linux-kernel - Re: [PATCH] arm64: replace read_lock to rcu lock in call_break

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Message-ID: <560D5939.7080107@linaro.org>
Date:	Thu, 01 Oct 2015 09:03:05 -0700
From:	"Shi, Yang" <yang.shi@...aro.org>
To:	Catalin Marinas <catalin.marinas@....com>
CC:	rostedt@...dmis.org, will.deacon@....com, dave.long@...aro.org,
	panand@...hat.com, linaro-kernel@...ts.linaro.org,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	linux-rt-users@...r.kernel.org
Subject: Re: [PATCH] arm64: replace read_lock to rcu lock in call_break_hook

On 10/1/2015 8:07 AM, Catalin Marinas wrote:
> 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.

Thanks for pointing it out. I'm going to prepare v2 with list_(add|del)_rcu.

Yang

>

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