On 13/10/17 12:57, Christoffer Dall wrote: > On Fri, Oct 13, 2017 at 12:00:50PM +0100, Marc Zyngier wrote: >> On 13/10/17 11:52, Christoffer Dall wrote: >>> We currently allocate an entry dynamically, but we never check if the >>> allocation actually succeeded. We actually don't need a dynamic >>> allocation, because we know the maximum size of an ITS table entry, so >>> we can simply use an allocation on the stack. >>> >>> Cc: <stable@xxxxxxxxxxxxxxx> >>> Signed-off-by: Christoffer Dall <christoffer.dall@xxxxxxxxxx> >>> --- >>> virt/kvm/arm/vgic/vgic-its.c | 19 ++++++++----------- >>> 1 file changed, 8 insertions(+), 11 deletions(-) >>> >>> diff --git a/virt/kvm/arm/vgic/vgic-its.c b/virt/kvm/arm/vgic/vgic-its.c >>> index f51c1e1..555f42f 100644 >>> --- a/virt/kvm/arm/vgic/vgic-its.c >>> +++ b/virt/kvm/arm/vgic/vgic-its.c >>> @@ -176,6 +176,7 @@ static const struct vgic_its_abi its_table_abi_versions[] = { >>> }; >>> >>> #define NR_ITS_ABIS ARRAY_SIZE(its_table_abi_versions) >>> +#define MAX_ENTRY_SIZE 8 /* Max Entry size across all ABI versions */ >>> >>> inline const struct vgic_its_abi *vgic_its_get_abi(struct vgic_its *its) >>> { >>> @@ -1801,37 +1802,33 @@ typedef int (*entry_fn_t)(struct vgic_its *its, u32 id, void *entry, >>> static int scan_its_table(struct vgic_its *its, gpa_t base, int size, int esz, >>> int start_id, entry_fn_t fn, void *opaque) >>> { >>> - void *entry = kzalloc(esz, GFP_KERNEL); >>> struct kvm *kvm = its->dev->kvm; >>> unsigned long len = size; >>> int id = start_id; >>> gpa_t gpa = base; >>> + char entry[MAX_ENTRY_SIZE]; >> >> Nit: you can drop the memset below if you initialize immediately, and >> GCC supporting dynamic arrays allows you to write this: >> >> char entry[esz] = { 0, }; >> >> so that you don't have to add the MAX_ENTRY_SIZE. >> > > Using a dynamic sized array is a great idea, but trying to initalize it > at the same time gives me: > > error: variable-sized object may not be initialized > > Is there a trick I'm unfamiliar with? No, it is just that these two things are mutually incompatible, and I didn't realize it. You have to choose one or the other... :-( I suggest you keep the memset... Thanks, M. -- Jazz is not dead. It just smells funny...