devfs_get/set_cdevpriv functions from FreeBSD

[Markus Pfeiffer]

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Dear all,
(I think in particular Matt and Alex H.)

while porting drivers from FreeBSD some of us have stumbled over the functi=
ons
devfs_get_cdevpriv and devfs_set_cdevpriv, which store some
per-open-filedescriptor information for some devices.

I looked into the FreeBSD code and the implementation seems weird to me sin=
ce
they store the filedescriptor on syscall in their thread struct and the fun=
ctions
rely on that hidden state.

Question is now: Should we have similar functionality (i.e. per open
filedescriptor "private" data) and if yes how to best implement that. I know
that AlexH had made some suggestion but I cannot find it in the IRC logs and
it would probably be more efficient doing this by mail.=20

Markus
--=20
Markus Pfeiffer, University of St Andrews
email: markus.pfeiffer at morphism.de | xmpp: markus.pfeiffer at jabber.morphism.=
de

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