linux-kernel - Re: [patch] x86, bts: fix unlock problem in ds.c

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Message-ID: <7c86c4470811201314q564b64c0i99f3d9865d9cc8f0@mail.gmail.com>
Date:	Thu, 20 Nov 2008 22:14:40 +0100
From:	"stephane eranian" <eranian@...glemail.com>
To:	"Markus Metzger" <markus.t.metzger@...glemail.com>
Cc:	lkml <linux-kernel@...r.kernel.org>,
	work <markus.t.metzger@...el.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	"Thomas Gleixner" <tglx@...utronix.de>,
	"Ingo Molnar" <mingo@...e.hu>
Subject: Re: [patch] x86, bts: fix unlock problem in ds.c

Markus,

I think this patch is not quite right. You don't want to go out via out_unlock
because you're going to call ds_put_context)() when you did not invoke the
matching ds_get_context() (hidden in ds_alloc_context). It happens later in
the ds_request() function.


On Sat, Nov 15, 2008 at 11:00 AM, Markus Metzger
<markus.t.metzger@...glemail.com> wrote:
> Fix a problem where ds_request() returned an error without releasing the
> ds lock.
>
> Reported-by: Stephane Eranian <eranian@...il.com>
> Signed-off-by: Markus Metzger <markus.t.metzger@...il.com>
> ---
>
> Index: gits/arch/x86/kernel/ds.c
> ===================================================================
> --- gits.orig/arch/x86/kernel/ds.c      2008-11-15 10:51:51.000000000 +0100
> +++ gits/arch/x86/kernel/ds.c   2008-11-15 10:53:43.000000000 +0100
> @@ -384,8 +384,9 @@
>
>        spin_lock(&ds_lock);
>
> +       error = -EPERM;
>        if (!check_tracer(task))
> -               return -EPERM;
> +               goto out_unlock;
>
>        error = -ENOMEM;
>        context = ds_alloc_context(task);
>
>
>
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