Re: [Qemu-devel] [PATCH v5 01/11] memory: Sanity check that no listeners remain on a destroyed AddressSpace

[Paolo Bonzini <pbonzini@redhat.com>]

Il 12/03/2014 06:52, Alexey Kardashevskiy ha scritto:
> From: David Gibson <david@gibson.dropbear.id.au>
>
> At the moment, most AddressSpace objects last as long as the guest system
> in practice, but that could well change in future.  In addition, for VFIO
> we will be introducing some private per-AdressSpace information, which must
> be disposed of before the AddressSpace itself is destroyed.
>
> To reduce the chances of subtle bugs in this area, this patch adds
> asssertions to ensure that when an AddressSpace is destroyed, there are no
> remaining MemoryListeners using that AS as a filter.
>
> Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
> ---
>  memory.c | 7 +++++++
>  1 file changed, 7 insertions(+)
>
> diff --git a/memory.c b/memory.c
> index 3f1df23..678661e 100644
> --- a/memory.c
> +++ b/memory.c
> @@ -1722,12 +1722,19 @@ void address_space_init(AddressSpace *as, MemoryRegion *root, const char *name)
>
>  void address_space_destroy(AddressSpace *as)
>  {
> +    MemoryListener *listener;
> +
>      /* Flush out anything from MemoryListeners listening in on this */
>      memory_region_transaction_begin();
>      as->root = NULL;
>      memory_region_transaction_commit();
>      QTAILQ_REMOVE(&address_spaces, as, address_spaces_link);
>      address_space_destroy_dispatch(as);
> +
> +    QTAILQ_FOREACH(listener, &memory_listeners, link) {
> +        assert(listener->address_space_filter != as);
> +    }
> +
>      flatview_unref(as->current_map);
>      g_free(as->name);
>      g_free(as->ioeventfds);
>

Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>

An alternative is to add a count of listeners to the address space and 
assert that it is 0.

Paolo