On Thu, 01/22 15:47, Paolo Bonzini wrote:
> Do the entire lookup under RCU, which avoids atomic operations.
address_space_get_flatview() already is RCU protected, I don't see why this
patch is necessary. Could you explain?
And there is one question below:
>
> Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>
> ---
> memory.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/memory.c b/memory.c
> index a844ced..577e87c 100644
> --- a/memory.c
> +++ b/memory.c
> @@ -1828,7 +1828,8 @@ MemoryRegionSection memory_region_find(MemoryRegion *mr,
> }
> range = addrrange_make(int128_make64(addr), int128_make64(size));
>
> - view = address_space_get_flatview(as);
> + rcu_read_lock();
> + view = atomic_rcu_read(&as->current_map);
> fr = flatview_lookup(view, range);
> if (!fr) {
> flatview_unref(view);
Following lines are:
return ret;
}
Which requires a rcu_read_unlock.
Fam
> @@ -1850,7 +1851,7 @@ MemoryRegionSection memory_region_find(MemoryRegion *mr,
> ret.readonly = fr->readonly;
> memory_region_ref(ret.mr);
>
> - flatview_unref(view);
> + rcu_read_unlock();
> return ret;
> }
>
> --
> 1.8.3.1
>
>
