\[ \boxed { {\frac {{\rm d}^{2}}{{\rm d}{x}^{2}}}y \left ( x \right ) +2\,y \left ( x \right ) {\frac {\rm d}{{\rm d}x}}y \left ( x \right ) +f \left ( x \right ) {\frac {\rm d}{{\rm d}x}}y \left ( x \right ) + \left ( {\frac {\rm d}{{\rm d}x}}f \left ( x \right ) \right ) y \left ( x \right ) =0} \]
Mathematica: cpu = 52.088114 (sec), leaf count = 33 \[ \text {DSolve}\left [y(x) f'(x)+f(x) y'(x)+y''(x)+2 y(x) y'(x)=0,y(x),x\right ] \]
Maple: cpu = 0.156 (sec), leaf count = 48 \[ \left \{ y \left ( x \right ) ={\it ODESolStruc} \left ( {\it \_b} \left ( {\it \_a} \right ) ,[ \left \{ {\frac {\rm d}{{\rm d}{\it \_a}}} {\it \_b} \left ( {\it \_a} \right ) =- \left ( {\it \_b} \left ( {\it \_a } \right ) \right ) ^{2}-f \left ( {\it \_a} \right ) {\it \_b} \left ( { \it \_a} \right ) -{\it \_C1} \right \} , \left \{ {\it \_a}=x,{\it \_b} \left ( {\it \_a} \right ) =y \left ( x \right ) \right \} , \left \{ x={ \it \_a},y \left ( x \right ) ={\it \_b} \left ( {\it \_a} \right ) \right \} ] \right ) \right \} \]