Date: Mon, 24 Jul 1995 10:23:39 +1000 From: Bruce Evans <bde@zeta.org.au> To: ache@astral.msk.su, terry@cs.weber.edu Cc: bde@zeta.org.au, hackers@freebsd.org, harry@hgac.com, jkh@violet.berkeley.edu Subject: Re: dial up at > 9600 baud Message-ID: <199507240023.KAA27013@godzilla.zeta.org.au>
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>It's also broken because the wait for DCD on the blocking open is >only in effect when the open count is 0. After one open as a >non-blocking open, the reference count is one, and subsequent opens >are not *supposed* to block. I disagree. POSIX requires it to block. Not blocking would cause stupid behaviour such as `stty -f /dev/ttyd0' unblocking any getty sleeping in open for /dev/ttyd0. Once the open has completed it is hard to recover. 1.1.5 fiddles with the open count to make blocking work. There can be any number of processes sleeping in open() and any number of processes with it open (having opened it in nonblocking mode). 2.x doesn't fiddle with the open count yet, so blocking doesn't work right if there is one or more nonblocking opens such as the `stty -f' mentioned above. Bruce
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