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-rw-r--r--kernel/rcu/tree_plugin.h54
1 files changed, 51 insertions, 3 deletions
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index b70cc91a7831..fe46e7008667 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -1928,6 +1928,33 @@ static void do_nocb_bypass_wakeup_timer(struct timer_list *t)
__call_rcu_nocb_wake(rdp, true, flags);
}
+static inline bool nocb_gp_enabled_cb(struct rcu_data *rdp)
+{
+ u8 flags = SEGCBLIST_OFFLOADED | SEGCBLIST_KTHREAD_GP;
+
+ return rcu_segcblist_test_flags(&rdp->cblist, flags);
+}
+
+static inline bool nocb_gp_update_state(struct rcu_data *rdp, bool *needwake_state)
+{
+ struct rcu_segcblist *cblist = &rdp->cblist;
+
+ if (rcu_segcblist_test_flags(cblist, SEGCBLIST_OFFLOADED)) {
+ return true;
+ } else {
+ /*
+ * De-offloading. Clear our flag and notify the de-offload worker.
+ * We will ignore this rdp until it ever gets re-offloaded.
+ */
+ WARN_ON_ONCE(!rcu_segcblist_test_flags(cblist, SEGCBLIST_KTHREAD_GP));
+ rcu_segcblist_clear_flags(cblist, SEGCBLIST_KTHREAD_GP);
+ if (!rcu_segcblist_test_flags(cblist, SEGCBLIST_KTHREAD_CB))
+ *needwake_state = true;
+ return false;
+ }
+}
+
+
/*
* No-CBs GP kthreads come here to wait for additional callbacks to show up
* or for grace periods to end.
@@ -1956,8 +1983,17 @@ static void nocb_gp_wait(struct rcu_data *my_rdp)
*/
WARN_ON_ONCE(my_rdp->nocb_gp_rdp != my_rdp);
for (rdp = my_rdp; rdp; rdp = rdp->nocb_next_cb_rdp) {
+ bool needwake_state = false;
+ if (!nocb_gp_enabled_cb(rdp))
+ continue;
trace_rcu_nocb_wake(rcu_state.name, rdp->cpu, TPS("Check"));
rcu_nocb_lock_irqsave(rdp, flags);
+ if (!nocb_gp_update_state(rdp, &needwake_state)) {
+ rcu_nocb_unlock_irqrestore(rdp, flags);
+ if (needwake_state)
+ swake_up_one(&rdp->nocb_state_wq);
+ continue;
+ }
bypass_ncbs = rcu_cblist_n_cbs(&rdp->nocb_bypass);
if (bypass_ncbs &&
(time_after(j, READ_ONCE(rdp->nocb_bypass_first) + 1) ||
@@ -2221,7 +2257,8 @@ static void do_nocb_deferred_wakeup(struct rcu_data *rdp)
static int __rcu_nocb_rdp_deoffload(struct rcu_data *rdp)
{
struct rcu_segcblist *cblist = &rdp->cblist;
- bool wake_cb = false;
+ struct rcu_data *rdp_gp = rdp->nocb_gp_rdp;
+ bool wake_cb = false, wake_gp = false;
unsigned long flags;
printk("De-offloading %d\n", rdp->cpu);
@@ -2247,9 +2284,19 @@ static int __rcu_nocb_rdp_deoffload(struct rcu_data *rdp)
if (wake_cb)
swake_up_one(&rdp->nocb_cb_wq);
- swait_event_exclusive(rdp->nocb_state_wq,
- !rcu_segcblist_test_flags(cblist, SEGCBLIST_KTHREAD_CB));
+ raw_spin_lock_irqsave(&rdp_gp->nocb_gp_lock, flags);
+ if (rdp_gp->nocb_gp_sleep) {
+ rdp_gp->nocb_gp_sleep = false;
+ wake_gp = true;
+ }
+ raw_spin_unlock_irqrestore(&rdp_gp->nocb_gp_lock, flags);
+ if (wake_gp)
+ wake_up_process(rdp_gp->nocb_gp_kthread);
+
+ swait_event_exclusive(rdp->nocb_state_wq,
+ !rcu_segcblist_test_flags(cblist, SEGCBLIST_KTHREAD_CB |
+ SEGCBLIST_KTHREAD_GP));
return 0;
}
@@ -2332,6 +2379,7 @@ void __init rcu_init_nohz(void)
rcu_segcblist_init(&rdp->cblist);
rcu_segcblist_offload(&rdp->cblist, true);
rcu_segcblist_set_flags(&rdp->cblist, SEGCBLIST_KTHREAD_CB);
+ rcu_segcblist_set_flags(&rdp->cblist, SEGCBLIST_KTHREAD_GP);
}
rcu_organize_nocb_kthreads();
}