linux-kernel - Re: [PATCH] Add exception handling

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Message-ID: <20210918081242.GK4323@worktop.programming.kicks-ass.net>
Date:   Sat, 18 Sep 2021 10:12:42 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     cgel.zte@...il.com
Cc:     jpoimboe@...hat.com, jbaron@...mai.com, rostedt@...dmis.org,
        ardb@...nel.org, tglx@...utronix.de, mingo@...hat.com,
        bp@...en8.de, x86@...nel.org, hpa@...or.com,
        linux-kernel@...r.kernel.org, Yang Guang <yang.guang5@....com.cn>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: [PATCH] Add exception handling

On Sat, Sep 18, 2021 at 07:47:18AM +0000, cgel.zte@...il.com wrote:
> From: Yang Guang <yang.guang5@....com.cn>

That's not the email address this email is from: cgel.zte@...il.com

In fact, I seem to get a lot of email from cgel.zte@...il.com claiming
to be from different authors. This cannot be right.

> If the type is abnormal input from argument, the code will be NULL.

This is incorrect, in that case @code is uninitialized.

> So it should return as default;

That reasoning escapes me.

Also, there's exactly two callsites to __static_call_transform(), both
take their .type argument directly from __sc_insn(). Please explain how
the value can be out of range.

I'm thinking you're:

 1) not understanding the code (or necessarily even C)
 2) working on the suggestino of some broken automation

Please, go pester other people. I'll go block all email from
cgel.zte@...il.com because it's not a single person and the quality of
patches is below par.

> Signed-off-by: Yang Guang <yang.guang5@....com.cn>
> ---
>  arch/x86/kernel/static_call.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/arch/x86/kernel/static_call.c b/arch/x86/kernel/static_call.c
> index f608e6710300..696da3eccf28 100644
> --- a/arch/x86/kernel/static_call.c
> +++ b/arch/x86/kernel/static_call.c
> @@ -45,6 +45,8 @@ static void __ref __static_call_transform(void *insn, enum insn_type type, void
>  		code = text_gen_insn(RET_INSN_OPCODE, insn, func);
>  		size = RET_INSN_SIZE;
>  		break;
> +	default:
> +		return;
>  	}
>  
>  	if (memcmp(insn, code, size) == 0)
> -- 
> 2.25.1
>