From 2b647668c9092dbc26e36a2ece9647cc2f00e05b Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Fri, 17 May 2013 12:40:44 +0200 Subject: [PATCH] memory: avoid ref/unref in memory_region_find Do the entire lookup under RCU, which avoids atomic operations in flatview_ref and flatview_unref. Reviewed-by: Fam Zheng Signed-off-by: Paolo Bonzini --- memory.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/memory.c b/memory.c index a844ced6ef..9b91243978 100644 --- a/memory.c +++ b/memory.c @@ -1828,11 +1828,11 @@ 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); - return ret; + goto out; } while (fr > view->ranges && addrrange_intersects(fr[-1].addr, range)) { @@ -1849,8 +1849,8 @@ MemoryRegionSection memory_region_find(MemoryRegion *mr, ret.offset_within_address_space = int128_get64(range.start); ret.readonly = fr->readonly; memory_region_ref(ret.mr); - - flatview_unref(view); +out: + rcu_read_unlock(); return ret; }