From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:57280) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZhZig-0001n7-Ll for qemu-devel@nongnu.org; Thu, 01 Oct 2015 05:00:10 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZhZid-0002lf-EC for qemu-devel@nongnu.org; Thu, 01 Oct 2015 05:00:06 -0400 Received: from mx1.redhat.com ([209.132.183.28]:54789) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZhZic-0002ji-Uo for qemu-devel@nongnu.org; Thu, 01 Oct 2015 05:00:03 -0400 From: Markus Armbruster Date: Thu, 1 Oct 2015 10:59:50 +0200 Message-Id: <1443689999-12182-2-git-send-email-armbru@redhat.com> In-Reply-To: <1443689999-12182-1-git-send-email-armbru@redhat.com> References: <1443689999-12182-1-git-send-email-armbru@redhat.com> Subject: [Qemu-devel] [PATCH v5 01/10] memory: allow destroying a non-empty MemoryRegion List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: thuth@redhat.com, ehabkost@redhat.com, stefanha@redhat.com, pbonzini@redhat.com, afaerber@suse.de From: Paolo Bonzini This is legal; the MemoryRegion will simply unreference all the existing subregions and possibly bring them down with it as well. However, it requires a bit of care to avoid an infinite loop. Finalizing a memory region cannot trigger an address space update, but memory_region_del_subregion errs on the side of caution and might trigger a spurious update: avoid that by resetting mr->enabled first. Signed-off-by: Paolo Bonzini Message-Id: <1443530263-32340-2-git-send-email-pbonzini@redhat.com> Signed-off-by: Markus Armbruster --- memory.c | 17 ++++++++++++++++- 1 file changed, 16 insertions(+), 1 deletion(-) diff --git a/memory.c b/memory.c index ef87363..73d28ba 100644 --- a/memory.c +++ b/memory.c @@ -1304,7 +1304,22 @@ static void memory_region_finalize(Object *obj) { MemoryRegion *mr = MEMORY_REGION(obj); - assert(QTAILQ_EMPTY(&mr->subregions)); + assert(!mr->container); + + /* We know the region is not visible in any address space (it + * does not have a container and cannot be a root either because + * it has no references, so we can blindly clear mr->enabled. + * memory_region_set_enabled instead could trigger a transaction + * and cause an infinite loop. + */ + mr->enabled = false; + memory_region_transaction_begin(); + while (!QTAILQ_EMPTY(&mr->subregions)) { + MemoryRegion *subregion = QTAILQ_FIRST(&mr->subregions); + memory_region_del_subregion(mr, subregion); + } + memory_region_transaction_commit(); + mr->destructor(mr); memory_region_clear_coalescing(mr); g_free((char *)mr->name); -- 2.4.3