Re: [PATCH V8 12/39] memory: flat section iterator

[Peng Liang]

On 6/15/2022 10:51 PM, Steve Sistare wrote:
> Add an iterator over the sections of a flattened address space.
> 
> Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
> Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
> ---
>  include/exec/memory.h | 31 +++++++++++++++++++++++++++++++
>  softmmu/memory.c      | 20 ++++++++++++++++++++
>  2 files changed, 51 insertions(+)
> 
> diff --git a/include/exec/memory.h b/include/exec/memory.h
> index a03301d..6a257a4 100644
> --- a/include/exec/memory.h
> +++ b/include/exec/memory.h
> @@ -2343,6 +2343,37 @@ void 
> memory_region_set_ram_discard_manager(MemoryRegion *mr,
>                                             RamDiscardManager *rdm);
>  
>  /**
> + * memory_region_section_cb: callback for 
> address_space_flat_for_each_section()
> + *
> + * @mrs: MemoryRegionSection of the range
> + * @opaque: data pointer passed to address_space_flat_for_each_section()
> + * @errp: error message, returned to the address_space_flat_for_each_section
> + *        caller.
> + *
> + * Returns: non-zero to stop the iteration, and 0 to continue.  The same
> + * non-zero value is returned to the address_space_flat_for_each_section 
> caller.
> + */
> +
> +typedef int (*memory_region_section_cb)(MemoryRegionSection *mrs,
> +                                        void *opaque,
> +                                        Error **errp);
> +
> +/**
> + * address_space_flat_for_each_section: walk the ranges in the address space
> + * flat view and call @func for each.  Return 0 on success, else return 
> non-zero
> + * with a message in @errp.
> + *
> + * @as: target address space
> + * @func: callback function
> + * @opaque: passed to @func
> + * @errp: passed to @func
> + */
> +int address_space_flat_for_each_section(AddressSpace *as,
> +                                        memory_region_section_cb func,
> +                                        void *opaque,
> +                                        Error **errp);
> +
> +/**
>   * memory_region_find: translate an address/size relative to a
>   * MemoryRegion into a #MemoryRegionSection.
>   *
> diff --git a/softmmu/memory.c b/softmmu/memory.c
> index 0fe6fac..e5aefdd 100644
> --- a/softmmu/memory.c
> +++ b/softmmu/memory.c
> @@ -2683,6 +2683,26 @@ bool memory_region_is_mapped(MemoryRegion *mr)
>      return !!mr->container || mr->mapped_via_alias;
>  }
>  
> +int address_space_flat_for_each_section(AddressSpace *as,
> +                                        memory_region_section_cb func,
> +                                        void *opaque,
> +                                        Error **errp)
> +{
> +    FlatView *view = address_space_get_flatview(as);
> +    FlatRange *fr;
> +    int ret;
> +
> +    FOR_EACH_FLAT_RANGE(fr, view) {
> +        MemoryRegionSection mrs = section_from_flat_range(fr, view);
> +        ret = func(&mrs, opaque, errp);
> +        if (ret) {
> +            return ret;
> +        }
> +    }
> +

Hi Steve,
I guess a flatview_unref(view) is missing here? Because the return value
of address_space_get_flatview has been flatview_ref.

> +    return 0;
> +}
> +
>  /* Same as memory_region_find, but it does not add a reference to the
>   * returned region.  It must be called from an RCU critical section.
>   */