Commit 089254fd authored by Paul E. McKenney's avatar Paul E. McKenney
Browse files

rcu: Document reason for rcu_all_qs() call to preempt_disable() 



Given that rcu_all_qs() is in non-preemptible kernels, why on earth should
it invoke preempt_disable()?  This commit adds the reason, which is to
work nicely with debugging enabled in CONFIG_PREEMPT_COUNT=y kernels.

Reported-by: default avatarNeeraj Upadhyay <quic_neeraju@quicinc.com>
Reported-by: default avatarBoqun Feng <boqun.feng@gmail.com>
Reported-by: default avatarFrederic Weisbecker <frederic@kernel.org>
Signed-off-by: default avatarPaul E. McKenney <paulmck@kernel.org>
parent 6ca0292c

kernel/rcu/tree_plugin.h

+1 −1
Original line number Diff line number Diff line
@@ -870,7 +870,7 @@ void rcu_all_qs(void) 


	if (!raw_cpu_read(rcu_data.rcu_urgent_qs))

		return;

	preempt_disable();

	preempt_disable();  // For CONFIG_PREEMPT_COUNT=y kernels

	/* Load rcu_urgent_qs before other flags. */

	if (!smp_load_acquire(this_cpu_ptr(&rcu_data.rcu_urgent_qs))) {

		preempt_enable();