netdev - RE: [PATCH net-next 01/10] net/smc: add missing dev

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Date:   Mon, 2 Oct 2017 20:39:56 +0000
From:   Parav Pandit <parav@...lanox.com>
To:     Parav Pandit <parav@...lanox.com>,
        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-next 01/10] net/smc: add missing dev_put

> -----Original Message-----
> From: linux-rdma-owner@...r.kernel.org [mailto:linux-rdma-
> owner@...r.kernel.org] On Behalf Of Parav Pandit
> Sent: Monday, October 02, 2017 3:36 PM
> To: Ursula Braun <ubraun@...ux.vnet.ibm.com>; 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
> Subject: RE: [PATCH net-next 01/10] net/smc: add missing dev_put
> 
> Hi Ursula, Dave, Hans,
> 
> > -----Original Message-----
> > From: linux-rdma-owner@...r.kernel.org [mailto:linux-rdma-
> > owner@...r.kernel.org] On Behalf Of Ursula Braun
> > Sent: Wednesday, September 20, 2017 6:58 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
> > Subject: [PATCH net-next 01/10] net/smc: add missing dev_put
> >
> > From: Hans Wippel <hwippel@...ux.vnet.ibm.com>
> >
> > In the infiniband part, SMC currently uses get_netdev which calls
> > dev_hold on the returned net device. However, the SMC code never calls
> > dev_put on that net device resulting in a wrong reference count.
> >
> > This patch adds a dev_put after the usage of the net device to fix the issue.
> >
> > Signed-off-by: Hans Wippel <hwippel@...ux.vnet.ibm.com>
> > Signed-off-by: Ursula Braun <ubraun@...ux.vnet.ibm.com>
> > ---
> >  net/smc/smc_ib.c | 1 +
> >  1 file changed, 1 insertion(+)
> >
> > diff --git a/net/smc/smc_ib.c b/net/smc/smc_ib.c index
> > 547e0e113b17..0b5852299158 100644
> > --- a/net/smc/smc_ib.c
> > +++ b/net/smc/smc_ib.c
> > @@ -380,6 +380,7 @@ static int smc_ib_fill_gid_and_mac(struct
> > smc_ib_device *smcibdev, u8 ibport)
> >  	ndev = smcibdev->ibdev->get_netdev(smcibdev->ibdev, ibport);
> >  	if (ndev) {
> >  		memcpy(&smcibdev->mac, ndev->dev_addr, ETH_ALEN);
> > +		dev_put(ndev);
> 
> I am sorry for providing late comments. smc_ib_fill_gid_and_mac() is not coded
> correctly.
> Few fixes are needed.
> 1. ULP such as SMC should not open code/deference any function pointer like
> get_netdev() of the IB device.
> 2. Replace ib_query_gid(..., NULL)
> With
> ib_query_gid(..., gid_attr);
> 
> Use gid_attr.ndev to get the MAC address.
> Do dev_put(gid_attr.ndev);
> 
> Code should look like below,
> 
> struct ib_gid_attr gid_attr;
> 
> rc = ib_query_gid(..., &gid_attr);
> if (rc || !gid_addr.ndev)
> 	return -ENODEV;
> else
> 	memcpy(smcibdev->mac, ndev->dev_addr, ETH_ALEN);
> dev_put(gid_addr.ndev);
> --

Also,
smc_link_determine_gid() doesn't do dev_put(gattr.ndev) in for loop.
Please fix it as well.