From 32f3dd55b9c8c5ce45ac8f90a2a5dd5cfab0f4df Mon Sep 17 00:00:00 2001 From: Nick Desaulniers Date: Sat, 6 Jan 2018 13:39:48 -0800 Subject: [PATCH 2/4] x86: xen: remove the use of VLAIS Variable Length Arrays In Structs (VLAIS) is not supported by Clang, and frowned upon by others. https://lkml.org/lkml/2013/9/23/500 Here, the VLAIS was used because the size of the bitmap returned from xen_mc_entry() depended on possibly (based on kernel configuration) runtime sized data. Rather than declaring args as a VLAIS then calling sizeof on *args, we calculate the appropriate sizeof args manually. Further, we can get rid of the #ifdef's and rely on num_possible_cpus() (thanks to a helpful checkpatch warning from an earlier version of this patch). Suggested-by: Juergen Gross Signed-off-by: Nick Desaulniers Reviewed-by: Juergen Gross Signed-off-by: Boris Ostrovsky --- arch/x86/xen/mmu_pv.c | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-) diff --git a/arch/x86/xen/mmu_pv.c b/arch/x86/xen/mmu_pv.c index 042e9c422b21..854d5aa90b02 100644 --- a/arch/x86/xen/mmu_pv.c +++ b/arch/x86/xen/mmu_pv.c @@ -1325,20 +1325,18 @@ static void xen_flush_tlb_others(const struct cpumask *cpus, { struct { struct mmuext_op op; -#ifdef CONFIG_SMP - DECLARE_BITMAP(mask, num_processors); -#else DECLARE_BITMAP(mask, NR_CPUS); -#endif } *args; struct multicall_space mcs; + const size_t mc_entry_size = sizeof(args->op) + + sizeof(args->mask[0]) * BITS_TO_LONGS(num_possible_cpus()); trace_xen_mmu_flush_tlb_others(cpus, info->mm, info->start, info->end); if (cpumask_empty(cpus)) return; /* nothing to do */ - mcs = xen_mc_entry(sizeof(*args)); + mcs = xen_mc_entry(mc_entry_size); args = mcs.args; args->op.arg2.vcpumask = to_cpumask(args->mask); -- 2.17.0