From: Andrew Morton <akpm@osdl.org>
To: Oleg Nesterov <oleg@tv-sign.ru>
Cc: ebiederm@xmission.com, torvalds@osdl.org,
linux-kernel@vger.kernel.org, janak@us.ibm.com,
viro@ftp.linux.org.uk, hch@lst.de, mtk-manpages@gmx.net,
ak@muc.de, paulus@samba.org
Subject: Re: [PATCH] unshare: Use rcu_assign_pointer when setting sighand
Date: Fri, 17 Mar 2006 12:56:07 -0800 [thread overview]
Message-ID: <20060317125607.78a5dbe4.akpm@osdl.org> (raw)
In-Reply-To: <441AF596.F6E66BC9@tv-sign.ru>
Oleg Nesterov <oleg@tv-sign.ru> wrote:
>
> "Eric W. Biederman" wrote:
> >
> > @@ -1573,7 +1573,7 @@ asmlinkage long sys_unshare(unsigned lon
> >
> > if (new_sigh) {
> > sigh = current->sighand;
> > - current->sighand = new_sigh;
> > + rcu_assign_pointer(current->sighand, new_sigh);
> > new_sigh = sigh;
> > }
>
> Isn't it better to just replace this code with
> 'BUG_ON(new_sigh != NULL)' ?
>
> It is never executed, but totally broken, afaics.
> task_lock() has nothing to do with ->sighand changing.
>
/*
* Unsharing of sighand for tasks created with CLONE_SIGHAND is not
* supported yet
*/
static int unshare_sighand(unsigned long unshare_flags, struct sighand_struct **new_sighp)
It's all just a place-holder at present.
If we don't plan on ever supporting unshare(CLONE_SIGHAND) we should take
that code out and make it return EINVAL. Right now.
And because we don't presently support CLONE_SIGHAND we should return
EINVAL if it's set. Right now.
And we should change sys_unshare() to reject not-understood flags. Right
now.
If we don't do these things we'll silently break 2.6.16-back-compatibility
of applications which are coded for future kernels.
next prev parent reply other threads:[~2006-03-17 20:59 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-03-16 16:49 [PATCH] unshare: Cleanup up the sys_unshare interface before we are committed Eric W. Biederman
2006-03-16 17:31 ` [PATCH] unshare: Use rcu_assign_pointer when setting sighand Eric W. Biederman
2006-03-17 6:48 ` Paul E. McKenney
2006-03-17 17:44 ` Oleg Nesterov
2006-03-17 20:56 ` Andrew Morton [this message]
2006-03-18 13:12 ` Oleg Nesterov
2006-03-18 15:43 ` Janak Desai
2006-03-18 17:24 ` Oleg Nesterov
2006-03-18 17:41 ` [PATCH] for 2.6.16, disable unshare_vm() Oleg Nesterov
2006-03-18 18:10 ` Linus Torvalds
2006-03-18 18:29 ` Ulrich Drepper
2006-03-18 18:48 ` Janak Desai
2016-03-14 13:15 ` unshare(CLONE_VM) Re: [PATCH] unshare: Use rcu_assign_pointer when setting sighand Julian Smith
2016-03-14 18:35 ` Linus Torvalds
2006-03-18 13:13 ` [PATCH] implement unshare(CLONE_SIGHAND) for single-thread case Oleg Nesterov
2006-03-18 15:10 ` [PATCH] unshare: Error if passed unsupported flags Eric W. Biederman
2006-03-18 15:33 ` Janak Desai
2006-03-18 16:29 ` [PATCH] unshare: Use rcu_assign_pointer when setting sighand Janak Desai
2006-03-16 19:40 ` [PATCH] unshare: Cleanup up the sys_unshare interface before we are committed Michael Kerrisk
2006-03-16 20:33 ` Andrew Morton
2006-03-16 20:41 ` Linus Torvalds
2006-03-16 21:58 ` Eric W. Biederman
2006-03-16 22:19 ` Andrew Morton
2006-03-16 21:36 ` Janak Desai
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