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On Mon, Sep 04, 2006 at 11:26:57AM +0200, Quentin Garnier wrote:
> On Mon, Sep 04, 2006 at 11:20:45AM +0159, Jiri Slaby wrote:
> > Hello,
> >=20
> > I have netbsd cdev driver. I do multiple opens (more instances) on it, =
is=20
> > there any way to get know about each close of these instances?
> >=20
> > 'A' process does:
> > open
> > ioctl(START_IT) + others
> > for (;;) {
> > poll
> > ioctl(LOCK_IT)
> > read it by mmap
> > ioctl(UNLOCK_IT)
> > }
> >=20
> > ^C, so kernel calls close for it and releases A process' resources.
> >=20
> > If there is also process B, which does the very same thing, for first=
=20
> > process killed there is no close call and kernel turns into ddb. I do n=
eed=20
> > to know about all closes -- is there such a way?
>=20
> Yes, make the device clonable, like e.g. tap(4) and bpf(4).

So, actually, that won't give you mmap.  Support for it should be added.
The cdev has to keep track of the resources and free them all at close
time...  This is probably not ideal, but support for mmap on fdclone'd
descriptors really should be added.

--=20
Quentin Garnier - cube@cubidou.net - cube@NetBSD.org
"When I find the controls, I'll go where I like, I'll know where I want
to be, but maybe for now I'll stay right here on a silent sea."
KT Tunstall, Silent Sea, Eye to the Telescope, 2004.

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