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From: Eduardo Habkost <ehabkost@redhat.com>
To: "Paolo Bonzini" <pbonzini@redhat.com>,
	"Marc-André Lureau" <marcandre.lureau@redhat.com>,
	qemu-devel@nongnu.org
Cc: "Daniel P. Berrangé" <berrange@redhat.com>,
	"Eduardo Habkost" <ehabkost@redhat.com>,
	"Philippe Mathieu-Daudé" <f4bug@amsat.org>
Subject: [PATCH 2/2] qom: Assert that objects being destroyed have no parent
Date: Tue, 15 Dec 2020 17:41:33 -0500	[thread overview]
Message-ID: <20201215224133.3545901-3-ehabkost@redhat.com> (raw)
In-Reply-To: <20201215224133.3545901-1-ehabkost@redhat.com>

QOM reference counting bugs are often hard to detect, but there's
one kind of bug that's easier: if we are freeing an object but is
still attached to a parent, it means the reference count is wrong
(because the parent always hold a reference to their children).

Add an assertion to make sure we detect those cases.

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
---
 qom/object.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/qom/object.c b/qom/object.c
index f2ae6e6b2a..5cfed6d7c6 100644
--- a/qom/object.c
+++ b/qom/object.c
@@ -685,6 +685,7 @@ static void object_finalize(void *data)
     object_deinit(obj, ti);
 
     g_assert(obj->ref == 0);
+    g_assert(obj->parent == NULL);
     if (obj->free) {
         obj->free(obj);
     }
-- 
2.28.0



  parent reply	other threads:[~2020-12-15 22:44 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-12-15 22:41 [PATCH 0/2] Fix test-char reference counting bug Eduardo Habkost
2020-12-15 22:41 ` [PATCH 1/2] test-char: Destroy chardev correctly at char_file_test_internal() Eduardo Habkost
2020-12-16  7:45   ` Marc-André Lureau
2020-12-16 16:50   ` Alex Bennée
2020-12-15 22:41 ` Eduardo Habkost [this message]
2020-12-16  7:53   ` [PATCH 2/2] qom: Assert that objects being destroyed have no parent Marc-André Lureau
2020-12-16  9:55     ` Daniel P. Berrangé
2020-12-16 13:31     ` Paolo Bonzini
2020-12-16 16:15       ` Alex Bennée
2020-12-16 16:52   ` Alex Bennée

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