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Subject[PATCH] rcu: remove the context test in rcu_read_unlock_special()
Because of commit#26861f and #10f39bb1b2, the context test in
rcu_read_unlock_special() are not needed.

commit#26861f and #10f39bb1b2 ensure ->rcu_read_unlock_special is zero
after rcu_read_unlock(), which implies:

if ->rcu_read_unlock_special is non-zero, the out-most RCU C.S. can
be interrupted or can be preempted, such context is safe to
call rcu_read_unlock_special().

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
---
diff --git a/kernel/rcutiny_plugin.h b/kernel/rcutiny_plugin.h
index 22ecea0..22e2ef1 100644
--- a/kernel/rcutiny_plugin.h
+++ b/kernel/rcutiny_plugin.h
@@ -571,12 +571,6 @@ static noinline void rcu_read_unlock_special(struct task_struct *t)
if (special & RCU_READ_UNLOCK_NEED_QS)
rcu_preempt_cpu_qs();

- /* Hardware IRQ handlers cannot block. */
- if (in_irq() || in_serving_softirq()) {
- local_irq_restore(flags);
- return;
- }
-
/* Clean up if blocked during RCU read-side critical section. */
if (special & RCU_READ_UNLOCK_BLOCKED) {
t->rcu_read_unlock_special &= ~RCU_READ_UNLOCK_BLOCKED;
diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h
index c023464..2bd3689 100644
--- a/kernel/rcutree_plugin.h
+++ b/kernel/rcutree_plugin.h
@@ -338,12 +338,6 @@ static noinline void rcu_read_unlock_special(struct task_struct *t)
rcu_preempt_qs(smp_processor_id());
}

- /* Hardware IRQ handlers cannot block. */
- if (in_irq() || in_serving_softirq()) {
- local_irq_restore(flags);
- return;
- }
-
/* Clean up if blocked during RCU read-side critical section. */
if (special & RCU_READ_UNLOCK_BLOCKED) {
t->rcu_read_unlock_special &= ~RCU_READ_UNLOCK_BLOCKED;
diff --git a/kernel/softirq.c b/kernel/softirq.c
index 671f959..7074f97 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -318,12 +318,8 @@ static inline void invoke_softirq(void)
#else
do_softirq();
#endif
- } else {
- __local_bh_disable((unsigned long)__builtin_return_address(0),
- SOFTIRQ_OFFSET);
+ } else
wakeup_softirqd();
- __local_bh_enable(SOFTIRQ_OFFSET);
- }
}

/*

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