Re: kern/38670: ^Z does not work anymore for this program.

[christos%zoulas.com@localhost (Christos Zoulas)]

On Feb 22, 10:01am, dholland-bugs%netbsd.org@localhost (David Holland) wrote:
-- Subject: Re: kern/38670: ^Z does not work anymore for this program.

| Changing that call to cv_wait_sig() ought to restore the previous
| behavior; however, it's not clear that this is a particularly good
| idea, because if a signal arrives and results in ERESTARTSYS there'll
| be another child process created, and if it results in EINTR then the
| parent and the child will both be running on the same stack in the
| same address space, and demons will fly out of someone's nose.
| 
| However, since having arbitrarily long uninterruptible waits isn't
| such a great idea, maybe we should try to come up with a way to make
| this work. Or maybe an adequate substitute is to change the WCHAN to
| "vfork" so one can at least tell what's happening and find/kill off
| the child process if things are stuck. But this probably would
| probably require breaking the CV abstraction.
| 
| Also, I wonder what happens if someone does ptrace(PT_ATTACH, ...) on
| a vfork child. This should probably be forbidden; it currently isn't
| and I suspect it will make a mess.

Thanks for the explanation. I guess we should leave this open until we
fix at least the ptrace case.

christos