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Date: Thu, 29 Mar 2012 16:21:44 +0800 From: Lai Jiangshan <laijs@...fujitsu.com> To: "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>, Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...e.hu>, LKML <linux-kernel@...r.kernel.org> 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@...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); - } } /* -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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