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

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Date:	Thu, 14 Nov 2013 09:39:55 +0800
From:	Dave Young <dyoung@...hat.com>
To:	Matt Fleming <matt@...sole-pimps.org>
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 11/13/13 at 03:50pm, Matt Fleming wrote:
> 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...

Good catch, will do

> 
> > +
> > +	efi_merge_regions();
> > +
> > +	efi_map_regions(&new_memmap, &count);
> > +
> 
> and make sure to check the return value here.

Ok.

> -- 
> Matt Fleming, Intel Open Source Technology Center
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