Document that disconnectNotify may be called with a mutex locked

And that connectNotify and disconnectNotify might be called from
another thread

Task-number: QTBUG-34829

Change-Id: Id118b97b92e9aa085a1d4368282294f90cfb1706
Reviewed-by: Alan Alpert <aalpert@blackberry.com>

1 files changed, 13 insertions, 0 deletions

diff --git a/src/corelib/kernel/qobject.cpp b/src/corelib/kernel/qobject.cpp
index f8664ba3a2..3fbeaa8712 100644
--- a/src/corelib/kernel/qobject.cpp
+++ b/src/corelib/kernel/qobject.cpp
@@ -2996,6 +2996,10 @@ bool QObject::disconnect(const QObject *sender, const QMetaMethod &signal,
     expensive initialization only if something is connected to a
     signal.
 
+    \warning This function is called from the thread which performs the
+    connection, which may be a different thread from the thread in
+    which this object lives.
+
     \sa connect(), disconnectNotify()
 */
 
@@ -3022,6 +3026,15 @@ void QObject::connectNotify(const QMetaMethod &signal)
     modularity. However, it might be useful for optimizing access to
     expensive resources.
 
+    \warning This function is called from the thread which performs the
+    disconnection, which may be a different thread from the thread in
+    which this object lives. This function may also be called with a QObject
+    internal mutex locked. It is therefore not allowed to re-enter any
+    of any QObject functions from your reimplementation and if you lock
+    a mutex in your reimplementation, make sure that you don't call QObject
+    functions with that mutex held in other places or it will result in
+    a deadlock.
+
     \sa disconnect(), connectNotify()
 */