Re: [RFC PATCH] waitfd: file descriptor to wait on child processes

Alan Cox
2008-12-09T19:05:13Z

> > This propogates the fundamental braindamage of waitpid - the fact the
> > notification only works on child process trees.
> >
> > Here is a more elegant suggestion - use epoll, inotify and friends fully
> > on /proc process nodes.

> Last I checked inotify was not supported in /proc, or at least most of
> it. What kind of work load is it to change that?

I don't know but I think it would be the better approach to find it. That
also separates notification of state to parents from the general problem
of wanting to know when a service has died, which seems to be an ever
more common point of interest on the desktop in particular.

File content change notification for /proc is hard because the contents
don't exist in the normal way and get updated but can be done if there is
a wait queue for the job. Actual changes to structure (new directories
etc) is in part a similar problem but there are clear points already in
existence when the proc nodes are created/destroyed and thus notification
can occur.