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memory: allow destroying a non-empty MemoryRegion

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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 <pbonzini@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <1443689999-12182-2-git-send-email-armbru@redhat.com>
This commit is contained in:
Paolo Bonzini 2015-10-01 10:59:50 +02:00 committed by Markus Armbruster
parent c6047e9621
commit 2e2b8eb70f
1 changed files with 16 additions and 1 deletions
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17
memory.c
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@ -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);