Re: [Xen-devel] [PATCH 2/2] m2p_find_override: use list_for_each_entry_safe

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

On Tue, Mar 27, 2012 at 02:52:44PM +0100, Stefano Stabellini wrote:
> Use list_for_each_entry_safe and remove the spin_lock acquisition in
> m2p_find_override.

So this would allow us to get stale entries. Is that OK?

> 
> Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
> ---
>  arch/x86/xen/p2m.c |    8 ++------
>  1 files changed, 2 insertions(+), 6 deletions(-)
> 
> diff --git a/arch/x86/xen/p2m.c b/arch/x86/xen/p2m.c
> index 1b267e7..7ed8cc3 100644
> --- a/arch/x86/xen/p2m.c
> +++ b/arch/x86/xen/p2m.c
> @@ -809,21 +809,17 @@ struct page *m2p_find_override(unsigned long mfn)
>  {
>       unsigned long flags;
>       struct list_head *bucket = &m2p_overrides[mfn_hash(mfn)];
> -     struct page *p, *ret;
> +     struct page *p, *t, *ret;
>  
>       ret = NULL;
>  
> -     spin_lock_irqsave(&m2p_override_lock, flags);
> -
> -     list_for_each_entry(p, bucket, lru) {
> +     list_for_each_entry_safe(p, t, bucket, lru) {
>               if (page_private(p) == mfn) {
>                       ret = p;
>                       break;
>               }
>       }
>  
> -     spin_unlock_irqrestore(&m2p_override_lock, flags);
> -
>       return ret;
>  }
>  
> -- 
> 1.7.2.5

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