On 11/14/2011 12:07 PM, Avi Kivity wrote:
> On 11/14/2011 11:23 AM, Takuya Yoshikawa wrote:
> > Needed for the next patch which uses this number to decide how to write
> > protect a slot.
> >
> > /* If nothing is dirty, don't bother messing with page tables. */
> > - if (is_dirty) {
> > + if (memslot->nr_dirty_pages) {
> > struct kvm_memslots *slots, *old_slots;
> > unsigned long *dirty_bitmap;
> >
> > @@ -3504,6 +3500,7 @@ int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm,
> > goto out;
> > memcpy(slots, kvm->memslots, sizeof(struct kvm_memslots));
> > slots->memslots[log->slot].dirty_bitmap = dirty_bitmap;
> > + slots->memslots[log->slot].nr_dirty_pages = 0;
> > slots->generation++;
> >
> > #endif /* !CONFIG_S390 */
> > @@ -1491,7 +1492,8 @@ void mark_page_dirty_in_slot(struct kvm *kvm, struct
> > kvm_memory_slot *memslot,
> > if (memslot && memslot->dirty_bitmap) {
> > unsigned long rel_gfn = gfn - memslot->base_gfn;
> >
> > - __set_bit_le(rel_gfn, memslot->dirty_bitmap);
> > + if (!__test_and_set_bit_le(rel_gfn, memslot->dirty_bitmap))
> > + memslot->nr_dirty_pages++;
> > }
> > }
> >
>
> The two assignments to ->nr_dirty_pages can race, no? Nothing protects it.
>
er, it can't, it's before the rcu_assign_pointer().
--
error compiling committee.c: too many argumen
ts to function
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