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rcu: Clear ->rcu_read_unlock_special only once

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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: Lai Jiangshan <laijs@linux.alibaba.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
This commit is contained in:
Lai Jiangshan 2019-11-01 05:06:21 -07:00 committed by Paul E. McKenney
parent 2eeba5838f
commit 3717e1e9f2
1 changed files with 3 additions and 16 deletions
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19
kernel/rcu/tree_plugin.h
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@ -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