Description of problem:
on controller failure, the I/Os are failover to the available paths and
corresponding sas devices of the failed paths are removed. on re-enabling the
controller, not all the failed paths are failed back. 
Subsequent failure of the other controller, results in all path failure
condition( since it failed to failback the failed paths in previous step)
and read/write error for the luns are observed. 

Version-Release number of selected component (if applicable):
 Array: MSA 2000 with SAS connectivity(MSA2012sa), dual controller 
 Array firmware : J300p10
 mptsas driver version: mptlinux-3.12.14.00-2
 Number of luns presented to host: 15

How reproducible:
Frequently

Steps to Reproduce:
1. Fail one of Array controller, I/Os are failover to available paths.
2. Enable the failed array controller, all failed paths are not restored
3. Fail other array controller.
4. Read/write error to the SAS devices are observed.
  
Actual results:
On Enabling the failed array controller, not all failed paths are failed back. 

Expected results:
On Enabling the failed array controller, all failed paths needs to be enabled.

Additional info:
On heavy load, the DM generated uevents to add/remove the maps/paths are
delayed. Few of the uevents are lost which results in the failure to fail back
the failed paths.


Thanks!