linux-kernel - Re: [PATCH] oprofile, x86: fix init

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Message-ID: <20100901095117.GA4246@elte.hu>
Date:	Wed, 1 Sep 2010 11:51:17 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	Robert Richter <robert.richter@....com>
Cc:	Will Deacon <will.deacon@....com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	Matt Fleming <matt@...sole-pimps.org>,
	Peter Zijlstra <peterz@...radead.org>
Subject: Re: [PATCH] oprofile, x86: fix init_sysfs error handling


* Robert Richter <robert.richter@....com> wrote:

> On 31.08.10 05:31:29, Will Deacon wrote:
> > > For x86 wont change the code (actually I found a bug in the init_sysfs
> > > error handler for which I will send a fix). Just wanted to get your
> > > confirmation in case I was missing something that x86 is not affected.
> > > I will apply the first 2 patches, no need to resubmit.
> 
> This is the patch, applied to:
> 
>  git://git.kernel.org/pub/scm/linux/kernel/git/rric/oprofile.git urgent
> 
> -Robert
> 
> --
> 
> >From 10f0412f57f2a76a90eff4376f59cbb0a39e4e18 Mon Sep 17 00:00:00 2001
> From: Robert Richter <robert.richter@....com>
> Date: Mon, 30 Aug 2010 10:56:18 +0200
> Subject: [PATCH] oprofile, x86: fix init_sysfs error handling
> 
> On failure init_sysfs() might not properly free resources. The error
> code of the function is not checked. And, when reinitializing the exit
> function might be called twice. This patch fixes all this.
> 
> Cc: stable@...nel.org
> Signed-off-by: Robert Richter <robert.richter@....com>
> ---
>  arch/x86/oprofile/nmi_int.c |   16 +++++++++++++---
>  1 files changed, 13 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/x86/oprofile/nmi_int.c b/arch/x86/oprofile/nmi_int.c
> index f6b48f6..73a41d3 100644
> --- a/arch/x86/oprofile/nmi_int.c
> +++ b/arch/x86/oprofile/nmi_int.c
> @@ -568,8 +568,13 @@ static int __init init_sysfs(void)
>  	int error;
>  
>  	error = sysdev_class_register(&oprofile_sysclass);
> -	if (!error)
> -		error = sysdev_register(&device_oprofile);
> +	if (error)
> +		return error;
> +
> +	error = sysdev_register(&device_oprofile);
> +	if (error)
> +		sysdev_class_unregister(&oprofile_sysclass);
> +
>  	return error;
>  }
>  
> @@ -695,6 +700,8 @@ int __init op_nmi_init(struct oprofile_operations *ops)
>  	char *cpu_type = NULL;
>  	int ret = 0;
>  
> +	using_nmi = 0;
> +
>  	if (!cpu_has_apic)
>  		return -ENODEV;
>  
> @@ -774,7 +781,10 @@ int __init op_nmi_init(struct oprofile_operations *ops)
>  
>  	mux_init(ops);
>  
> -	init_sysfs();
> +	ret = init_sysfs();

FYI, this causes a build error if CONFIG_PM is off:

   arch/x86/oprofile/nmi_int.c:784: error: expected expression before ‘do’

Due to this assymetric form of the wrapper:

  #define init_sysfs() do { } while (0)

The wrapper should be changed to return 0 i suspect, via something like 
this:

  static inline int init_sysfs(void) { return 0; }

(untested)

Thanks,

	Ingo
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