Date: Tue, 10 Sep 2002 09:30:03 -0700 (PDT) From: alo@louko.com (Antti Louko) To: freebsd-bugs@FreeBSD.org Subject: Re: misc/41331: Pthread library open sets O_NONBLOCK flag and causes unnecessary EAGAIN errors especially with /dev/stdout. Message-ID: <200209101630.g8AGU36d091105@freefall.freebsd.org>
next in thread | raw e-mail | index | archive | help
The following reply was made to PR misc/41331; it has been noted by GNATS.
From: alo@louko.com (Antti Louko)
To: archie@packetdesign.com
Cc: freebsd-gnats-submit@FreeBSD.org, deischen@freebsd.org
Subject: Re: misc/41331: Pthread library open sets O_NONBLOCK flag and causes
unnecessary EAGAIN errors especially with /dev/stdout.
Date: 10 Sep 2002 16:26:31 -0000
Sender: archie@dellroad.org
Date: Tue, 10 Sep 2002 08:26:40 -0700
From: Archie Cobbs <archie@packetdesign.com>
Organization: Packet Design
X-Accept-Language: en
CC: freebsd-gnats-submit@FreeBSD.org, deischen@freebsd.org
Antti Louko wrote:
> I just tried it in 4.6 Release and 4.6.2 and it still occurs.
I think this is a kernel bug, rather than a pthread bug.
What's happening is that the file descriptor associated with
/dev/stdout is "inheriting" the flags associated with file
descriptor 0. This happens on both -stable and -current.
This seems like broken behavior to me: flags should be associated
with the file descriptor, not the underlying device or entity.
But I don't know what the "official" semantics of /dev/stdout
are supposed to be.
The program below demonstrates the problem:
$ cc -g -Wall -o flags flags.c
$ ./flags
O_NONBLOCK is set
But the O_NONBLOCK is not set in the kernel. It is probably set in
/usr/src/lib/libc_r/uthread/uthread_fd.c (which sets O_NONBLOCK flags
for fds in range 0..2) or somewhere else in libc_r because it doesn't
happen without thread library. But someone who is familiar with the
pthreads library should check what should happen.
I don't feel competent to fix this.
Regards,
Antti
To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe freebsd-bugs" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?200209101630.g8AGU36d091105>