CVS commit: src/sys/kern

["Robert Elz" <kre%netbsd.org@localhost>]

Module Name:    src
Committed By:   kre
Date:           Wed Nov  9 00:30:17 UTC 2016

Modified Files:
        src/sys/kern: kern_exit.c

Log Message:
PR kern/51600 ; PR standards/51606

Revert 1.264 - that was intended to fix 51600, but didn't, it just
hid the problem, and caused 51606.  This fixes 51606.

Handle waiting on a process that has been detatched from its parent
because of being ptrace'd by some other process.  This fixes 51600.
("handle" here means that the wait() hangs, or with WNOHANG, returns 0,
we cannot actually wait on a process that is not currently an attached
child.)

Note: the detatched process waiting is not yet perfect (it fails to
take account of options like WALLSIG and WALTSIG) - suport for those
(that is, ignoring a detatched child that one of those options will
later cause to be ignored when the process is re-attached.)

For now, for ither than when waiting for a specific process ID, when
a process does a wait() sys call (any of them), has no applicable
children attached that can be returned, and has at least one detatched
child, then we do a linear search of all processes to look for a
suitable detatched child.  This is likely to be slow - but very rare.
Eventually it might be better to keep a list of detatched children
per process.


To generate a diff of this commit:
cvs rdiff -u -r1.264 -r1.265 src/sys/kern/kern_exit.c

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.