From: BAIN <bainonline@gmail.com>
To: linux-kernel@vger.kernel.org
Subject: Re: set_fs() preemption safety? [was sys_fs() safety oops !]
Date: Sun, 4 Jul 2004 11:14:27 -0400 [thread overview]
Message-ID: <2ff2162804070408142348de6b@mail.gmail.com> (raw)
In-Reply-To: <200407041653.55816.arnd@arndb.de>
> > is the following block safe to be used in preemptible kernels?
> >
> > old_fs = get_fs();
> > set_fs(KERNEL_DS);
> >
> > do_your_things here; (usually call sys calls stuff from kernel space)
> >
> > set_fs(old_fs);
>
> On most architectures, this should not be a problem, because set_fs()
> only modifies the state of the current task, not any actual processor
> registers as the name suggests.
>
> However, on s390 the state is actually kept in cpu control register cr7
> and not in the task_struct. Martin, can you comment on how this is
> maintained over a schedule() or if this is a real bug?
Ok this is new info for me,...
I was under impression that i am banned from calling schedule between
the two calls to set_fs.
This answers my question. Thanks,
BAIN
prev parent reply other threads:[~2004-07-04 15:14 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-07-04 14:36 set_fs() preemption safety? [was sys_fs() safety oops !] BAIN
2004-07-04 14:53 ` Arnd Bergmann
2004-07-04 15:14 ` BAIN [this message]
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