Each Tasks RCU flavor keeps a count of the number of callbacks that the current rcu_barrier_tasks*() is waiting on, but there is currently no easy way to work out which callback is stuck. One way to do this is to mark idle RCU-barrier callbacks by making the ->next pointer point to the callback itself, and this commit does just that.
Later commits will use this for debug output. Signed-off-by: Paul E. McKenney <[email protected]> --- kernel/rcu/tasks.h | 2 ++ 1 file changed, 2 insertions(+) diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h index cf273c554f3b0..6f1e82e548bbc 100644 --- a/kernel/rcu/tasks.h +++ b/kernel/rcu/tasks.h @@ -281,6 +281,7 @@ static void cblist_init_generic(struct rcu_tasks *rtp) INIT_LIST_HEAD(&rtpcp->rtp_blkd_tasks); if (!rtpcp->rtp_exit_list.next) INIT_LIST_HEAD(&rtpcp->rtp_exit_list); + rtpcp->barrier_q_head.next = &rtpcp->barrier_q_head; maxcpu = cpu; } @@ -405,6 +406,7 @@ static void rcu_barrier_tasks_generic_cb(struct rcu_head *rhp) struct rcu_tasks *rtp; struct rcu_tasks_percpu *rtpcp; + rhp->next = rhp; // Mark the callback as having been invoked. rtpcp = container_of(rhp, struct rcu_tasks_percpu, barrier_q_head); rtp = rtpcp->rtpp; if (atomic_dec_and_test(&rtp->barrier_q_count)) -- 2.40.1
