[PATCH v7] app/testpmd: monitor state of primary process when using secondary

[Khadem Ullah]

The crashes are on 22.11, 23.03, 24.11, it is on all dpdk stable versions and 25.07 as well. 
Please first close primary testpmd before secondary testpmd application 
and try to close secondary or execute any of the following commands, 

"show device info all
show port stats all 
show port xstats all 
set fwd rxonly 
set fwd txonly 
start
etc"

We are all agree that these crashes exists. First we were tried 
to prevent the crashes at PMD level, but it was not possible to 
add checks in each PMD. Then we tried to add safety checks 
in ethdev layer, and it was not suitable as with primary closing
all reference to device information (pointers) would lead crashes.

Then we agreed on secondary process monitoring for primary process exiting. 
and it is now resolved on application level, i.e. on testpmd. 

Now, this solution is working perfectly. We can add eal_cleanup for 
gracefull exit. 

Best Regards, 
Khadem