d1e340364b
be done internally. Ensure that no one can fsetown() to a dying process/pgrp. We need to check the process for P_WEXIT to see if it's exiting. Process groups are already safe because there is no such thing as a pgrp zombie, therefore the proctree lock completely protects the pgrp from having sigio structures associated with it after it runs funsetownlst. Add sigio lock to witness list under proctree and allproc, but over proc and pgrp. Seigo Tanimura helped with this.