On Wed, 18 Mar 2026 14:53:23 -0600 Alex Williamson <[email protected]> wrote:
> On Tue, 17 Mar 2026 10:44:02 +0530 > <[email protected]> wrote: > > > From: Manish Honap <[email protected]> > > > > C does not permit an initialiser expression on a variable-length array > > (C99 Section 6.7.9 constraint: "The type of the entity to be initialized > > shall not be a variable length array type"). > > > > vfio_pci_irq_set() declared: > > > > u8 buf[sizeof(struct vfio_irq_set) + sizeof(int) * count] = {}; > > > > where `count` is a runtime function parameter, making `buf` a VLA. > > > > GCC rejects this with (tried with GCC-9.4.0): > > > > error: variable-sized object may not be initialized > > > > Fix by removing the `= {}` initialiser and inserting an explicit > > memset() immediately after the declaration. memset() on a VLA is > > perfectly legal and achieves the same zero-initialisation on all > > conforming C implementations. > > > > Fixes: 19faf6fd969c ("vfio: selftests: Add a helper library for VFIO > > selftests") > > Cc: [email protected] > > Reviewed-by: Dave Jiang <[email protected]> > > Reviewed-by: David Matlack <[email protected]> > > Signed-off-by: Manish Honap <[email protected]> > > --- > > > > This fix is self-contained: it touches only the existing vfio selftest > > helper library and carries no dependency on any other patch. It was > > originally included as PATCH 20/20 in the CXL Type-2 VFIO passthrough > > RFC series [1] but belongs on the vfio list independently, as noted by > > Dave Jiang. > > > > [1] https://lore.kernel.org/all/[email protected]/ > > > > tools/testing/selftests/vfio/lib/vfio_pci_device.c | 4 +++- > > 1 file changed, 3 insertions(+), 1 deletion(-) > > > > diff --git a/tools/testing/selftests/vfio/lib/vfio_pci_device.c > > b/tools/testing/selftests/vfio/lib/vfio_pci_device.c > > index fac4c0ecadef..3258e814f450 100644 > > --- a/tools/testing/selftests/vfio/lib/vfio_pci_device.c > > +++ b/tools/testing/selftests/vfio/lib/vfio_pci_device.c > > @@ -26,8 +26,10 @@ > > static void vfio_pci_irq_set(struct vfio_pci_device *device, > > u32 index, u32 vector, u32 count, int *fds) > > { > > - u8 buf[sizeof(struct vfio_irq_set) + sizeof(int) * count] = {}; > > + u8 buf[sizeof(struct vfio_irq_set) + sizeof(int) * count]; > > struct vfio_irq_set *irq = (void *)&buf; > > + > > + memset(buf, 0, sizeof(buf)); > > int *irq_fds = (void *)&irq->data; > > > > irq->argsz = sizeof(buf); > > -- > > 2.25.1 > > > > This unnecessarily split the declaration block. Without objection, > I'll commit this with the following change: > > diff --git a/tools/testing/selftests/vfio/lib/vfio_pci_device.c > b/tools/testing/selftests/vfio/lib/vfio_pci_device.c > index d306ab81123a..fc75e04ef010 100644 > --- a/tools/testing/selftests/vfio/lib/vfio_pci_device.c > +++ b/tools/testing/selftests/vfio/lib/vfio_pci_device.c > @@ -32,9 +32,9 @@ static void vfio_pci_irq_set(struct vfio_pci_device *device, > { > u8 buf[sizeof(struct vfio_irq_set) + sizeof(int) * count]; > struct vfio_irq_set *irq = (void *)&buf; > + int *irq_fds = (void *)&irq->data; > > memset(buf, 0, sizeof(buf)); > - int *irq_fds = (void *)&irq->data; > > irq->argsz = sizeof(buf); > irq->flags = VFIO_IRQ_SET_ACTION_TRIGGER; Applied with this fix to vfio next branch for v7.1. Thanks, Alex
