Will Smith is on the march toward Oscar. How can Academy voters resist Smith, with gray flecks in his hair, in a true story (well, inspired by a true story, meaning it’s been tightened and prettied up) about a homeless single dad and his son. Smith plays Chris Gardner, a San Francisco salesman trying to unload bulky bone scanners (don’t ask) while his depressed wife, Linda (Thandie Newton), works scut jobs. She splits for New York, leaving hubby and their five-year-old son, Christopher (cutie-patooty Jaden Smith, son of Will and Jada Pinkett), to fend for themselves. Rent is due, but Chris thinks he can pursue happyness (the misspelling is on a mural at the kid’s day-care center) by getting a stockbroker’s job at Dean Witter. The catch? It’s a training program that doesn’t pay until he gets hired, if he gets hired. Soon, father and son are scrounging for food and living in homeless shelters and train-station toilets. All this would cause projectile vomiting if both Smiths didn’t swim against the tearjerker tide in the script by Steven Conrad. Director Gabriele Muccino (the Italian, and better, version of The Last Kiss) resists overkill until the final scenes. And Smith wins our hearts without losing his dignity, as Chris suits up for success by day and fights off despair by night. The role needs gravity, smarts, charm, humor and a soul that’s not synthetic. Smith brings it. He’s the real deal.