From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:60793) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UsdOT-0006LD-9u for qemu-devel@nongnu.org; Fri, 28 Jun 2013 14:27:39 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1UsdOR-0000T8-9i for qemu-devel@nongnu.org; Fri, 28 Jun 2013 14:27:37 -0400 Received: from mail-ea0-x22b.google.com ([2a00:1450:4013:c01::22b]:34831) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UsdOR-0000So-2B for qemu-devel@nongnu.org; Fri, 28 Jun 2013 14:27:35 -0400 Received: by mail-ea0-f171.google.com with SMTP id m14so1213658eaj.30 for ; Fri, 28 Jun 2013 11:27:34 -0700 (PDT) Received: from playground.lan (net-37-116-217-184.cust.dsl.vodafone.it. [37.116.217.184]) by mx.google.com with ESMTPSA id o5sm12035344eef.5.2013.06.28.11.27.32 for (version=TLSv1.2 cipher=RC4-SHA bits=128/128); Fri, 28 Jun 2013 11:27:33 -0700 (PDT) Sender: Paolo Bonzini From: Paolo Bonzini Date: Fri, 28 Jun 2013 20:26:38 +0200 Message-Id: <1372444009-11544-20-git-send-email-pbonzini@redhat.com> In-Reply-To: <1372444009-11544-1-git-send-email-pbonzini@redhat.com> References: <1372444009-11544-1-git-send-email-pbonzini@redhat.com> Subject: [Qemu-devel] [PATCH 19/30] memory: avoid ref/unref in memory_region_find List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Do the entire lookup under RCU. Signed-off-by: Paolo Bonzini --- memory.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/memory.c b/memory.c index 7a4fe37..4fc23a2 100644 --- a/memory.c +++ b/memory.c @@ -1559,7 +1559,8 @@ MemoryRegionSection memory_region_find(MemoryRegion *mr, as = memory_region_to_address_space(root); range = addrrange_make(int128_make64(addr), int128_make64(size)); - view = address_space_get_flatview(as); + rcu_read_lock(); + view = rcu_dereference(&as->current_map); fr = flatview_lookup(view, range); if (!fr) { return ret; @@ -1580,7 +1581,7 @@ MemoryRegionSection memory_region_find(MemoryRegion *mr, ret.readonly = fr->readonly; memory_region_ref(ret.mr); - flatview_unref(view); + rcu_read_unlock(); return ret; } -- 1.8.1.4