Commit 3717e1e9 authored by Lai Jiangshan's avatar Lai Jiangshan Committed by Paul E. McKenney
Browse files

rcu: Clear ->rcu_read_unlock_special only once 



In rcu_preempt_deferred_qs_irqrestore(), ->rcu_read_unlock_special is
cleared one piece at a time.  Given that the "if" statements in this
function use the copy in "special", this commit removes the clearing
of the individual pieces in favor of clearing ->rcu_read_unlock_special
in one go just after it has been determined to be non-zero.

Signed-off-by: default avatarLai Jiangshan <laijs@linux.alibaba.com>
Signed-off-by: default avatarPaul E. McKenney <paulmck@kernel.org>
parent 2eeba583

kernel/rcu/tree_plugin.h

+3 −16
Original line number Diff line number Diff line
@@ -444,16 +444,9 @@ rcu_preempt_deferred_qs_irqrestore(struct task_struct *t, unsigned long flags) 
		local_irq_restore(flags);

		return;

	}

	t->rcu_read_unlock_special.b.exp_hint = false;

	t->rcu_read_unlock_special.b.deferred_qs = false;

	if (special.b.need_qs) {

	t->rcu_read_unlock_special.s = 0;

	if (special.b.need_qs)

		rcu_qs();

		t->rcu_read_unlock_special.b.need_qs = false;

		if (!t->rcu_read_unlock_special.s && !rdp->exp_deferred_qs) {

			local_irq_restore(flags);

			return;

		}

	}



	/*

	 * Respond to a request by an expedited grace period for a
@@ -461,17 +454,11 @@ rcu_preempt_deferred_qs_irqrestore(struct task_struct *t, unsigned long flags) 
	 * tasks are handled when removing the task from the

	 * blocked-tasks list below.

	 */

	if (rdp->exp_deferred_qs) {

	if (rdp->exp_deferred_qs)

		rcu_report_exp_rdp(rdp);

		if (!t->rcu_read_unlock_special.s) {

			local_irq_restore(flags);

			return;

		}

	}



	/* Clean up if blocked during RCU read-side critical section. */

	if (special.b.blocked) {

		t->rcu_read_unlock_special.b.blocked = false;



		/*

		 * Remove this task from the list it blocked on.  The task

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