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[George Shuklin <1454158@xxxxxxxxxxxxxxxxxx>]

I'm afraid it isn't possible. Expander hang is rare event and after
reboot it come back to normal work. So this is very edge case.

I believe that problem is not fixed in upstream kernel because ses.c
wasn't changed too much.

Btw, I dig in source code for a little and found that ses.c  calls
actually (after many wrapping functions) blk_execute_rq(), and timeout
violation is clearly not a ses bug...

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https://bugs.launchpad.net/bugs/1454158

Title:
   When SCSI bus hangs SES driver indefinitely block any process
  accessing LED status for devices

Status in linux package in Ubuntu:
  Incomplete

Bug description:
  Ubuntu 14.04, 3.13.0-40-generic

  Configuration:

  SCSI (mpt2sas, 16.100.00.00) with few enclosures with SATA disks.

  Situation:
  One of enclosures is hung and do not reply to any requests (including reset). All sg_* command to any device behind hanged enclosure, including enclosure itself, are stuck in the 'D' state.

  Problem:
  Access to sysfs place processes in 'D' state:

  cat /sys/class/enclosure/5\:0\:46\:0/Slot\ 01/locate

  root       588  0.0  0.0   7152   612 pts/6    D+   08:40   0:00 cat
  /sys/class/enclosure/5:0:46:0/Slot 01/locate

  Proposed solution: Add timeout to ses devices independent of HBA
  driver.

  Rationale: Accessing to sysfs do not expect to be 'real IO' with
  chances to hung in 'D' forever.

  Kernel bugzilla bug: https://bugzilla.kernel.org/show_bug.cgi?id=98121

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