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	Sat, 22 Aug 1998 14:20:51 +1000
Date: Sat, 22 Aug 1998 14:20:51 +1000
From: Bruce Evans <bde@zeta.org.au>
Message-Id: <199808220420.OAA07007@godzilla.zeta.org.au>
To: bde@zeta.org.au, freebsd-bugs@FreeBSD.ORG, yasu@codec.mrit.mei.co.jp
Subject: Re: kern/7658: (1) rlogin from some host to the FreeBSD host with very slow link. (ping reports around 200ms - 500ms delay)
Cc: FreeBSD-gnats-submit@FreeBSD.ORG
Sender: owner-freebsd-bugs@FreeBSD.ORG
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>The following procedure still cause to hung terminal:
>  >  (1) rlogin from some host to the FreeBSD host with very slow link.
>  >      (ping reports around 200ms - 500ms delay)
>  >  (2') type ^C several times. (At this point the terminal stops to accept
>  >      any keys.)
>
>I did not mentioned but I rlogined 3 times.
>      rlogin            rlogin              rlogin
>Host A ----> Host B -----------------> Host C -----> Host D
>FreeBSD      SunOS      slow link     Solaris       FreeBSD
>
>After I rlogined from Host A to Host D, if I type ^C several times,
>then terminal seems to become frozen.

I created a slow link using kernel pppd at 1200 bps, and couldn't see
any problem for:

      rlogin            rlogin              rlogin
Host A ----> Host B -----------------> Host A -----> Host B
FreeBSD      FreeBSD    slow link     FreeBSD       FreeBSD

The panic may have been caused by the following events:

hangup -> revoked pty -> pty's vnodes lose their mount point ->
kernel bug for fsync on vnodes with no mount point.

FreeBSD returns -1/EIO for reading from revoked ptys instead of the
more normal 0/no error.  Some broken applications spin reading -1/EIO.
This may look like a hang.

Bruce

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