Re: [PATCH][V2] scsi: cxgb3i: remove redundant null check and kfree on skb

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From	Johannes Thumshirn <jthumshirn@suse.de>
Newsgroups	linux.kernel
Subject	Re: [PATCH][V2] scsi: cxgb3i: remove redundant null check and kfree on skb
Date	Tue, 14 Mar 2017 12:40:04 +0100
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X-Original-Cc	Karen Xie <kxie@chelsio.com>, "James E . J . Bottomley" <jejb@linux.vnet.ibm.com>, "Martin K . Petersen" <martin.petersen@oracle.com>, linux-scsi@vger.kernel.org, kernel-janitors@vger.kernel.org, linux-kernel@vger.kernel.org
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On Tue, Mar 14, 2017 at 10:48:43AM +0000, Colin King wrote:
> From: Colin Ian King <colin.king@canonical.com>
> 
> On the error exit path, skb is always null, so the non-null check
> and __kfree_skb call are redundant.  Remove the redundant code and
> just directly return with the appropriate error return code.
> 
> Detected by CoverityScan, CID#114328 ("Logically Dead Code")
> 
> Signed-off-by: Colin Ian King <colin.king@canonical.com>
> ---
>  drivers/scsi/cxgbi/cxgb3i/cxgb3i.c | 9 ++-------
>  1 file changed, 2 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/scsi/cxgbi/cxgb3i/cxgb3i.c b/drivers/scsi/cxgbi/cxgb3i/cxgb3i.c
> index 1880eb6..3c9f8cf2 100644
> --- a/drivers/scsi/cxgbi/cxgb3i/cxgb3i.c
> +++ b/drivers/scsi/cxgbi/cxgb3i/cxgb3i.c
> @@ -979,14 +979,14 @@ static int init_act_open(struct cxgbi_sock *csk)
>  	csk->atid = cxgb3_alloc_atid(t3dev, &t3_client, csk);
>  	if (csk->atid < 0) {
>  		pr_err("NO atid available.\n");
> -		goto rel_resource;
> +		return -EINVAL;
>  	}
>  	cxgbi_sock_set_flag(csk, CTPF_HAS_ATID);
>  	cxgbi_sock_get(csk);
>  
>  	skb = alloc_wr(sizeof(struct cpl_act_open_req), 0, GFP_KERNEL);
>  	if (!skb)
> -		goto rel_resource;
> +		return -ENOMEM;

I don't think that's correct, not that it was before. cxgbi_sock_get(csk) does a
kref_get(&csk->refcnt), so this will at lease leak a kref. It will also "leak"
the atids_in_use in cxgb3_alloc_atid() as there's a call to cxgb3_free_atid()
missing. Looks like the complete cleanup path is worng here.

But I'd prefer having Karen or someone else at Chelsio confirm my assumptions.

Thanks,
	Johannes

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Johannes Thumshirn                                          Storage
jthumshirn@suse.de                                +49 911 74053 689
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[PATCH][V2] scsi: cxgb3i: remove redundant null check and kfree on skb Colin King <colin.king@canonical.com> - 2017-03-14 11:50 +0100
  Re: [PATCH][V2] scsi: cxgb3i: remove redundant null check and kfree  on skb Dan Carpenter <dan.carpenter@oracle.com> - 2017-03-14 12:20 +0100
  Re: [PATCH][V2] scsi: cxgb3i: remove redundant null check and kfree  on skb Johannes Thumshirn <jthumshirn@suse.de> - 2017-03-14 12:40 +0100

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