LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Denis Vlasenko <vda.linux@googlemail.com>
To: Philippe Troin <phil@fifi.org>
Cc: linux-kernel@vger.kernel.org
Subject: Re: O_NONBLOCK setting "leak" outside of a process??
Date: Fri, 2 Feb 2007 00:00:40 +0100	[thread overview]
Message-ID: <200702020000.40524.vda.linux@googlemail.com> (raw)
In-Reply-To: <87bqkhuqpp.fsf@tantale.fifi.org>

On Tuesday 30 January 2007 04:40, Philippe Troin wrote:
> > int main() {
> >         fcntl(0, F_SETFL, fcntl(0, F_GETFL, 0) | O_NONBLOCK);
> >         return 0;
> > }
> > 
> > int main() {
> >         fcntl(0, F_SETFL, fcntl(0, F_GETFL, 0) & ~O_NONBLOCK);
> >         return 0;
> > }
> > 
> > If I run "nonblock" in Midnight Commander in KDE's Konsole,
> > screen redraw starts to work ~5 times slower. For example,
> > Ctrl-O ("show/hide panels" in MC) takes ~0.5 sec to redraw.
> > This persists after the program exits (which it
> > does immediately as you see).
> > Running "block" reverts things to normal.
> > 
> > I mean: how can O_NONBLOCK _issued in a process which
> > already exited_ have any effect whatsoever on MC or Konsole?
> > They can't even know that it did it, right?
> > 
> > Either I do not know something subtle about Unix or some sort
> > of bug is at work.
> 
> Because they all share the same stdin file descriptor, therefore they
> share the same file descriptor flags?

What share the same file descriptor? MC and programs started from it?

I thought after exec() fds atre either closed (if CLOEXEC) or
becoming independent from parent process
(i.e. it you seek, close, etc your fd, parent would not notice that).

Am I wrong?
--
vda

  reply	other threads:[~2007-02-01 23:03 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-01-27 20:52 Denis Vlasenko
2007-01-30  3:40 ` Philippe Troin
2007-02-01 23:00   ` Denis Vlasenko [this message]
2007-02-01 23:15     ` Philippe Troin
2007-02-02 12:10       ` Roland Kuhn
2007-02-02 13:48         ` Guillaume Chazarain
2007-02-02 15:04           ` Roland Kuhn
2007-02-02 18:59             ` Philippe Troin
2007-02-05 10:49               ` bert hubert
2007-02-04  0:55         ` David Schwartz
2007-02-04  1:22           ` Denis Vlasenko
2007-02-04  7:56             ` David Schwartz
2007-02-04 20:11               ` Michael Tokarev
2007-02-04 21:08                 ` David Schwartz

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=200702020000.40524.vda.linux@googlemail.com \
    --to=vda.linux@googlemail.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=phil@fifi.org \
    --subject='Re: O_NONBLOCK setting "leak" outside of a process??' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).