Re: [PATCH kernel v5 14/20] powerpc/powernv/npu: Add compound IOMMU groups

On 19/12/2018 11:17, Michael Ellerman wrote:

Alexey Kardashevskiy [off-list ref] writes:

quoted

diff --git a/arch/powerpc/platforms/powernv/npu-dma.c b/arch/powerpc/platforms/powernv/npu-dma.c
index dc629ee..3468eaa 100644
--- a/arch/powerpc/platforms/powernv/npu-dma.c
+++ b/arch/powerpc/platforms/powernv/npu-dma.c

@@ -372,8 +358,263 @@ struct npu {

...

quoted

+
+static void pnv_comp_attach_table_group(struct npu_comp *npucomp,
+		struct pnv_ioda_pe *pe)
+{
+	if (WARN_ON(npucomp->pe_num == NV_NPU_MAX_PE_NUM))
+		return;
+
+	npucomp->pe[npucomp->pe_num] = pe;
+	++npucomp->pe_num;
+}
+
+struct iommu_table_group *pnv_try_setup_npu_table_group(struct pnv_ioda_pe *pe)
+{
+	struct iommu_table_group *table_group;
+	struct npu_comp *npucomp;
+	struct pci_dev *gpdev = NULL;
+	struct pci_controller *hose;
+	struct pci_dev *npdev;
+
+	list_for_each_entry(gpdev, &pe->pbus->devices, bus_list) {
+		npdev = pnv_pci_get_npu_dev(gpdev, 0);
+		if (npdev)
+			break;
+	}
+
+	if (!npdev)
+		/* It is not an NPU attached device, skip */
+		return NULL;

This breaks some configs with:

  arch/powerpc/platforms/powernv/npu-dma.c:550:5: error: 'npdev' may be used uninitialized in this function [-Werror=uninitialized]

gcc 5, 7 and 8 do not warn about this, I have to disable
list_for_each_entry() above to recreate this.

I even compiled gcc 5.5 which some of your buildmachines use and yet no
error on this:

make O=/home/aik/pbuild/kernel-le/ KCFLAGS=-Werror=all ARCH=powerpc
CROSS_COMPILE=/opt/cross/gcc-powerpc64le-linux-5.5.0-nolibc/bin/powerpc64le-linux-
arch/powerpc/platforms/powernv/npu-dma.o



I only get an error when I do:

@@ -525,6 +525,7 @@ struct iommu_table_group

*pnv_try_setup_npu_table_group(struct pnv_ioda_pe *pe)
        struct pci_controller *hose;
        struct pci_dev *npdev;

+       if (0)
        list_for_each_entry(gpdev, &pe->pbus->devices, bus_list) {

                npdev = pnv_pci_get_npu_dev(gpdev, 0);
                if (npdev)



How do you compile?


-- 
Alexey