diff options
Diffstat (limited to 'src/corelib/kernel/qobject_p.h')
| -rw-r--r-- | src/corelib/kernel/qobject_p.h | 28 |
1 files changed, 22 insertions, 6 deletions
diff --git a/src/corelib/kernel/qobject_p.h b/src/corelib/kernel/qobject_p.h index 66c19d174e..0b827a52ca 100644 --- a/src/corelib/kernel/qobject_p.h +++ b/src/corelib/kernel/qobject_p.h @@ -268,7 +268,10 @@ public: ~ConnectionData() { - deleteOrphaned(orphaned.loadRelaxed()); + Q_ASSERT(ref.loadRelaxed() == 0); + auto *c = orphaned.fetchAndStoreRelaxed(nullptr); + if (c) + deleteOrphaned(c); SignalVector *v = signalVector.loadRelaxed(); if (v) free(v); @@ -277,12 +280,19 @@ public: // must be called on the senders connection data // assumes the senders and receivers lock are held void removeConnection(Connection *c); - void cleanOrphanedConnections(QObject *sender) + enum LockPolicy { + NeedToLock, + // Beware that we need to temporarily release the lock + // and thus calling code must carefully consider whether + // invariants still hold. + AlreadyLockedAndTemporarilyReleasingLock + }; + void cleanOrphanedConnections(QObject *sender, LockPolicy lockPolicy = NeedToLock) { if (orphaned.loadRelaxed() && ref.loadAcquire() == 1) - cleanOrphanedConnectionsImpl(sender); + cleanOrphanedConnectionsImpl(sender, lockPolicy); } - void cleanOrphanedConnectionsImpl(QObject *sender); + void cleanOrphanedConnectionsImpl(QObject *sender, LockPolicy lockPolicy); ConnectionList &connectionsForSignal(int signal) { @@ -307,8 +317,14 @@ public: signalVector.storeRelaxed(newVector); if (vector) { - vector->nextInOrphanList = orphaned.loadRelaxed(); - orphaned.storeRelaxed(ConnectionOrSignalVector::fromSignalVector(vector)); + Connection *o = nullptr; + /* No ABA issue here: When adding a node, we only care about the list head, it doesn't + * matter if the tail changes. + */ + do { + o = orphaned.loadRelaxed(); + vector->nextInOrphanList = o; + } while (!orphaned.testAndSetRelease(o, ConnectionOrSignalVector::fromSignalVector(vector))); } } int signalVectorCount() const { |