From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:57341) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZguAW-00035x-TX for qemu-devel@nongnu.org; Tue, 29 Sep 2015 08:38:06 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZguAS-0001vE-Tw for qemu-devel@nongnu.org; Tue, 29 Sep 2015 08:38:04 -0400 From: Paolo Bonzini Date: Tue, 29 Sep 2015 14:37:41 +0200 Message-Id: <1443530263-32340-2-git-send-email-pbonzini@redhat.com> In-Reply-To: <1443530263-32340-1-git-send-email-pbonzini@redhat.com> References: <1443530263-32340-1-git-send-email-pbonzini@redhat.com> Subject: [Qemu-devel] [PATCH 1/3] 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: peter.maydell@linaro.org, mark.cave-ayland@ilande.co.uk, agraf@suse.de, armbru@redhat.com, blauwirbel@gmail.com, qemu-ppc@nongnu.org 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 --- 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); -- 2.5.0