linux-kernel - Re: [PATCH] x86, microcode, AMD: Cocci spatch "memdup.spatch"

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Message-ID: <20130602102137.GA3441@nazgul.tnic>
Date:	Sun, 2 Jun 2013 12:21:37 +0200
From:	Borislav Petkov <bp@...en8.de>
To:	Thomas Meyer <thomas@...3r.de>
Cc:	herrmann.der.user@...glemail.com, tglx@...utronix.de,
	mingo@...hat.com, hpa@...or.com, x86@...nel.org,
	amd64-microcode@...64.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86, microcode, AMD: Cocci spatch "memdup.spatch"

On Sat, Jun 01, 2013 at 11:42:11AM +0200, Thomas Meyer wrote:
> 
> Signed-off-by: Thomas Meyer <thomas@...3r.de>
> ---
> 
> diff -u -p a/arch/x86/kernel/microcode_amd.c b/arch/x86/kernel/microcode_amd.c
> --- a/arch/x86/kernel/microcode_amd.c
> +++ b/arch/x86/kernel/microcode_amd.c
> @@ -345,7 +345,7 @@ static int verify_and_add_patch(unsigned
>  		return -EINVAL;
>  	}
>  
> -	patch->data = kzalloc(patch_size, GFP_KERNEL);
> +	patch->data = kmemdup(fw + SECTION_HDR_SIZE, patch_size, GFP_KERNEL);
>  	if (!patch->data) {
>  		pr_err("Patch data allocation failure.\n");
>  		kfree(patch);
> @@ -353,7 +353,6 @@ static int verify_and_add_patch(unsigned
>  	}
>  
>  	/* All looks ok, copy patch... */
> -	memcpy(patch->data, fw + SECTION_HDR_SIZE, patch_size);
>  	INIT_LIST_HEAD(&patch->plist);
>  	patch->patch_id  = mc_hdr->patch_id;
>  	patch->equiv_cpu = proc_id;

I can see what happens with a little code browsing of the definition of
kmemdup but patches without a commit message are most times not a very
elegant thing.

So please add a nice commit message explaining why you're doing what
you're doing. If the coccinelle script is not in the kernel tree,
then referring to it doesn't mean a whole lot so don't do it. Rather,
explaining why you're doing the change, is a much better thing to do.

Thanks.
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