MTP: Fix race between on_uevent and do_unmount.

I've never seen this happen personally, but an Ubuntu bug reported
that on_uevent fired after the gudev client had been finalized, so
it must be possible to race between an explicit unmount and
physically unplugging a device. I made a brief attempt to reproduce
this but couldn't.

In any case, it's easy enough to protect against by taking a few
measures:

1) Explicitly disconnect the signal handler before unref'ing the
   gudev client.
2) Use g_signal_connect_object to keep the backend alive enough
   for on_uevent to complete.
3) NULL out the dev_path so that if we end up in on_uevent after
   do_unmount has cleared the dev_path, the compare will fail
   gracefully.

1 files changed, 1 insertions, 0 deletions

diff --git a/daemon/gvfsbackendmtp.h b/daemon/gvfsbackendmtp.h
index 9dbaa0c4..4137b65b 100644
--- a/daemon/gvfsbackendmtp.h
+++ b/daemon/gvfsbackendmtp.h
@@ -47,6 +47,7 @@ struct _GVfsBackendMtp
 
 #ifdef HAVE_GUDEV
   GUdevClient *gudev_client;
+  gulong on_uevent_id;
 #endif
 
   GMutex mutex;