How to synchronize cufft functions

Is there a way to synchronize cufftExecC2C function? Definitely since using pointer of cuComplex, I cannot either
use cudaEventSynchronize or cudaStreamSynchronize which gives be type conversion errors. I have tried to use
cudaThreadSynchronize to solve the problem but it seems it does not help much. Can some one advice me how to
fix this problem? I have black dots appearing on my image which seems to be the problem with synchrnoizing.