rpc_transport entries(xprt) are added to the conf->xprt_list during client connection with the server. But the client object is created and assigned to that transport object only during GF_HANDSK_SETVOLUME. Hence till that period, there could be xprt entries in the xprt_list without client associated with it. Added a check to validate the client object during upcall notify. Change-Id: I11e2fcd8b0a67e35302ede478b777b72d1973456 BUG: 1235542 Signed-off-by: Soumya Koduri <skoduri@redhat.com> Reviewed-on: http://review.gluster.org/11411 Reviewed-by: Krishnan Parthasarathi <kparthas@redhat.com> Tested-by: NetBSD Build System <jenkins@build.gluster.org> Reviewed-by: Kaleb KEITHLEY <kkeithle@redhat.com>