[lkml]   [2015]   [Mar]   [16]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [PATCH v2 0/7] CLONE_FD: Task exit notification via file descriptor
On Monday 16 March 2015 14:44:20 Kees Cook wrote:
> > Set the close-on-exec flag on the new file
> >descriptor. See the description of the O_CLOEXEC flag in open(2) for
> >reasons why this may be useful.
> This begs the question: what happens when all CLONE_FD fds for a
> process are closed? Will the parent get SIGCHLD instead, will it
> auto-reap, or will it be un-wait-able (I assume not this...)

Depends on CLONE_AUTOREAP. If it's on, then no one gets SIGCHLD, no one can
wait() on it and the process autoreaps itself.

If it's no active, then the old rules apply: parent gets SIGCHILD and can
wait(). If the parent exited first, then the child gets reparented to init,
which can do the wait().

A child without CLONE_AUTOREAP should be wait()able. If it gets wait()ed
before the clonefd is read, the clonefd() will return a 0 read. If it gets
read before wait, then wait() reaps another child or returns -ECHILD. That's
no different than two threads doing simultaneous wait() on the same child.
Thiago Macieira - thiago.macieira (AT)
Software Architect - Intel Open Source Technology Center

 \ /
  Last update: 2015-03-16 23:21    [W:0.101 / U:3.928 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site