Re: [GIT PULL] kbuild updates for v4.7-rc1

From: Linus Torvalds
Date: Fri May 27 2016 - 01:27:07 EST

On Thu, May 26, 2016 at 1:33 PM, Michal Marek <mmarek@xxxxxxxx> wrote:
> git:// kbuild

This pull results in new warnings.

I get new "may be uninitialized" warnings now for me allmodconfig
build, and while I didn't look at them all, the one I looked at was
just entirely crap:

fs/gfs2/dir.c: In function âdir_split_leaf.isra.16â:
fs/gfs2/dir.c:1021:8: warning: âleaf_noâ may be used uninitialized
in this function [-Wmaybe-uninitialized]
error = get_leaf(dip, leaf_no, &obh);

yeah no, leaf_no is initialized a few lines up by

error = get_leaf_nr(dip, index, &leaf_no);

and the fact that gcc can't follow the trivial error handling is not
our fault. It looks *so* trivial that I wonder why.

That said, I don't see exactly what in the pull request causes this.

My reading of the diff seems to say that you are actually adding
*more* cases of -Wno-maybe-uninitialized, not less.

So I suspect it's almost accidental in just how the Kconfig option
CC_OPTIMIZE_FOR_PERFORMANCE happened, which in turn probably just
changes the options for "make allmiodconfig", and it now picks a
non-size-optimized build that always showed those warnings and I just
didn't see them.

Annoying. I've pulled it, but I wish you would look at this.