From: daw@mozart.cs.berkeley.edu (David Wagner)
To: linux-kernel@vger.kernel.org
Subject: Re: light weight user level semaphores
Date: 24 Apr 2001 00:19:46 GMT [thread overview]
Message-ID: <9c2gr2$u7s$1@abraham.cs.berkeley.edu> (raw)
In-Reply-To: <E14qHRp-0007Yc-00@the-village.bc.nu> <Pine.LNX.4.31.0104190944090.4074-100000@penguin.transmeta.com>
Linus Torvalds wrote:
>Ehh.. I will bet you $10 USD that if libc allocates the next file
>descriptor on the first "malloc()" in user space (in order to use the
>semaphores for mm protection), programs _will_ break.
>
>You want to take the bet?
Good point. Speaking of which:
ioctl(fd, UIOCATTACHSEMA, ...);
seems to act like dup(fd) if fd was opened on "/dev/usemaclone"
(see drivers/sgi/char/usema.c). According to usema(7), this is
intended to help libraries implement semaphores.
Is this a bad coding? Should the kernel really support an ioctl()
that can silently allocate the next file descriptor? This seems
like asking for trouble. Or, maybe I just misunderstood something.
next prev parent reply other threads:[~2001-04-24 0:21 UTC|newest]
Thread overview: 62+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20010417114433.D1108@w-mikek2.sequent.com>
2001-04-17 19:48 ` light weight user level semaphores Linus Torvalds
2001-04-18 18:13 ` Bernd Eckenfels
2001-04-18 19:35 ` Ulrich Drepper
2001-04-19 8:20 ` Alon Ziv
2001-04-19 8:52 ` Abramo Bagnara
2001-04-19 9:08 ` Alexander Viro
2001-04-19 10:44 ` Abramo Bagnara
2001-04-19 16:11 ` Linus Torvalds
2001-04-19 16:33 ` Alexander Viro
2001-04-19 16:43 ` Linus Torvalds
2001-04-19 17:33 ` Alexander Viro
2001-04-19 17:38 ` Linus Torvalds
2001-04-19 18:24 ` Alexander Viro
2001-04-19 19:26 ` Ulrich Drepper
2001-04-19 19:35 ` Alan Cox
2001-04-19 20:06 ` Ulrich Drepper
2001-04-19 20:11 ` Alan Cox
2001-04-19 20:26 ` Ulrich Drepper
2001-04-19 20:22 ` Ingo Oeser
2001-04-19 20:40 ` Ulrich Drepper
2001-04-19 20:51 ` Linus Torvalds
2001-04-19 21:38 ` Alan Cox
2001-04-19 20:49 ` Linus Torvalds
2001-04-19 21:18 ` Ulrich Drepper
2001-04-19 21:41 ` Linus Torvalds
2001-04-19 22:46 ` Ulrich Drepper
2001-04-20 1:35 ` Alexander Viro
2001-04-20 2:45 ` Ulrich Drepper
2001-04-19 16:43 ` Abramo Bagnara
2001-04-19 20:47 ` Ingo Oeser
2001-04-19 20:54 ` Linus Torvalds
2001-04-19 9:08 ` Ingo Oeser
2001-04-19 11:51 ` Alan Cox
2001-04-19 16:03 ` Linus Torvalds
2001-04-19 16:38 ` Alan Cox
2001-04-19 16:46 ` Linus Torvalds
2001-04-19 17:12 ` Alan Cox
2001-04-19 22:35 ` Rogier Wolff
2001-04-20 9:29 ` Olaf Titz
2001-04-20 14:19 ` Jesse Pollard
2001-04-20 18:36 ` Olaf Titz
2001-04-20 23:33 ` Linus Torvalds
2001-04-21 4:06 ` fd allocation [was: light weight user level semaphores] Edgar Toernig
2001-04-22 9:48 ` Olaf Titz
2001-04-22 11:41 ` light weight user level semaphores Alon Ziv
2001-04-22 12:44 ` Alan Cox
2001-04-22 15:19 ` Alon Ziv
2001-04-22 14:31 ` Alexander Viro
2001-04-22 16:08 ` Alon Ziv
2001-04-22 11:41 ` Alon Ziv
2001-04-22 14:18 ` David Woodhouse
2001-04-23 13:19 ` David Howells
2001-04-23 14:48 ` Alon Ziv
2001-04-23 15:40 ` David Howells
2001-04-21 10:13 ` Olaf Titz
2001-04-23 15:34 ` Jeff Garzik
2001-04-23 19:18 ` Ingo Oeser
2001-04-24 0:19 ` David Wagner [this message]
2001-04-24 0:41 ` Alexander Viro
2001-04-19 19:47 ` Ulrich Drepper
2001-04-19 18:48 ` Olaf Titz
2001-04-19 13:59 George Talbot
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