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From: Hans Petter Selasky <hselasky@c2i.net>
To: freebsd-hackers@freebsd.org
Date: Mon, 10 Aug 2009 15:27:31 +0200
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Cc: Krassimir Slavchev <krassi@bulinfo.net>
Subject: Re: Help with device drivers
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On Monday 10 August 2009 13:39:31 Krassimir Slavchev wrote:
> If I try to open the device from userland with:
> fd = open("/dev/xxx0", O_RDWR) it fails because open() tries to open the
> device for reading first and then for writing.

There is a bug in the code. If you open using read+write flags, then the FIFO 
open routine is called two times. The RD+WR check should be moved to the ioctl 
routine.

http://perforce.freebsd.org/chv.cgi?CH=167171

--HPS