Build regressions/improvements in v3.10-rc6

[Michael Ellerman]

On Mon, Jun 17, 2013 at 09:19:51PM +0200, Geert Uytterhoeven wrote:
> On Mon, 17 Jun 2013, Geert Uytterhoeven wrote:
> 
> powerpc-randconfig

>   + arch/powerpc/include/asm/mmu-hash64.h: error: control reaches end of non-void function [-Werror=return-type]:  => 180:1

This is running past a BUG(), which must mean we have CONFIG_BUG=n.
BUG() turning into nothing is a bug in the CONFIG_BUG=n implementation IMHO.
There was a discussion about this recently, I didn't see what the resolution
was.

>   + arch/powerpc/kvm/book3s_hv.c: error: 'vcpus_to_update[need_vpa_update]' may be used uninitialized in this function [-Werror=uninitialized]:  => 1187:22

This looks bogus to me:

  if (need_vpa_update) {
 	spin_unlock(&vc->lock);
 	for (i = 0; i < need_vpa_update; ++i) 
 		kvmppc_update_vpas(vcpus_to_update[i]);

I fail to see how that accesses vcpus_to_update[need_vpa_update].

>   + arch/powerpc/platforms/cell/beat_iommu.c: error: 'dma_base' may be used uninitialized in this function [-Werror=uninitialized]:  => 69:11
>   + arch/powerpc/platforms/cell/beat_iommu.c: error: 'dma_size' may be used uninitialized in this function [-Werror=uninitialized]:  => 68:2
>   + arch/powerpc/platforms/cell/beat_iommu.c: error: 'io_page_size' may be used uninitialized in this function [-Werror=uninitialized]:  => 68:54
>   + arch/powerpc/platforms/cell/beat_wrapper.h: error: 'io_space_id' may be used uninitialized in this function [-Werror=uninitialized]:  => 249:2
>   + arch/powerpc/platforms/cell/beat_wrapper.h: error: 'ioid' may be used uninitialized in this function [-Werror=uninitialized]:  => 249:2

The above are all false warnings AFAICS.

> We need more randconfig builds to divert attention from powerpc ;-)

Or we could just drop them, with all the false positives from -Wuninitialized
it's hard to spot any real problems.

cheers