Re: Build regressions/improvements in v3.10-rc6

From: Michael Ellerman
Date: Tue Jun 18 2013 - 00:54:58 EST


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
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