Re: [Qemu-devel] [PATCH 1/2] util: introduce bitmap_try_new

[Eric Blake]

On 08/22/2014 03:26 AM, Peter Lieven wrote:
> regular bitmap_new simply aborts if the memory allocation fails.
> bitmap_try_new returns NULL on failure and allows for proper
> error handling.
> 
> Signed-off-by: Peter Lieven <address@hidden>
> ---
>  include/qemu/bitmap.h |    6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/include/qemu/bitmap.h b/include/qemu/bitmap.h
> index 1babd5d..51b430f 100644
> --- a/include/qemu/bitmap.h
> +++ b/include/qemu/bitmap.h
> @@ -94,6 +94,12 @@ static inline unsigned long *bitmap_new(long nbits)
>      return g_malloc0(len);
>  }
>  
> +static inline unsigned long *bitmap_try_new(long nbits)
> +{
> +    long len = BITS_TO_LONGS(nbits) * sizeof(unsigned long);
> +    return g_try_malloc0(len);
> +}
> +

What you have works, but I personally would have reimplemented
bitmap_new as the first caller of bitmap_try_new in this patch, where
bitmap_new handles a NULL bitmap_try_new return by abort()ing, so that
it has the same behavior.  By routing the one function to use the other,
we are future-proofing: if initialization of a bitmap ever needs
modification, we only update bitmap_try_new, rather than copying the
updates to both functions.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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