linux-kernel - Re: [PATCH 1/3] LoongArch: Add guess unwinder support

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Date:   Fri, 29 Jul 2022 10:56:23 +0800
From:   Youling Tang <tangyouling@...ngson.cn>
To:     Jinyang He <hejinyang@...ngson.cn>,
        Qing Zhang <zhangqing@...ngson.cn>,
        Huacai Chen <chenhuacai@...nel.org>
Cc:     WANG Xuerui <kernel@...0n.name>, loongarch@...ts.linux.dev,
        linux-kernel@...r.kernel.org, Jiaxun Yang <jiaxun.yang@...goat.com>
Subject: Re: [PATCH 1/3] LoongArch: Add guess unwinder support

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