NR_SOFTIRQS
};
-#define SOFTIRQ_STOP_IDLE_MASK (~(1 << RCU_SOFTIRQ))
+/*
+ * Ignoring the RCU vector after ksoftirqd is parked is fine
+ * because:
+ * 1) rcutree_migrate_callbacks() takes care of the queue.
+ * 2) rcu_report_dead() reports the final quiescent states.
+ */
+#define SOFTIRQ_HOTPLUG_SAFE_MASK (BIT(RCU_SOFTIRQ))
/* map softirq index to softirq name. update 'softirq_to_name' in
* kernel/softirq.c when adding a new softirq.
__tick_nohz_full_update_tick(ts, ktime_get());
}
+/*
+ * A pending softirq outside an IRQ (or softirq disabled section) context
+ * should be waiting for ksoftirqd to handle it. Therefore we shouldn't
+ * reach here due to the need_resched() early check in can_stop_idle_tick().
+ *
+ * However if we are between CPUHP_AP_SMPBOOT_THREADS and CPU_TEARDOWN_CPU on the
+ * cpu_down() process, softirqs can still be raised while ksoftirqd is parked,
+ * triggering the below since wakep_softirqd() is ignored.
+ *
+ */
+static bool report_idle_softirq(void)
+{
+ static int ratelimit;
+ unsigned int pending = local_softirq_pending();
+
+ if (likely(!pending))
+ return false;
+
+ /* Some softirqs claim to be safe against hotplug and ksoftirqd parking */
+ if (!cpu_active(smp_processor_id())) {
+ pending &= ~SOFTIRQ_HOTPLUG_SAFE_MASK;
+ if (!pending)
+ return false;
+ }
+
+ if (ratelimit < 10)
+ return false;
+
+ /* On RT, softirqs handling may be waiting on some lock */
+ if (!local_bh_blocked())
+ return false;
+
+ pr_warn("NOHZ tick-stop error: local softirq work is pending, handler #%02x!!!\n",
+ pending);
+ ratelimit++;
+
+ return true;
+}
+
static bool can_stop_idle_tick(int cpu, struct tick_sched *ts)
{
/*
if (need_resched())
return false;
- if (unlikely(local_softirq_pending())) {
- static int ratelimit;
-
- if (ratelimit < 10 && !local_bh_blocked() &&
- (local_softirq_pending() & SOFTIRQ_STOP_IDLE_MASK)) {
- pr_warn("NOHZ tick-stop error: Non-RCU local softirq work is pending, handler #%02x!!!\n",
- (unsigned int) local_softirq_pending());
- ratelimit++;
- }
+ if (unlikely(report_idle_softirq()))
return false;
- }
if (tick_nohz_full_enabled()) {
/*