On Sat, Jul 18, 2020 at 11:55 PM Joel Fernandes (Google) <joel@xxxxxxxxxxxxxxxxx> wrote: [...] > /* If no callbacks moved, nothing more need be done. */ > @@ -419,10 +494,9 @@ void rcu_segcblist_advance(struct rcu_segcblist *rsclp, unsigned long seq) > * callbacks. The overall effect is to copy down the later pointers > * into the gap that was created by the now-ready segments. > */ > - for (j = RCU_WAIT_TAIL; i < RCU_NEXT_TAIL; i++, j++) { > - if (rsclp->tails[j] == rsclp->tails[RCU_NEXT_TAIL]) > - break; /* No more callbacks. */ > + for (j = RCU_WAIT_TAIL; i < RCU_NEXT_TAIL && j < RCU_NEXT_TAIL; i++, j++) { > WRITE_ONCE(rsclp->tails[j], rsclp->tails[i]); > + rcu_segcblist_move_seglen(rsclp, i, j); > rsclp->gp_seq[j] = rsclp->gp_seq[i]; > } Unfortunately I broke this code, _sigh_. I need to reinstate the if (rsclp->tails[j] == rsclp->tails[RCU_NEXT_TAIL]) , I completely misunderstood that.