linux-kernel - Re: [PATCH] LoongArch: Make compute_return

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Message-ID: <c9123763-a72e-ce2a-83e3-b3e46cec15b3@loongson.cn>
Date:   Thu, 23 Jun 2022 17:35:54 +0800
From:   Tiezhu Yang <yangtiezhu@...ngson.cn>
To:     Huacai Chen <chenhuacai@...nel.org>
Cc:     WANG Xuerui <kernel@...0n.name>,
        Xuefeng Li <lixuefeng@...ngson.cn>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] LoongArch: Make compute_return_era() return void



On 06/23/2022 05:26 PM, Huacai Chen wrote:
> Hi, Tiezhu,
>
> On Sat, Jun 18, 2022 at 4:39 PM Tiezhu Yang <yangtiezhu@...ngson.cn> wrote:
>>
>> compute_return_era() always returns 0, make it return void,
>> and then no need to check its return value for its callers.
>>
>> Signed-off-by: Tiezhu Yang <yangtiezhu@...ngson.cn>
>> ---
>>  arch/loongarch/include/asm/branch.h | 3 +--
>>  arch/loongarch/kernel/traps.c       | 3 +--
>>  2 files changed, 2 insertions(+), 4 deletions(-)
>>
>> diff --git a/arch/loongarch/include/asm/branch.h b/arch/loongarch/include/asm/branch.h
>> index 3f33c89..9a133e4 100644
>> --- a/arch/loongarch/include/asm/branch.h
>> +++ b/arch/loongarch/include/asm/branch.h
>> @@ -12,10 +12,9 @@ static inline unsigned long exception_era(struct pt_regs *regs)
>>         return regs->csr_era;
>>  }
>>
>> -static inline int compute_return_era(struct pt_regs *regs)
>> +static inline void compute_return_era(struct pt_regs *regs)
>>  {
>>         regs->csr_era += 4;
>> -       return 0;
>>  }
>>
>>  #endif /* _ASM_BRANCH_H */
>> diff --git a/arch/loongarch/kernel/traps.c b/arch/loongarch/kernel/traps.c
>> index e4060f8..1bf58c6 100644
>> --- a/arch/loongarch/kernel/traps.c
>> +++ b/arch/loongarch/kernel/traps.c
>> @@ -475,8 +475,7 @@ asmlinkage void noinstr do_ri(struct pt_regs *regs)
>>
>>         die_if_kernel("Reserved instruction in kernel code", regs);
>>
>> -       if (unlikely(compute_return_era(regs) < 0))
>> -               goto out;
>> +       compute_return_era(regs);
> Maybe it is better to simply remove the compute_return_era() function?

Good idea, if so, I think we can also remove exception_era(), and then
arch/loongarch/include/asm/branch.h can be removed.

If you are OK, I will send a v2 patch to remove
arch/loongarch/include/asm/branch.h

Thanks,
Tiezhu

>
> Huacai
>>
>>         if (unlikely(get_user(opcode, era) < 0)) {
>>                 status = SIGSEGV;
>> --
>> 2.1.0
>>