Sheffield United midfielder Samir Carruthers is wanted by Oxford United.
Karl Robinson left Charlton Athletic by mutual consent on Thursday, with Lee Bowyer being appointed as caretaker manager in his place.
Peterborough manager Grant McCann latest to be considered by Barnsley - what about Bristol Rovers, Charlton and Shrewsbury bosses as well?
Joe Dodoo is yet to start a League One game in Charlton colours after moving on loan from Rangers in the summer.
Charlton defender Ezri Konsa has attracted major interest.
Karl Robinson has shared how he was prevented from signing Harry Winks at MK Dons.
Glasgow Rangers forward Joe Dodoo has left Ibrox for Charlton Athletic on a season-long loan.
Chris Wood has joined Burnley from Leeds United in the summer transfer window.
Charlton could face competition from Wigan Athletic for O'Shea, who helped Sheffield United to the League One title this season.
The right-back moved to Ibrox during last summer's transfer window but has appeared just once under new Rangers boss Pedro Caixinha.