linux-kernel - Re: [PATCH] scsi: Delete an unnecessary check before the function call "kfree"

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Date:	Sun, 24 Jul 2016 08:51:11 -0400 (EDT)
From:	Laurence Oberman <loberman@...hat.com>
To:	SF Markus Elfring <elfring@...rs.sourceforge.net>
Cc:	linux-scsi@...r.kernel.org, Christoph Hellwig <hch@....de>,
	Hannes Reinecke <hare@...e.de>,
	"James E. J. Bottomley" <jejb@...ux.vnet.ibm.com>,
	"Martin K. Petersen" <martin.petersen@...cle.com>,
	LKML <linux-kernel@...r.kernel.org>,
	kernel-janitors@...r.kernel.org,
	Julia Lawall <julia.lawall@...6.fr>
Subject: Re: [PATCH] scsi: Delete an unnecessary check before the function
 call "kfree"



----- Original Message -----
> From: "SF Markus Elfring" <elfring@...rs.sourceforge.net>
> To: linux-scsi@...r.kernel.org, "Christoph Hellwig" <hch@....de>, "Hannes Reinecke" <hare@...e.de>, "James E. J.
> Bottomley" <jejb@...ux.vnet.ibm.com>, "Martin K. Petersen" <martin.petersen@...cle.com>
> Cc: "LKML" <linux-kernel@...r.kernel.org>, kernel-janitors@...r.kernel.org, "Julia Lawall" <julia.lawall@...6.fr>
> Sent: Sunday, July 24, 2016 8:30:35 AM
> Subject: [PATCH] scsi: Delete an unnecessary check before the function call "kfree"
> 
> From: Markus Elfring <elfring@...rs.sourceforge.net>
> Date: Sun, 24 Jul 2016 14:20:21 +0200
> 
> The kfree() function tests whether its argument is NULL and then
> returns immediately. Thus the test around the call is not needed.
> 
> This issue was detected by using the Coccinelle software.
> 
> Signed-off-by: Markus Elfring <elfring@...rs.sourceforge.net>
> ---
>  drivers/scsi/scsi.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c
> index 1f36aca..1794c0c 100644
> --- a/drivers/scsi/scsi.c
> +++ b/drivers/scsi/scsi.c
> @@ -864,8 +864,7 @@ retry_pg83:
>  		rcu_assign_pointer(sdev->vpd_pg83, vpd_buf);
>  		mutex_unlock(&sdev->inquiry_mutex);
>  		synchronize_rcu();
> -		if (orig_vpd_buf)
> -			kfree(orig_vpd_buf);
> +		kfree(orig_vpd_buf);
>  	}
>  }
>  
> --
> 2.9.2
> 
> --
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> 

Looks fine, small comment is that the function call prior to check in the fucntion sets up variables etc. 
So is more expensive than a simple NULL check prior.

Reviewed-by: Laurence Oberman <loberman@...hat.com>