Subject: Re: RFC: A revised timerfd API
From: Thomas Gleixner <tglx@linutronix.de>
To: Michael Kerrisk <mtk-manpages@gmx.net>
Cc: david@hardeman.nu, davidel@xmailserver.org, drepper@redhat.com,
       geoff@gclare.org.uk, linux-kernel@vger.kernel.org,
       akpm@linux-foundation.org, hch@lst.de, corbet@lwn.net,
       rdunlap@xenotime.net, vda.linux@googlemail.com,
       torvalds@linux-foundation.org, Lee.Schermerhorn@hp.com
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Date: Tue, 18 Sep 2007 13:30:11 +0200
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On Tue, 2007-09-18 at 13:08 +0200, Michael Kerrisk wrote:
> > > it does make the API a little more clumsy.
> > 
> > Hmm, we might do something like:
> > 
> > 	timer_gettime(fd | POSIX_TIMER_FD, .....);
> > 
> > So the kernel looks up the fd in order to figure out the timer_id, which
> > needs to be referenced in filep->private_data anyway.
> 
> And you'd need similar for timer_settime() and, perhaps,
> timer_getoverrun().  But it seems slightly ugly, in the same way that
> my idea in option (d) of returning a file descriptor from
> timer_create() seems a slightly ugly.  (And can we guarantee that
> the [timerid] space is distinct from the [fd|POSIX_TIMER_FD] space?)

If we use the most significant bit for POSIX_TIMER_FD, we should be
fine.

	tglx


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