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

[Peter Lieven <pl@kamp.de>]

Am 25.08.2014 um 17:09 schrieb 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 <pl@kamp.de>
>> ---
>>  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.
>

Good point. What would be the right exit if we receive a NULL from
bitmap_try_new? abort() ?

Peter