DAC-->KMG-->PVG--> LAX: Am I eligible for visa free transit?

Vivek, because you will transit in two Chinese cities, you aren’t eligible for the 72 hour free transit.
Bur if you transit in PRC for less than 24 hours in total, you are eligible for the 24 direct transit. In this case, you don’t need an entry permit. But if it’s more than 24 hours, you need to apply for an entry permit in advance of your trip.