The Raiders have only 50 players on their 53-player roster after a series of moves Tuesday afternoon.
They signed running back Rod Smith to the active roster.
They also moved tight end Foster Moreau to injured reserve, which was reported earlier in the day.
Smith joins the Raiders after appearing in three contests for the Titans this season.
He entered the league as an undrafted free agent out of Ohio State, signing with the Seahawks in 2015. Smith spent most of his first four seasons with the Cowboys, playing part of the time with his brother, Jaylon Smith.
In his five seasons, Smith has appeared in 52 games and made two starts. He has 101 attempts for 364 yards and five touchdowns, while adding 30 receptions for 272 yards and an additional score.
Brown signed Nov. 18 and played his first game with Oakland on Sunday. He made one tackle in 17 snaps.
McClain played three games with the Raiders after signing Oct. 30.
Swearinger played four games, with three starts, after signing Nov. 9.