linux-kernel - Re: [PATCH 05/13] x86/microcode/intel: Make _save

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Date:	Tue, 24 Feb 2015 17:22:58 +0100
From:	Quentin Casasnovas <quentin.casasnovas@...cle.com>
To:	Borislav Petkov <bp@...en8.de>
Cc:	X86 ML <x86@...nel.org>, LKML <linux-kernel@...r.kernel.org>,
	Quentin Casasnovas <quentin.casasnovas@...cle.com>
Subject: Re: [PATCH 05/13] x86/microcode/intel: Make _save_mc() return the
 updated saved count

On Tue, Feb 24, 2015 at 11:37:04AM +0100, Borislav Petkov wrote:
> From: Borislav Petkov <bp@...e.de>
> 
> ... of microcode patches instead of handing in a pointer which is used
> for I/O in an otherwise void function.
> 
> Signed-off-by: Borislav Petkov <bp@...e.de>
> ---
>  arch/x86/kernel/cpu/microcode/intel_early.c | 29 ++++++++++++++---------------
>  1 file changed, 14 insertions(+), 15 deletions(-)
> 
> diff --git a/arch/x86/kernel/cpu/microcode/intel_early.c b/arch/x86/kernel/cpu/microcode/intel_early.c
> index ffeac5d62eca..ee74e7726c33 100644
> --- a/arch/x86/kernel/cpu/microcode/intel_early.c
> +++ b/arch/x86/kernel/cpu/microcode/intel_early.c
> @@ -264,17 +264,18 @@ err:
>   * - or if it is a newly discovered microcode patch.
>   *
>   * The microcode patch should have matching model with CPU.
> + *
> + * Returns: The updated number @num_saved of saved microcode patches.
>   */
> -static void _save_mc(struct microcode_intel **mc_saved, u8 *ucode_ptr,
> -		     unsigned int *mc_saved_count_p)
> +static unsigned int _save_mc(struct microcode_intel **mc_saved,
> +			     u8 *ucode_ptr, unsigned int num_saved)
>  {
> -	int i;
> -	int found = 0;
> -	unsigned int mc_saved_count = *mc_saved_count_p;
>  	struct microcode_header_intel *mc_header;
> +	int found = 0, i;
>  
>  	mc_header = (struct microcode_header_intel *)ucode_ptr;
> -	for (i = 0; i < mc_saved_count; i++) {
> +
> +	for (i = 0; i < num_saved; i++) {

Minor comment: since num_saved is unsigned, I think it would be better to
just use an unsigned int for `i` as well.

>  		unsigned int sig, pf;
>  		unsigned int new_rev;
>  		struct microcode_header_intel *mc_saved_header =
> @@ -291,21 +292,20 @@ static void _save_mc(struct microcode_intel **mc_saved, u8 *ucode_ptr,
>  				 * Replace the older one with this newer
>  				 * one.
>  				 */
> -				mc_saved[i] =
> -					(struct microcode_intel *)ucode_ptr;
> +				mc_saved[i] = (struct microcode_intel *)ucode_ptr;
>  				break;
>  			}
>  		}
>  	}
> -	if (i >= mc_saved_count && !found)
> +
> +	if (i >= num_saved && !found)

While at it, I could not find that `i` would ever be bigger than
`num_saved` so maybe you can just test for equality instead?  It just makes
it clearer what the code does.

Quentin
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