Sat, Oct 22, 2016 at 03:48:48AM CEST, torvalds@linux-foundation.org wrote:

On Fri, Oct 21, 2016 at 9:31 AM, Jiri Pirko [off-list ref] wrote:

quoted

I don't see how vlan could be used uninitialized. But I understand that
this is impossible for gcc to track it. Please just use uninitialized_var()

Actually, I think we should never use "uninitialized_var()" except
possibly for arrays or structures that gcc can complain about.

It's a horrible thing to use, in that it adds extra cruft to the
source code, and then shuts up a compiler warning (even the _reliable_
warnings from gcc).

It's much better to just initialize the variable, and if gcc some day
gets smarter and sees that it  is unnecessary and always overwritten,
so much the better. The cost of initializing a single word is
basically zero.

On the other hand, I would agrue that initializing a var to "some" value
that is never used might confuse the reader. He would naturally try to
understand the reason for that exact value in initialization.