On 11/03/2015 02:57 PM, Jarod Wilson wrote:
> Geert Uytterhoeven wrote:
>> On Tue, Nov 3, 2015 at 11:03 AM, Nikolay Aleksandrov
>> <niko...@cumulusnetworks.com> wrote:
>>> On 11/03/2015 03:55 AM, Jarod Wilson wrote:
>>> [snip]
>>>> +#define for_each_netdev_feature(mask_addr, feature)
>>>> \
>>>> + int bit;
>>>> \
>>>> + for_each_set_bit(bit, (unsigned long *)mask_addr,
>>>> NETDEV_FEATURE_COUNT) \
>>>> + feature = __NETIF_F_BIT(bit);
>>>> +
>>> ^
>>> This is broken, it will not work for more than a single feature.
>>
>> Indeed it is.
>>
>> This is used as:
>>
>> for_each_netdev_feature(&upper_disables, feature) {
>> ...
>> }
>>
>> which expands to:
>>
>> int bit;
>> for_each_set_bit(bit, (unsigned long *)mask_addr,
>> NETDEV_FEATURE_COUNT)
>> feature = __NETIF_F_BIT(bit);
>> {
>> ...
>> }
>>
>> Note the assignment to "feature" happens outside the {}-delimited block.
>> And the block is always executed once.
>
> Bah, crap, I was still staring at the code not seeing it, thank you for the
> detailed cluebat. I'll fix that up right now.
>
Yeah, sorry for not elaborating, I wrote it in a hurry. :-)
Thanks Geert!
By the way since you'll be changing this code, I don't know if it's okay to
declare caller-visible hidden local variables in a macro like this, at the very
least please consider renaming it to something that's much less common, I can
see
"bit" being used here and there. IMO either try to find a way to avoid it
altogether or add another argument to the macro so it's explicitly passed.
Cheers,
Nik
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
