The current code for multi-thread decompression is not clear, especially in the aspect of using lock. Refine the code to make it clear. Signed-off-by: Liang Li <liang.z.li@intel.com> Message-Id: <1462433579-13691-9-git-send-email-liang.z.li@intel.com> Signed-off-by: Amit Shah <amit.shah@redhat.com>