Comment 141 for bug 1684993

Reviewed: https://review.opencontrail.org/47318
Committed: http://github.com/Juniper/contrail-third-party/commit/43fba6a6f4e3e62705593669dd96fa3803336517
Submitter: Abhay Joshi (<email address hidden>)
Branch: R3.2

commit 43fba6a6f4e3e62705593669dd96fa3803336517
Author: Ananth Suryanarayana <email address hidden>
Date: Wed Sep 19 14:19:17 2018 -0700

Do not insert already sleeping tbb task back into sleeping list

During testing, it was found that tbb sleeping threads singly linked
list was corrupted and had become circular. This seemingly caused
my_slack count to get permanently stuck at -1, as the sleeping list
traversal would potentially never end.

During testing, using a specific assert, it was confirmed that duplicate
insertion did happen.

Fixed it by modifying the sleeing threads singly linked list into a
doubly linked list and then making sure that a thread if already in
the list is never prepended back as the head of the list.

https://github.com/01org/tbb/issues/86

Change-Id: I79bcd7192ea7c7db732b191503d0747e4b0ff229
Closes-Bug: #1684993