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SubjectRe: >256 ptys (previous subject line was garbage)
Date
In article <linux.kernel.199806090036.KAA08187@vindaloo.atnf.csiro.au>,
Richard Gooch <Richard.Gooch@atnf.CSIRO.AU> wrote:
>tytso@mit.edu writes:
>> Date: Fri, 5 Jun 1998 12:59:59 +0200 (MET DST)
>> From: Peter Svensson <petersv@df.lth.se>
>>
>> I am not familiar with the reasons for using major/minor-pair for
>> locking so I don't know if another solution is feasable. Do you have
>> any pointers for additional reading? :-)
>>
>> The problem is things like /dev/modem being a symlink (or perhaps even a
>> hard link) to /dev/ttyS0. So it would be useful to use a lockfile that
>> includes the major and minor device number, in addition to using a
>> lockfile that is based on the device name. The basic idea is that
>> people want to have different device names to refer to the same device,
>> so we need to lock based the major/minor devices.
>
>Well, I've seen one comment already questioning whether major/minor
>device locks are the better way of doing it, instead of flock(2).
>However, ignoring that, I think it would be simple enough to implement
>a non tty-specific locking scheme in devfs. I already have the auto
>ownership facility.
>What does this device locking need? Just limit the number of open(2)s
>to 1?

More than that.

You need a locking scheme that will support a getty listening on the
port (one open) and will also support things that want to grab the
port for outgoing traffic (the second open.)

____
david parsons \bi/ I [heart] mgetty
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