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-rw-r--r--kernel/rcu/tree.c11
1 files changed, 11 insertions, 0 deletions
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 6bb8e72bc815..fb7a1b95af71 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -3894,6 +3894,8 @@ static void rcu_barrier_entrain(struct rcu_data *rdp)
{
unsigned long gseq = READ_ONCE(rcu_state.barrier_sequence);
unsigned long lseq = READ_ONCE(rdp->barrier_seq_snap);
+ bool wake_nocb = false;
+ bool was_alldone = false;
lockdep_assert_held(&rcu_state.barrier_lock);
if (rcu_seq_state(lseq) || !rcu_seq_state(gseq) || rcu_seq_ctr(lseq) != rcu_seq_ctr(gseq))
@@ -3902,7 +3904,14 @@ static void rcu_barrier_entrain(struct rcu_data *rdp)
rdp->barrier_head.func = rcu_barrier_callback;
debug_rcu_head_queue(&rdp->barrier_head);
rcu_nocb_lock(rdp);
+ /*
+ * Flush bypass and wakeup rcuog if we add callbacks to an empty regular
+ * queue. This way we don't wait for bypass timer that can reach seconds
+ * if it's fully lazy.
+ */
+ was_alldone = rcu_rdp_is_offloaded(rdp) && !rcu_segcblist_pend_cbs(&rdp->cblist);
WARN_ON_ONCE(!rcu_nocb_flush_bypass(rdp, NULL, jiffies));
+ wake_nocb = was_alldone && rcu_segcblist_pend_cbs(&rdp->cblist);
if (rcu_segcblist_entrain(&rdp->cblist, &rdp->barrier_head)) {
atomic_inc(&rcu_state.barrier_cpu_count);
} else {
@@ -3910,6 +3919,8 @@ static void rcu_barrier_entrain(struct rcu_data *rdp)
rcu_barrier_trace(TPS("IRQNQ"), -1, rcu_state.barrier_sequence);
}
rcu_nocb_unlock(rdp);
+ if (wake_nocb)
+ wake_nocb_gp(rdp, false);
smp_store_release(&rdp->barrier_seq_snap, gseq);
}