Real and strongly real classes in finite linear groups

We classify the real and strongly real conjugacy classes in $G{L}_n(q)$, $S{L}_n(q)$, $PG{L}_n(q)$, $PS{L}_n(q)$, and all quasi-simple covers of $PS{L}_n(q)$. In each case we give a formula for the number of real, and the number of strongly real, conjugacy classes.