libxl: events: STATE_AO_GC checks ao is still valid

This will catch earlier the mistake where an ao is completed while it
still has events registered: when the event callback happens for the
long-gone ao, we will crash before attempting to execute any of the
operation-specific code.

Signed-off-by: Ian Jackson <ian.jackson@eu.citrix.com>
Committed-by: Ian Campbell <ian.campbell@citrix.com>

1 files changed, 7 insertions, 0 deletions

diff --git a/tools/libxl/libxl_event.c b/tools/libxl/libxl_event.c
index 03d0498020..350e846aa4 100644
--- a/tools/libxl/libxl_event.c
+++ b/tools/libxl/libxl_event.c
@@ -1352,6 +1352,13 @@ void libxl__ao_abort(libxl__ao *ao)
     libxl__ao__destroy(CTX, ao);
 }
 
+libxl__gc *libxl__ao_inprogress_gc(libxl__ao *ao)
+{
+    assert(ao->magic == LIBXL__AO_MAGIC);
+    assert(!ao->complete);
+    return &ao->gc;
+}
+
 void libxl__ao_complete(libxl__egc *egc, libxl__ao *ao, int rc)
 {
     assert(ao->magic == LIBXL__AO_MAGIC);