Re: epoll and shared fd's

[Davide Libenzi <davidel@xmailserver.org>]

On Tue, 26 Feb 2008, Michael Kerrisk wrote:

> Okay -- I'll look at it some more.  I am however loathe to drop the
> term open file description, because POSIX uses, as well as a number of
> other Linux man pages by now.

Heh, POSIX. Now doesn't take a genius to see that "file description" and 
"file descriptor" looks amazingly similar, does it? :)


> > That'd mean placing an eventpoll custom hook into sys_close(). Looks 
> > very bad to me, and probably will look even worse to other kernel 
> > folks. Is not much a performance issue (a check to see if a file* is 
> > an eventpoll file is as easy as comparing the f_op pointer), but a 
> > design/style issue.
>
> Oh -- I wasn't suggesting we could make the change now -- it would
> break the ABI and all that.  I was just wondering why the decision
> wasn't made to do it the other way to begin with.  The existing
> semantics are somewhat couterintuitive, and potentially interact
> libraries that do private manipulations with file descriptors.

For the same reason that a custom hook in sys_close wouldn't have passed 
the radar ;)
As far as problems with libraries doing tricks with fds, that's an issue 
that goes beyond epoll.



- Davide