Re: [Xen-devel] [PATCH V3 3/8] xen: Delay m2p_override initialization

From: David Vrabel <david.vrabel@citrix.com>
To: Juergen Gross <jgross@suse.com>, <linux-kernel@vger.kernel.org>,
	<xen-devel@lists.xensource.com>, <konrad.wilk@oracle.com>,
	<david.vrabel@citrix.com>, <boris.ostrovsky@oracle.com>,
	<x86@kernel.org>, <tglx@linutronix.de>, <mingo@redhat.com>,
	<hpa@zytor.com>
Subject: Re: [Xen-devel] [PATCH V3 3/8] xen: Delay m2p_override initialization
Date: Tue, 11 Nov 2014 10:29:32 +0000	[thread overview]
Message-ID: <5461E50C.4040309@citrix.com> (raw)
In-Reply-To: <1415684626-18590-4-git-send-email-jgross@suse.com>

On 11/11/14 05:43, Juergen Gross wrote:
> The m2p overrides are used to be able to find the local pfn for a
> foreign mfn mapped into the domain. They are used by driver backends
> having to access frontend data.
> 
> As this functionality isn't used in early boot it makes no sense to
> initialize the m2p override functions very early. It can be done
> later without doing any harm, removing the need for allocating memory
> via extend_brk().
> 
> While at it make some m2p override functions static as they are only
> used internally.

Reviewed-by: David Vrabel <david.vrabel@citrix.com>

But...

>  static struct page *m2p_find_override(unsigned long mfn)
>  {
>  	unsigned long flags;
> -	struct list_head *bucket = &m2p_overrides[mfn_hash(mfn)];
> +	struct list_head *bucket;
>  	struct page *p, *ret;

    if (unlikely(!m2p_overrides))
        return NULL;

Would be preferred,

David