Giant might have been temporarily dropped while waiting for proctree_lock, allowing for an intervening tty_close() that cleared tp->t_session.
Giant might have been temporarily dropped while waiting for proctree_lock, allowing for an
intervening tty_close() that cleared tp->t_session.

Submitted by:	tegge
MFC:		1 day

jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase