Erdős Problem #999 — The Duffin–Schaeffer approximation criterion

For nonnegative numbers $ψ(q)$, is divergence of $Σ_{q≥1}φ(q)ψ(q)/q$ necessary and sufficient for $|α-p/q|<ψ(q)/q$ to have infinitely many coprime solutions $(p,q)$ for almost every $α$?