linux-kernel - Re: [PATCH 3/3] drivers/misc/sgi-gru: fix return of error

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Date:	Sat, 26 Sep 2015 07:44:33 -0500
From:	Dimitri Sivanich <sivanich@....com>
To:	Sudip Mukherjee <sudipm.mukherjee@...il.com>
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Arnd Bergmann <arnd@...db.de>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/3] drivers/misc/sgi-gru: fix return of error

Acked-by: Dimitri Sivanich <sivanich@....com>

On Mon, Sep 21, 2015 at 03:48:19PM +0530, Sudip Mukherjee wrote:
> If kzalloc() fails then gms is NULL and we are returning NULL, but the
> functions which called this function gru_register_mmu_notifier() are not
> expecting NULL as the return. They are expecting either a valid pointer
> or the error code in ERR_PTR.
> 
> Signed-off-by: Sudip Mukherjee <sudip@...torindia.org>
> ---
> 
> The patch at https://patchwork.kernel.org/patch/6394911/ is not applied
> and not relevant now as gms is checked before gru_dbg. But the idea for
> this patch was obtained from that one.
> 
>  drivers/misc/sgi-gru/grutlbpurge.c | 20 ++++++++++----------
>  1 file changed, 10 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/misc/sgi-gru/grutlbpurge.c b/drivers/misc/sgi-gru/grutlbpurge.c
> index 757a8e9..e936d43 100644
> --- a/drivers/misc/sgi-gru/grutlbpurge.c
> +++ b/drivers/misc/sgi-gru/grutlbpurge.c
> @@ -306,16 +306,16 @@ struct gru_mm_struct *gru_register_mmu_notifier(void)
>  		atomic_inc(&gms->ms_refcnt);
>  	} else {
>  		gms = kzalloc(sizeof(*gms), GFP_KERNEL);
> -		if (gms) {
> -			STAT(gms_alloc);
> -			spin_lock_init(&gms->ms_asid_lock);
> -			gms->ms_notifier.ops = &gru_mmuops;
> -			atomic_set(&gms->ms_refcnt, 1);
> -			init_waitqueue_head(&gms->ms_wait_queue);
> -			err = __mmu_notifier_register(&gms->ms_notifier, current->mm);
> -			if (err)
> -				goto error;
> -		}
> +		if (!gms)
> +			return ERR_PTR(-ENOMEM);
> +		STAT(gms_alloc);
> +		spin_lock_init(&gms->ms_asid_lock);
> +		gms->ms_notifier.ops = &gru_mmuops;
> +		atomic_set(&gms->ms_refcnt, 1);
> +		init_waitqueue_head(&gms->ms_wait_queue);
> +		err = __mmu_notifier_register(&gms->ms_notifier, current->mm);
> +		if (err)
> +			goto error;
>  	}
>  	if (gms)
>  		gru_dbg(grudev, "gms %p, refcnt %d\n", gms,
> -- 
> 1.9.1
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