Re: Synchronous signal delivery..

From: Abramo Bagnara (
Date: Fri Feb 14 2003 - 08:57:38 EST

Alan Cox wrote:
> On Fri, 2003-02-14 at 08:55, Abramo Bagnara wrote:
> > This reminds me the unfortunate (and much needed) lack of an unified way
> > to send/receive out-of-band data to/from a regular fd.
> >
> > Something like:
> > oob = fd_open(fd, channel, flags);
> > write(oob, ...)
> > read(oob, ....)
> > close(oob);
> >
> > Don't you think it's time to introduce it and to start to avoid the
> > proliferation of different tricky ways to do the same things?
> Why are you trying to throw yet more crap into the kernel. Linus signals
> as fd thing is questionable but makes a little sense (its in many ways
> more unix than the traditional approach of using real time queued
> signal since you can now select on it)

My comment was not related to "signals as fd" stuff, but to the more
generic need (implicit in Linus reply to Davide's comment) to have
sometimes a control channel for an open fd (much like a file approach to
ioctl/fcntl problem space).

FWIW and IIRC a similar solution (based on a fs approach) was suggested
also by Al Viro some time ago.

> Out of band data is a second data channel, so open two pipes. Jeez

What about the relation between the two channels?

Abramo Bagnara             

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