* [PATCH] rcu: remove lock acquirement when very eary boot
@ 2010-03-28 3:14 Lai Jiangshan
2010-03-28 4:17 ` Paul E. McKenney
0 siblings, 1 reply; 2+ messages in thread
From: Lai Jiangshan @ 2010-03-28 3:14 UTC (permalink / raw)
To: Paul E. McKenney, Ingo Molnar, LKML
cleanup: remove lock acquirement when very eary boot
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
---
diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index 112edb5..e6014e1 100644
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -1646,13 +1646,10 @@ EXPORT_SYMBOL_GPL(rcu_barrier_sched);
static void __init
rcu_boot_init_percpu_data(int cpu, struct rcu_state *rsp)
{
- unsigned long flags;
int i;
struct rcu_data *rdp = rsp->rda[cpu];
- struct rcu_node *rnp = rcu_get_root(rsp);
/* Set up local state, ensuring consistent view of global state. */
- raw_spin_lock_irqsave(&rnp->lock, flags);
rdp->grpmask = 1UL << (cpu - rdp->mynode->grplo);
rdp->nxtlist = NULL;
for (i = 0; i < RCU_NEXT_SIZE; i++)
@@ -1662,7 +1659,6 @@ rcu_boot_init_percpu_data(int cpu, struct rcu_state *rsp)
rdp->dynticks = &per_cpu(rcu_dynticks, cpu);
#endif /* #ifdef CONFIG_NO_HZ */
rdp->cpu = cpu;
- raw_spin_unlock_irqrestore(&rnp->lock, flags);
}
/*
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] rcu: remove lock acquirement when very eary boot
2010-03-28 3:14 [PATCH] rcu: remove lock acquirement when very eary boot Lai Jiangshan
@ 2010-03-28 4:17 ` Paul E. McKenney
0 siblings, 0 replies; 2+ messages in thread
From: Paul E. McKenney @ 2010-03-28 4:17 UTC (permalink / raw)
To: Lai Jiangshan; +Cc: Ingo Molnar, LKML
On Sun, Mar 28, 2010 at 11:14:13AM +0800, Lai Jiangshan wrote:
>
> cleanup: remove lock acquirement when very eary boot
This is indeed a safe change, however, I am keeping this lock acquisition
and release for documentation purposes. Call me paranoid, but...
Thanx, Paul
> Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
> ---
> diff --git a/kernel/rcutree.c b/kernel/rcutree.c
> index 112edb5..e6014e1 100644
> --- a/kernel/rcutree.c
> +++ b/kernel/rcutree.c
> @@ -1646,13 +1646,10 @@ EXPORT_SYMBOL_GPL(rcu_barrier_sched);
> static void __init
> rcu_boot_init_percpu_data(int cpu, struct rcu_state *rsp)
> {
> - unsigned long flags;
> int i;
> struct rcu_data *rdp = rsp->rda[cpu];
> - struct rcu_node *rnp = rcu_get_root(rsp);
>
> /* Set up local state, ensuring consistent view of global state. */
> - raw_spin_lock_irqsave(&rnp->lock, flags);
> rdp->grpmask = 1UL << (cpu - rdp->mynode->grplo);
> rdp->nxtlist = NULL;
> for (i = 0; i < RCU_NEXT_SIZE; i++)
> @@ -1662,7 +1659,6 @@ rcu_boot_init_percpu_data(int cpu, struct rcu_state *rsp)
> rdp->dynticks = &per_cpu(rcu_dynticks, cpu);
> #endif /* #ifdef CONFIG_NO_HZ */
> rdp->cpu = cpu;
> - raw_spin_unlock_irqrestore(&rnp->lock, flags);
> }
>
> /*
>
^ permalink raw reply [flat|nested] 2+ messages in thread
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2010-03-28 4:17 ` Paul E. McKenney
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