netdev - RE: [PATCH net 2/2] net/smc: dev_put for netdev after usage of ib_query

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Date:   Tue, 10 Oct 2017 17:09:08 +0000
From:   Parav Pandit <parav@...lanox.com>
To:     Ursula Braun <ubraun@...ux.vnet.ibm.com>,
        "davem@...emloft.net" <davem@...emloft.net>
CC:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-rdma@...r.kernel.org" <linux-rdma@...r.kernel.org>,
        "linux-s390@...r.kernel.org" <linux-s390@...r.kernel.org>,
        "jwi@...ux.vnet.ibm.com" <jwi@...ux.vnet.ibm.com>,
        "schwidefsky@...ibm.com" <schwidefsky@...ibm.com>,
        "heiko.carstens@...ibm.com" <heiko.carstens@...ibm.com>,
        "raspl@...ux.vnet.ibm.com" <raspl@...ux.vnet.ibm.com>
Subject: RE: [PATCH net 2/2] net/smc: dev_put for netdev after usage of
 ib_query_gid()



> -----Original Message-----
> From: Ursula Braun [mailto:ubraun@...ux.vnet.ibm.com]
> Sent: Tuesday, October 10, 2017 9:14 AM
> To: davem@...emloft.net
> Cc: netdev@...r.kernel.org; linux-rdma@...r.kernel.org; linux-
> s390@...r.kernel.org; jwi@...ux.vnet.ibm.com; schwidefsky@...ibm.com;
> heiko.carstens@...ibm.com; raspl@...ux.vnet.ibm.com;
> ubraun@...ux.vnet.ibm.com; Parav Pandit <parav@...lanox.com>
> Subject: [PATCH net 2/2] net/smc: dev_put for netdev after usage of
> ib_query_gid()
> 
> For ROCEs ib_query_gid() takes a reference count on the net_device.
> This reference count must be decreased by the caller.
> 
> Signed-off-by: Ursula Braun <ubraun@...ux.vnet.ibm.com>
Reported-by: Parav Pandit <parav@...lanox.com>

> ---
>  net/smc/smc_core.c | 11 +++++++----
>  1 file changed, 7 insertions(+), 4 deletions(-)
> 
> diff --git a/net/smc/smc_core.c b/net/smc/smc_core.c index
> 20b66e79c5d6..e93a31ec3cc2 100644
> --- a/net/smc/smc_core.c
> +++ b/net/smc/smc_core.c
> @@ -380,10 +380,13 @@ static int smc_link_determine_gid(struct
> smc_link_group *lgr)
>  		if (ib_query_gid(lnk->smcibdev->ibdev, lnk->ibport, i, &gid,
>  				 &gattr))
>  			continue;
> -		if (gattr.ndev &&
> -		    (vlan_dev_vlan_id(gattr.ndev) == lgr->vlan_id)) {
> -			lnk->gid = gid;
> -			return 0;
> +		if (gattr.ndev) {
> +			if (vlan_dev_vlan_id(gattr.ndev) == lgr->vlan_id) {

This needs to be changed to 
If (gattr.ndev) {
	if (is_vlan_dev(gattr.ndev)) && 
	    vlan_dev_vlan_id(gattr.ndev) == lgr->vlan_id) {
	...
}

Without this check, on vlan disabled kernel at compile time, kernel will crash on vlan_dev_vlan_id().
Please fix this part, rest code looks fine.