kernel: nil check, exited procs handling in postnote()

make sure not to dereference Proc* nil pointer. this can potentially
happen from devip which has code like:

	if(er->read4p)
		postnote(er->read4p, 1, "unbind", 0);

the process it is about to kill can zero er->read4p at any time,
so there is the possibility of the condition to be true and then
er->read4p becoming nil.

check if the process has already exited (p->pid == 0) in postnote()
under p->debug qlock.

0 files changed, 0 insertions, 0 deletions