Re: [PATCH -tip/core/rcu] fixes to include/linux/rcupreempt.h

[Steven Rostedt]

Sorry for the late post, I'm finally looking at all my -rt mail.


On Fri, 1 Aug 2008, Paul E. McKenney wrote:

> Hello!
> 
> Compared tip/core/rcu to my latest patchset, and found the following
> issues:
> 
> o	the memory barrier in rcu_exit_nohz() somehow got out of place
> 	(it is correct in mainline as of 2.6.26-rc7).
> 
> o	There is a duplicate declaration of rcu_dyntick_sched.
> 
> The attached patch fixes these.
> 
> Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
> ---
> 
> diff --git a/include/linux/rcupreempt.h b/include/linux/rcupreempt.h
> index f04b64e..84678bf 100644
> --- a/include/linux/rcupreempt.h
> +++ b/include/linux/rcupreempt.h
> @@ -111,7 +111,6 @@ extern struct rcupreempt_trace *rcupreempt_trace_cpu(int cpu);
>  struct softirq_action;
>  
>  #ifdef CONFIG_NO_HZ
> -DECLARE_PER_CPU(struct rcu_dyntick_sched, rcu_dyntick_sched);

In -rt we deleted the first declaration. Is rcu_dyntick_sched defined on
!CONFIG_NO_HZ?

-- Steve

>  
>  static inline void rcu_enter_nohz(void)
>  {
> @@ -122,8 +121,8 @@ static inline void rcu_enter_nohz(void)
>  
>  static inline void rcu_exit_nohz(void)
>  {
> -	smp_mb(); /* CPUs seeing ++ must see later RCU read-side crit sects */
>  	__get_cpu_var(rcu_dyntick_sched).dynticks++;
> +	smp_mb(); /* CPUs seeing ++ must see later RCU read-side crit sects */
>  	WARN_ON(!(__get_cpu_var(rcu_dyntick_sched).dynticks & 0x1));
>  }
>  
> 
--
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