In CONFIG_PREEMPT=n and CONFIG_PREEMPT_COUNT=y kernel, after a exp
grace period begins, if detected current CPU enters idle in
rcu_exp_handler() IPI handler, will immediately report the exp QS of the
current cpu, at this time, maybe not being in an RCU read-side critical
section, but need wait until rcu-softirq or sched-clock irq or sched-switch
occurs on current CPU to check and report exp QS.
This commit add a exp QS check in rcu_exp_handler(), when not being
in an RCU read-side critical section, report exp QS earlier.
Signed-off-by: Zqiang <qiang1.zhang@xxxxxxxxx>
---
kernel/rcu/tree_exp.h | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/kernel/rcu/tree_exp.h b/kernel/rcu/tree_exp.h
index be667583a554..34f08267410f 100644
--- a/kernel/rcu/tree_exp.h
+++ b/kernel/rcu/tree_exp.h
@@ -828,11 +828,14 @@ static void rcu_exp_handler(void *unused)
{
struct rcu_data *rdp = this_cpu_ptr(&rcu_data);
struct rcu_node *rnp = rdp->mynode;
+ bool preempt_bh_disabled =
+ !!(preempt_count() & (PREEMPT_MASK | SOFTIRQ_MASK));
if (!(READ_ONCE(rnp->expmask) & rdp->grpmask) ||
__this_cpu_read(rcu_data.cpu_no_qs.b.exp))
return;
- if (rcu_is_cpu_rrupt_from_idle()) {
+ if (rcu_is_cpu_rrupt_from_idle() ||
+ (IS_ENABLED(CONFIG_PREEMPT_COUNT) && !preempt_bh_disabled)) {
rcu_report_exp_rdp(this_cpu_ptr(&rcu_data));
return;
}
--
2.25.1
