linux-kernel - Re: [PATCH] mcheck: Correction to a missing return value from misc

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Date:	Fri, 04 Mar 2011 16:44:16 +0000
From:	"J.P. Lacerda" <jpl@...ethink.co.uk>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Johan Wessfeldt <johan.wessfeldt@...il.com>, tglx@...utronix.de,
	mingo@...hat.com, x86@...nel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mcheck: Correction to a missing return value from
 misc_register

Andrew,

Where can a memory leak occur in sysdev_class_register()?
If one does occur, should the fix not be applied to
sysdev_class_register(), as opposed to mcheck_init_device()?

Thanks,

J.P.

On Wed, 2011-03-02 at 16:06 -0800, Andrew Morton wrote:
> On Mon, 28 Feb 2011 12:19:04 +0100
> Johan Wessfeldt <johan.wessfeldt@...il.com> wrote:
> 
> > Return value from misc_register was not handled correctly
> > in mcheck_init_device()
> > 
> > Signed-off-by: Johan Wessfeldt <johan.wessfeldt@...il.com>
> > ---
> >  arch/x86/kernel/cpu/mcheck/mce.c |    2 +-
> >  1 files changed, 1 insertions(+), 1 deletions(-)
> > 
> > diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c
> > index d916183..7274a11 100644
> > --- a/arch/x86/kernel/cpu/mcheck/mce.c
> > +++ b/arch/x86/kernel/cpu/mcheck/mce.c
> > @@ -2140,7 +2140,7 @@ static __init int mcheck_init_device(void)
> >  	}
> >  
> >  	register_hotcpu_notifier(&mce_cpu_notifier);
> > -	misc_register(&mce_log_device);
> > +	err = misc_register(&mce_log_device);
> >  
> >  	return err;
> >  }
> 
> It should be fixed, but not that way.  If misc_register() fails here,
> mcheck_init_device() should undo all the things which it just did.
> 
> And the memory leak which occurs if sysdev_class_register() fails and
> the memory and other resource leaks which occur if mce_create_device()
> fails should be fixed too.
> 
> mcheck_init_device() a rather optimistic function.
> --
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