Outfielder/infielder Brock Holt was placed on the 7-day concussion disabled list (retroactive to May 19) with a mild concussion.
Left fielder/catcher Blake Swihart and right-handed pitcher Noe Ramirez were recalled from Triple-A Pawtucket.
President of Baseball Operations David Dombrowski made the announcement.
Smith, 26, has made three appearances for the Red Sox this season, allowing one unearned run on two hits with one walk and two strikeouts over 2.2 innings. The right-hander, who is in his first season with Boston after being acquired in a trade with the Seattle Mariners on December 7, 2015, began the season on the disabled list with a right flexor muscle strain. He made two rehabilitation assignment appearances with Double-A Portland and was activated from the disabled list on May 3. In 82 career major league games, Smith has gone 3-5 with 13 saves, a 2.00 ERA (18 ER), and 104 strikeouts in only 81.0 innings pitched (11.6 SO/9.0 IP) for the Mariners (2014-15) and Red Sox (2016).
Holt, 27, has hit .239 (27-for-113) with four doubles, three home runs, 19 RBI, and 17 runs scored in 35 games with the Red Sox this season. The left-handed batter has made 29 of his 30 starts in left field, also starting one game at shortstop and making appearances at third base (four games) and second base (three games). Acquired by Boston in a trade with the Pittsburgh Pirates in December 2012, the 2015 American League All-Star has posted a .273 career batting average and .333 on-base percentage in 320 games between the Pirates (2012) and Red Sox (2013-16).
Swihart, 24, made his first career Opening Day roster in 2016, appearing in six games with the Red Sox and batting .278 (5-for-18) with a .391 on-base percentage. He hit .243 (25-for-103) with four doubles and a home run in 29 games with the PawSox after being optioned on April 15, making 14 starts at catcher and 11 in left field. Selected by Boston in the first round of the 2011 June Draft, the switch-hitter has appeared in 90 major league games in two seasons (2015-16), hitting .275 (84-for-306) with 17 doubles, one triple, and five home runs while throwing out 14 of 58 (24.1%) attempted base stealers.
Ramirez, 26, will begin his fourth major league stint with the Red Sox this season. The right-hander was most recently recalled as the club's 26th man for Thursday's doubleheader at Kansas City, but did not appear in either game. After making his first career Opening Day roster with Boston in 2016, Ramirez has appeared in nine games for the club, posting no record with a 5.79 ERA (6 ER/9.1 IP) and 10 strikeouts. For his major league career, Ramirez, a fourth-round selection by the Red Sox in the 2011 June Draft, has gone 0-1 with a 4.84 ERA (12 ER/22.1 IP) and 23 strikeouts in 26 appearances, all with Boston (2015-16).