broadband-modem: cancellable may not be given during disable()

If the modem is currently being disposed, we may not get a proper GCancellable
when disabling, so try to handle that case in order to avoid warnings like:

    GLib-GObject-CRITICAL **: g_object_ref: assertion `G_IS_OBJECT (object)' failed

    #0  0x00007ffff7ab1ba0 in g_log () from /usr/lib64/libglib-2.0.so.0
    #1  0x00007ffff7b99784 in g_object_ref () from /usr/lib64/libgobject-2.0.so.0
    #2  0x0000000000456c05 in disable (self=0x50d3f0, cancellable=0x0,
    callback=<value optimized out>, user_data=<value optimized out>) at
    mm-broadband-modem.c:7052
    #3  0x0000000000431e69 in handle_enable_auth_ready (self=0x50d3f0,
    res=<value optimized out>, ctx=0xa41200) at mm-iface-modem.c:1216
    #4  0x00007ffff7e7f447 in g_simple_async_result_complete () from
    /usr/lib64/libgio-2.0.so.0
    #5  0x0000000000427bc1 in authorize_ready (authp=<value optimized
    out>, res=<value optimized out>, simple=0x51d810) at
    mm-base-modem.c:1015
    #6  0x00007ffff7e7f447 in g_simple_async_result_complete () from
    /usr/lib64/libgio-2.0.so.0
    #7  0x00007ffff7e7f549 in ?? () from /usr/lib64/libgio-2.0.so.0
    #8  0x00007ffff7aaa5c3 in g_main_context_dispatch () from
    /usr/lib64/libglib-2.0.so.0
    #9  0x00007ffff7aaa940 in ?? () from /usr/lib64/libglib-2.0.so.0
    #10 0x00007ffff7aaad7a in g_main_loop_run () from /usr/lib64/libglib-2.0.so.0
    #11 0x0000000000417ef2 in main (argc=<value optimized out>,
    argv=<value optimized out>) at main.c:150

    GLib-GObject-CRITICAL **: g_object_unref: assertion `G_IS_OBJECT
    (object)' failed

    #0  0x00007ffff7ab1ba0 in g_log () from /usr/lib64/libglib-2.0.so.0
    #1  0x000000000044af26 in disabling_context_complete_and_free
    (ctx=0xa408a0) at mm-broadband-modem.c:6788
    #2  0x0000000000431e69 in handle_enable_auth_ready (self=0x50d3f0,
    res=<value optimized out>, ctx=0xa41200) at mm-iface-modem.c:1216
    #3  0x00007ffff7e7f447 in g_simple_async_result_complete () from
    /usr/lib64/libgio-2.0.so.0
    #4  0x0000000000427bc1 in authorize_ready (authp=<value optimized
    out>, res=<value optimized out>, simple=0x51d810) at
    mm-base-modem.c:1015
    #5  0x00007ffff7e7f447 in g_simple_async_result_complete () from
    /usr/lib64/libgio-2.0.so.0
    #6  0x00007ffff7e7f549 in ?? () from /usr/lib64/libgio-2.0.so.0
    #7  0x00007ffff7aaa5c3 in g_main_context_dispatch () from
    /usr/lib64/libglib-2.0.so.0
    #8  0x00007ffff7aaa940 in ?? () from /usr/lib64/libglib-2.0.so.0
    #9  0x00007ffff7aaad7a in g_main_loop_run () from /usr/lib64/libglib-2.0.so.0
    #10 0x0000000000417ef2 in main (argc=<value optimized out>,
    argv=<value optimized out>) at main.c:150

Reported by: Ben Chan <benchan@chromium.org>

Partially fixes: https://bugzilla.gnome.org/show_bug.cgi?id=684693

1 files changed, 5 insertions, 7 deletions

diff --git a/src/mm-broadband-modem.c b/src/mm-broadband-modem.c
index c3f02c0b..7423130a 100644
--- a/src/mm-broadband-modem.c
+++ b/src/mm-broadband-modem.c
@@ -6813,7 +6813,8 @@ disabling_context_complete_and_free (DisablingContext *ctx)
     }
 
     g_object_unref (ctx->result);
-    g_object_unref (ctx->cancellable);
+    if (ctx->cancellable)
+        g_object_unref (ctx->cancellable);
     g_object_unref (ctx->self);
     g_free (ctx);
 }
@@ -6837,10 +6838,7 @@ disable_finish (MMBaseModem *self,
                GAsyncResult *res,
                GError **error)
 {
-    if (g_simple_async_result_propagate_error (G_SIMPLE_ASYNC_RESULT (res), error))
-        return FALSE;
-
-    return TRUE;
+    return !g_simple_async_result_propagate_error (G_SIMPLE_ASYNC_RESULT (res), error);
 }
 
 #undef INTERFACE_DISABLE_READY_FN
@@ -7079,12 +7077,12 @@ disable (MMBaseModem *self,
         ctx = g_new0 (DisablingContext, 1);
         ctx->self = g_object_ref (self);
         ctx->result = result;
-        ctx->cancellable = g_object_ref (cancellable);
+        ctx->cancellable = (cancellable ? g_object_ref (cancellable) : NULL);
         ctx->step = DISABLING_STEP_FIRST;
 
         disabling_step (ctx);
         return;
-    }
+      }
     }
 
     g_simple_async_result_complete_in_idle (result);