Hi Vipin, 
Glad you got the reason. 
I have only checked it in testpmd, any other application which provides primary-secondary support could also follow the same model. 
This patch only adds stability and robustness to primary-secondary applications. Primary applications can be closed, quit or shutdown 
by various reasons while secondary end-up with dangling pointers.   
Without the primary application, the secondary could not do any rx or tx.