rcu: Fix rcu_read_unlock_strict() strict QS reporting

Kernels built with CONFIG_PREEMPT=n and CONFIG_RCU_STRICT_GRACE_PERIOD=y
report the quiescent state directly from the outermost rcu_read_unlock().
However, the current CPU's rcu_data structure's ->cpu_no_qs.b.norm
might still be set, in which case rcu_report_qs_rdp() will exit early,
thus failing to report quiescent state.

This commit therefore causes rcu_read_unlock_strict() to clear
CPU's rcu_data structure's ->cpu_no_qs.b.norm field before invoking
rcu_report_qs_rdp().

Signed-off-by: Zqiang <qiang1.zhang@intel.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index 438ecae..86772c9 100644 (file)
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -824,6 +824,7 @@ void rcu_read_unlock_strict(void)
        if (irqs_disabled() || preempt_count() || !rcu_state.gp_kthread)
                return;
        rdp = this_cpu_ptr(&rcu_data);
+       rdp->cpu_no_qs.b.norm = false;
        rcu_report_qs_rdp(rdp);
        udelay(rcu_unlock_delay);
 }