Re: something funny about tty's on 2.6.4-rc1-mm1

From: H. Peter Anvin
Date: Tue Mar 02 2004 - 00:49:04 EST


Followup to: <20040301184512.GA21285@xxxxxxxxxxxxxxxxx>
By author: Nuno Monteiro <nuno@xxxxxxxxxx>
In newsgroup: linux.dev.kernel
>
> I know for a fact that I don't have 157 logged in users (well, there's
> only 45 processes running right now), and shouldn't pts' be recycled, and
> a lower number be assigned? The last kernel I ran was 2.6.3, and none of
> this happened.
>
> My config is:
>
> CONFIG_UNIX98_PTYS=y
> CONFIG_LEGACY_PTYS=y
> CONFIG_LEGACY_PTY_COUNT=512
>
> and this is a plain jane static /dev -- not devfs nor udev. Despite the
> supposedly 157 users logged in, /dev/pts only contains '358', which is
> the one allocated to this instance of aterm right now.
>
> nuno@hobbes:~$ ls -l /dev/pts
> total 0
> crw--w---- 1 nuno users 136, 102 Mar 1 18:41 358
>
> In the mean time I'll fall back to 2.6.3.
>

No need to, as there is no error (except that you need a newer libc or
ls to properly show the device number.)

As RBJ said, ptys are now recycled in pid-like fashion, which means
numbers won't be reused until wraparound happens. This is good for
security/fault tolerance, at least to some minor degree.

-hpa

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