> > Hello, > > My static analysis tool reports a possible ABBA deadlock in the hfi1 driver in > Linux 5.10: > > sc_disable() > write_seqlock(&sc->waitlock); --> Line 956 (Lock A) > hfi1_qp_wakeup() > spin_lock_irqsave(&qp->s_lock, flags); --> Line 441 (Lock B) > > pio_wait() > spin_lock_irqsave(&qp->s_lock, flags); --> Line 939 (Lock B) > write_seqlock(&sc->waitlock); --> Line 941 (Lock A) > > When sc_disable() and pio_wait() are concurrently executed, the deadlock > can occur. > > I am not quite sure whether this possible deadlock is real and how to fix it if it > is real. > Any feedback would be appreciated, thanks :) > > Reported-by: TOTE Robot <oslab@xxxxxxxxxxxxxxx> > > > Best wishes, > Jia-Ju Bai I don't think this can occur, but all other callers to hfi1_qp_wakeup() stash the waiters into an array. I will workup a patch to move the linked list of waiters to a local, drop the lock, and process the local array of waiters. Mike
