Re: In-kernel process exit hooks?

[Taylor R Campbell <campbell+netbsd-tech-kern%mumble.net@localhost>]

   Date: Fri, 8 Jan 2016 09:00:03 +0800 (PHT)
   From: Paul Goyette <paul%whooppee.com@localhost>

   On Fri, 8 Jan 2016, Paul Goyette wrote:

   > The saga continues!   :)
   >
   > <snip>
   >
   > Next, I'm going to have a look at fd_getfile2()/fclose() and see if that
   > is a viable approach.

   Hmmm.  The comments in kern/kern_descrip.c for fd_getfile2() require 
   that the process is not allowed to fork or exit "across this call" 
   (which I assume means "until the reference to the struct file is 
   released").

I don't think that's what it means.  I think it means the process
whose descriptor we're asking for can't fork or exit *during the call*
to fd_getfile2.  In this case, it's the current process, so that's not
an issue.

The reason it is an issue stated in a comment is that the routine
appears to have been written for the purpose of procfs, in which case
the calling process is often not the same as the process passed to
fd_getfile2.