Messages in this thread | | | Subject | Re: [PATCH v3 05/11] KVM: page track: introduce kvm_page_track_{add,remove}_page | From | Paolo Bonzini <> | Date | Fri, 19 Feb 2016 12:37:16 +0100 |
| |
On 14/02/2016 12:31, Xiao Guangrong wrote: > + /* does tracking count wrap? */ > + WARN_ON((count > 0) && (val + count < val));
This doesn't work, because "val + count" is an int.
> + /* the last tracker has already gone? */ > + WARN_ON((count < 0) && (val < !count));
Also, here any underflow should warn.
You can actually use the fact that val + count is an int like this:
WARN_ON(val + count < 0 || val + count > USHRT_MAX)
and also please return if the warning fires.
> +void kvm_page_track_add_page(struct kvm *kvm, gfn_t gfn, > + enum kvm_page_track_mode mode) > +{ > + struct kvm_memslots *slots; > + struct kvm_memory_slot *slot; > + int i; > + > + for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) { > + slots = __kvm_memslots(kvm, i); > + > + slot = __gfn_to_memslot(slots, gfn); > + if (!slot) > + continue; > + > + spin_lock(&kvm->mmu_lock); > + kvm_slot_page_track_add_page_nolock(kvm, slot, gfn, mode); > + spin_unlock(&kvm->mmu_lock); > + } > +}
I don't think it is right to walk all address spaces. The good news is that you're not using kvm_page_track_{add,remove}_page at all as far as I can see, so you can just remove them.
Also, when you will need it, I think it's better to move the spin_lock/spin_unlock pair outside the for loop. With this change, perhaps it's better to leave it to the caller completely---but I cannot say until I see the caller.
In the meanwhile, please leave out _nolock from the other functions' name.
Paolo
| |