linux-kernel - Re: [patch 3/7 v2] Cleanup efi_enter_virtual

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Message-ID: <20131113155017.GB17248@console-pimps.org>
Date:	Wed, 13 Nov 2013 15:50:17 +0000
From:	Matt Fleming <matt@...sole-pimps.org>
To:	dyoung@...hat.com
Cc:	linux-kernel@...r.kernel.org, linux-efi@...r.kernel.org,
	x86@...nel.org, mjg59@...f.ucam.org, hpa@...or.com,
	James.Bottomley@...senPartnership.com, vgoyal@...hat.com,
	ebiederm@...ssion.com, horms@...ge.net.au,
	kexec@...ts.infradead.org, bp@...en8.de
Subject: Re: [patch 3/7 v2] Cleanup efi_enter_virtual_mode function

On Tue, 05 Nov, at 04:20:10PM, dyoung@...hat.com wrote:
> Add two small functions:
> efi_merge_regions and efi_map_regions, efi_enter_virtual_mode
> calls them instead of embedding two long for loop.
> 
> v1->v2:
> refresh; coding style fixes.
> 
> Signed-off-by: Dave Young <dyoung@...hat.com>
> ---
>  arch/x86/platform/efi/efi.c |  107 +++++++++++++++++++++++++-------------------
>  1 file changed, 63 insertions(+), 44 deletions(-)

[...]

> @@ -860,17 +840,59 @@ void __init efi_enter_virtual_mode(void)
>  			efi.systab = (efi_system_table_t *) (unsigned long) systab;
>  		}
>  
> -		new_memmap = krealloc(new_memmap,
> -				      (count + 1) * memmap.desc_size,
> -				      GFP_KERNEL);
> -		if (!new_memmap)
> +		*new_memmap = krealloc(*new_memmap,
> +					(*count + 1) * memmap.desc_size,
> +					GFP_KERNEL);
> +		if (!*new_memmap)
>  			goto err_out;
>  
> -		memcpy(new_memmap + (count * memmap.desc_size), md,
> +		memcpy(*new_memmap + (*count * memmap.desc_size), md,
>  		       memmap.desc_size);
> -		count++;
> +		(*count)++;
>  	}
>  
> +err_out:
> +	pr_err("Error reallocating memory, EFI runtime non-functional!\n");
> +}

You should really return an error value here so that we don't
dereference 'new_memmap' below if it's NULL. In fact, just return the
memmap...

> +
> +	efi_merge_regions();
> +
> +	efi_map_regions(&new_memmap, &count);
> +

and make sure to check the return value here.

-- 
Matt Fleming, Intel Open Source Technology Center
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