Lax-Shanghai-Thailand-Singapore-Shanghai-Lax

Hello,

I am flying from Los Angeles to Shanghai and spending less then 72 hours with my cousin. Then I am taking a direct flight to Thailand. After a few days in Thailand, going to Singapore. Then flying from Singapore going back to Shanghai for 48 hours. Then a direct flight to Lax. Basically entering Shanghai twice (once from Los Angeles and once from Singapore), but staying less then 72 hours both times. Do I need a visa?