On Wed, Aug 29, 2018 at 01:12:05PM +0300, Dan Carpenter wrote: > On Wed, Aug 29, 2018 at 12:05:06PM +0300, Liran Alon wrote: > > > arch/x86/kvm/lapic.c | 17 +++++++++++++---- > > > 1 file changed, 13 insertions(+), 4 deletions(-) > > > > > > diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c > > > index 0cefba2..86e933c 100644 > > > --- a/arch/x86/kvm/lapic.c > > > +++ b/arch/x86/kvm/lapic.c > > > @@ -571,18 +571,27 @@ int kvm_pv_send_ipi(struct kvm *kvm, unsigned long ipi_bitmap_low, > > > rcu_read_lock(); > > > map = rcu_dereference(kvm->arch.apic_map); > > > > > > + if (unlikely((s32)(map->max_apic_id - __fls(ipi_bitmap_low)) < min)) > > > + goto out; > > > > I personally think “if ((min + __fls(ipi_bitmap_low)) > map->max_apic_id)” is more readable. > > But that’s just a matter of taste :) > > That's an integer overflow. > > But I do prefer to put the variable on the left. The truth is that some > Smatch checks just ignore code which is backwards written because > otherwise you have to write duplicate code and the most code is written > with the variable on the left. > > if (min > (s32)(map->max_apic_id - __fls(ipi_bitmap_low)) Wait, the (s32) cast doesn't make sense. We want negative min values to be treated as invalid. regards, dan carpenter
