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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: n2LWieUu5AUG6LNyAcwJJHUYf7x2xo+2eFnIg1/FgQUO+mlIzYjPZyRBI1Vmkkr4c4L84YySz45nxDaPQsPRhLLXQnpNGOUgBtyMaNxEk68pr+rbaBOJnSsM+orC7HENdGmHHGFNo9sEXUF9Gg87WRkqX8vGl/93GWOX8RM6ORbgMwdMziJBwuMhKjewj3KWxRqi4u9HW4/HEoSpV1OR1B5J0PHjRAETjPVnmkBsplB5e9M3Uu87Kt9tesNFSURs64fiwOISLtz0urMGM8cpZAIUAlXjxtzqEph05RrWEBzwSjgLIj+CWcW7jnKaCzldrtKnF/TqAezG9p3Y/MT8Snx/dhSSEQcDkDBMFu7PVjB5wFBgkVurhCqd6tzrFOOZNjLSqhKuSUnAfOLyVqs8WBxN8SzVsOxDhwy3NGW4VWgvIt0/xHN4HDE2Vtj9GLxH X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 18 Mar 2026 20:53:51.7542 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: e4f56686-20de-4e88-3868-08de85307619 X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=43083d15-7273-40c1-b7db-39efd9ccc17a;Ip=[216.228.117.160];Helo=[mail.nvidia.com] X-MS-Exchange-CrossTenant-AuthSource: BL6PEPF00020E5F.namprd04.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: DS7PR12MB8290 On Tue, 17 Mar 2026 10:44:02 +0530 wrote: > From: Manish Honap > > 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: stable@vger.kernel.org > Reviewed-by: Dave Jiang > Reviewed-by: David Matlack > Signed-off-by: Manish Honap > --- > > 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/20260311203440.752648-1-mhonap@nvidia.com/ > > 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; Thanks, Alex