CVS commit: src/sys/kern

["Paul Goyette" <pgoyette%netbsd.org@localhost>]

Module Name:    src
Committed By:   pgoyette
Date:           Tue Oct 13 00:29:35 UTC 2015

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

Log Message:
In spawn_return() we temporarily move the process state to SSTOP, but
without updating its p_waited value or its parent's p_nstopchild
counter.  Later, we restore the original state, again without any
adjustment of the related values.  This leaves a relatively short
window when the values are inconsistent and could interfere with the
proper operation of sys_wait() for the parent (if it manages to be
scheduled;  it's not totally clear what, if anything, prevents
scheduling/execution of the parent).

If during this window, any of the checks being made result in an
error, we call exit1() which will eventually migrate the process's
state to SDEAD (with an intermediate transition to SDYING).  At
this point the other variables get updated, and we finally restore
a consistent state.

This change updates the p_waited and parent's p_nstopchild at each
step to eliminate any windows during which the values could lead to
incorrect decisions.

Fixes PR kern/50330

Pullups will be requested for NetBSD-7, -6, -6-0, and -6-1


To generate a diff of this commit:
cvs rdiff -u -r1.419 -r1.420 src/sys/kern/kern_exec.c

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