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Date: Mon, 13 Jun 2005 19:45:51 +0100
From: Christoph Hellwig <hch@infradead.org>
To: Scott Long <scottl@samsco.org>
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Cc: Daniel Eischen <deischen@freebsd.org>,
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Subject: Re: contigmalloc() and mmap()
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On Mon, Jun 13, 2005 at 12:37:07PM -0600, Scott Long wrote:
> How does linux handle the implications of fork(2) in this scenario?

it's still counted as the same instance.  Similar for dup or passing
descriptors over AF_UNIX sockets. The data is explictly not per-process
but per instance.

There's not a lot of users actually using this feature, only the tty
subsystem and multi-channel sound drivers for the old oss API that
allowed multiple opens of /dev/dsp that way come to mind.

Lot's of driver use file->private to get at per-device data easily,
but that's just a shortcut.