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Subject: Re: [PATCH 1/3] LoongArch: Add guess unwinder support
To:     Jinyang He <hejinyang@loongson.cn>,
        Qing Zhang <zhangqing@loongson.cn>,
        Huacai Chen <chenhuacai@kernel.org>
References: <20220728140519.5420-1-zhangqing@loongson.cn>
 <1288a80b-4038-126f-aec0-74f18cf2fea2@loongson.cn>
 <b49c5d32-81fb-0c56-16cc-8fe6cafa3957@loongson.cn>
Cc:     WANG Xuerui <kernel@xen0n.name>, loongarch@lists.linux.dev,
        linux-kernel@vger.kernel.org, Jiaxun Yang <jiaxun.yang@flygoat.com>
From:   Youling Tang <tangyouling@loongson.cn>
Message-ID: <67911739-b8f3-578f-4d10-7aabb193ddf1@loongson.cn>
Date:   Fri, 29 Jul 2022 10:56:23 +0800
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Hi, Jinyang

On 07/29/2022 10:28 AM, Jinyang He wrote:
> Hi, Youling,
>
> [...]
>>> +unsigned long unwind_get_return_address(struct unwind_state *state)
>>> +{
>>> +    if (unwind_done(state))
>>> +        return 0;
>> This judgment can be removed, because unwind_done() has been judged
>> before entering this function, and unwind_get_return_address will not
>> be called if it is true.
> These unwinder functions are exported by "EXPORT_SYMBOL_GPL".
> What's more, new ways to use them will be added in the future possible.
> Assuming has judged unwind_done is not reliable.
In this case, most of the code will be checked twice by unwind_done(),
which feels a bit redundant.

Thanks,
Youling