On Mon, Jun 16, 2014 at 04:50:51PM +0200, Stephan Gabert wrote:
> As mentioned in net/core/dev.c register_netdev() explicitly returns a
> negative errno code on failure.
>
> So in case of failure, one should rather test whether ret is negative
> than just unlike 0.
No. In the kernel the normal way is to say:
if (ret)
return ret;
Zero is succes and non-zero is error code.
if (ret != 0)
return ret;
That's a double negative and pointlessly confusing.
if (ret != 0 != 0 != 0)
That's a hextuple negative and awesomely confusing.
There are times where a double negative is ok. When you are talking
about numbers specifically:
if (ret != 0 && ret != 3) {
That means ret is not zero or three, but zero doesn't mean success or
failure, it's just a number.
For strcmp() functions you should always compare against zero
because that is the idiom.
if (strcmp(foo, bar) < 0)
if (strcmp(foo, bar) != 0)
The first "<" means "foo" is before "bar" and "!=" means not equal.
if (ret < 0)
return ret;
Probably means that now ret is either zero or a positive value??? It is
ambiguous.
regards,
dan carpenter
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