netdev - Re: [PATCH] net: caif: chnl_net: remove unnecessary null check in chnl_recv

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Message-ID: <20171030213357.Horde.6OOG7UXJzbPReRCnj5zqscs@gator4166.hostgator.com>
Date:   Mon, 30 Oct 2017 21:33:57 -0500
From:   "Gustavo A. R. Silva" <garsilva@...eddedor.com>
To:     Dmitry Tarnyagin <dmitry.tarnyagin@...kless.no>,
        "David S. Miller" <davem@...emloft.net>
Cc:     netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] net: caif: chnl_net: remove unnecessary null check in
 chnl_recv_cb


Quoting "Gustavo A. R. Silva" <garsilva@...eddedor.com>:

> Hi,
>
> Quoting "Gustavo A. R. Silva" <garsilva@...eddedor.com>:
>
>> container_of is never null, so this null check is unnecessary.
>>
>> This code was detected with the help of Coccinelle.
>>
>> Signed-off-by: Gustavo A. R. Silva <garsilva@...eddedor.com>
>> ---
>> net/caif/chnl_net.c | 2 --
>> 1 file changed, 2 deletions(-)
>>
>> diff --git a/net/caif/chnl_net.c b/net/caif/chnl_net.c
>> index 922ac1d..489298d 100644
>> --- a/net/caif/chnl_net.c
>> +++ b/net/caif/chnl_net.c
>> @@ -77,8 +77,6 @@ static int chnl_recv_cb(struct cflayer *layr,  
>> struct cfpkt *pkt)
>> 	u8 buf;
>>
>> 	priv = container_of(layr, struct chnl_net, chnl);
>> -	if (!priv)
>> -		return -EINVAL;
>>
>> 	skb = (struct sk_buff *) cfpkt_tonative(pkt);
>>
>> --
>> 2.7.4
>
> Please, ignore this patch.
>
> I just realized that function chnl_recv_cb is being called only  
> during initialization:
>
> chnl_init_module() -> rtnl_link_register() -> ipcaif_net_setup() ->  
> chnl_recv_cb():
>

Well, here ipcaif_net_setup stores a pointer to chnl_recv_cb in a  
structure. It doesn't call it.

> static void ipcaif_net_setup(struct net_device *dev)
> {
> [...]
> 	priv = netdev_priv(dev);
> 	priv->chnl.receive = chnl_recv_cb;
>
> [...]
> }
>
> static struct rtnl_link_ops ipcaif_link_ops __read_mostly = {
> 	.kind		= "caif",
> 	.priv_size	= sizeof(struct chnl_net),
> 	.setup		= ipcaif_net_setup,
> 	.maxtype	= IFLA_CAIF_MAX,
> 	.policy		= ipcaif_policy,
> 	.newlink	= ipcaif_newlink,
> 	.changelink	= ipcaif_changelink,
> 	.get_size	= ipcaif_get_size,
> 	.fill_info	= ipcaif_fill_info,
>
> };
>
> static int __init chnl_init_module(void)
> {
> 	return rtnl_link_register(&ipcaif_link_ops);
> }
>

--
Gustavo A. R. Silva