK:   0002CBA0 abend_trap+000000
  ()  006CB0B0 slock+000610 (??, ??)
   000090C8 .disable_lock+0000C4 (??, ??, ??, ??, ??, ??, ??, ??,
  ??, ??, ??, ??, ??, ??, ??, ??)  085C9EEC fastlo_setup+00010C
  (??, ??)  085AC47C tcp_input0+006DFC (??, ??, ??, ??)
   085B1A80 tcp_input+0001A0 (F10010002DB4D600, 0000000000000001)
   0858909C ipintr_noqueue_post_fw+000B5C (0000000000000000,
  F10010002DB4D600, 0000000000000000)
   0858A354 ipintr_noqueue+0001D4 (??, ??, ??)
   0858A504 ipintr+0000E4 ()  001502E0 IPRA.$i_offlevel+000120
  (??, ??)  0014FBE8 i_softmod+0005C8 ()
   0027B878 flih_util+000258 ()
  

Problem conclusion

• Added extra checks before accessing critical section, to avoid
  system dump.
  

Temporary fix

Comments

APAR Information

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

  IJ53476

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

Fix information

• Fixed component name

  AIX V7.3

• Fixed component ID

  5765CD300

Applicable component levels