Re: [PATCH] arm64: replace read_lock to rcu lock in call_break_hook

[Catalin Marinas]

On Wed, Sep 30, 2015 at 03:59:04PM -0700, Yang Shi wrote:
> diff --git a/arch/arm64/kernel/debug-monitors.c b/arch/arm64/kernel/debug-monitors.c
> index cebf786..eb520d0 100644
> --- a/arch/arm64/kernel/debug-monitors.c
> +++ b/arch/arm64/kernel/debug-monitors.c
> @@ -292,11 +292,11 @@ static int call_break_hook(struct pt_regs *regs, unsigned int esr)
>  	struct break_hook *hook;
>  	int (*fn)(struct pt_regs *regs, unsigned int esr) = NULL;
>  
> -	read_lock(&break_hook_lock);
> +	rcu_read_lock();
>  	list_for_each_entry(hook, &break_hook, node)
>  		if ((esr & hook->esr_mask) == hook->esr_val)
>  			fn = hook->fn;
> -	read_unlock(&break_hook_lock);
> +	rcu_read_unlock();
>  
>  	return fn ? fn(regs, esr) : DBG_HOOK_ERROR;
>  }

That's not enough, you also need list_(add|del)_rcu where the list is
modified, together with list_for_each_entry_rcu() here.

-- 
Catalin
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