[PATCH net 2/2] net/smc: dev_put for netdev after usage of ib_query_gid()

[PATCH net 2/2] net/smc: dev_put for netdev after usage of ib_query_gid()

[Ursula Braun]

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@linux.vnet.ibm.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) {
+				lnk->gid = gid;
+				dev_put(gattr.ndev);
+				return 0;
+			}
+			dev_put(gattr.ndev);
 		}
 	}
 	return -ENODEV;
-- 
2.13.5

RE: [PATCH net 1/2] net/smc: replace function pointer get_netdev()

[Parav Pandit]

> -----Original Message-----
> From: Ursula Braun [mailto:ubraun@linux.vnet.ibm.com]
> Sent: Tuesday, October 10, 2017 9:14 AM
> To: davem@davemloft.net
> Cc: netdev@vger.kernel.org; linux-rdma@vger.kernel.org; linux-
> s390@vger.kernel.org; jwi@linux.vnet.ibm.com; schwidefsky@de.ibm.com;
> heiko.carstens@de.ibm.com; raspl@linux.vnet.ibm.com;
> ubraun@linux.vnet.ibm.com; Parav Pandit <parav@mellanox.com>
> Subject: [PATCH net 1/2] net/smc: replace function pointer get_netdev()
> 
> SMC should not open code the function pointer get_netdev of the IB device.
> Replacing ib_query_gid(..., NULL) with ib_query_gid(..., gid_attr) allows access
> to the netdev.
> 
> Signed-off-by: Ursula Braun <ubraun@linux.vnet.ibm.com>
> Suggested-by: Parav Pandit <parav@mellanox.com>
Looks fine to me. Minor nit below.
Reviewed-by: Parav Pandit <parav@mellanox.com>

> ---
>  net/smc/smc_ib.c | 26 +++++++++-----------------
>  1 file changed, 9 insertions(+), 17 deletions(-)
> 
> diff --git a/net/smc/smc_ib.c b/net/smc/smc_ib.c index
> 0b5852299158..b428c0f6c782 100644
> --- a/net/smc/smc_ib.c
> +++ b/net/smc/smc_ib.c
> @@ -369,26 +369,17 @@ void smc_ib_buf_unmap_sg(struct smc_ib_device
> *smcibdev,
> 
>  static int smc_ib_fill_gid_and_mac(struct smc_ib_device *smcibdev, u8 ibport)
> {
> -	struct net_device *ndev;
> +	struct ib_gid_attr gattr;
>  	int rc;
> 
>  	rc = ib_query_gid(smcibdev->ibdev, ibport, 0,
> -			  &smcibdev->gid[ibport - 1], NULL);
> -	/* the SMC protocol requires specification of the roce MAC address;
> -	 * if net_device cannot be determined, it can be derived from gid 0
> -	 */
> -	ndev = smcibdev->ibdev->get_netdev(smcibdev->ibdev, ibport);
> -	if (ndev) {
> -		memcpy(&smcibdev->mac, ndev->dev_addr, ETH_ALEN);
> -		dev_put(ndev);
> -	} else if (!rc) {
> -		memcpy(&smcibdev->mac[ibport - 1][0],
> -		       &smcibdev->gid[ibport - 1].raw[8], 3);
> -		memcpy(&smcibdev->mac[ibport - 1][3],
> -		       &smcibdev->gid[ibport - 1].raw[13], 3);
> -		smcibdev->mac[ibport - 1][0] &= ~0x02;
> -	}
> -	return rc;
> +			  &smcibdev->gid[ibport - 1], &gattr);
> +	if (rc || !gattr.ndev)
> +		return -ENODEV;
> +
> +	memcpy(smcibdev->mac[ibport - 1], gattr.ndev->dev_addr, ETH_ALEN);
> +	dev_put(gattr.ndev);
> +	return 0;
>  }
> 
>  /* Create an identifier unique for this instance of SMC-R.
> @@ -419,6 +410,7 @@ int smc_ib_remember_port_attr(struct smc_ib_device
> *smcibdev, u8 ibport)
>  			   &smcibdev->pattr[ibport - 1]);
>  	if (rc)
>  		goto out;
> +	/* the SMC protocol requires specification of the roce MAC address */
RoCE MAC address

>  	rc = smc_ib_fill_gid_and_mac(smcibdev, ibport);
>  	if (rc)
>  		goto out;
> --
> 2.13.5

RE: [PATCH net 2/2] net/smc: dev_put for netdev after usage of ib_query_gid()

[Parav Pandit]

> -----Original Message-----
> From: Ursula Braun [mailto:ubraun@linux.vnet.ibm.com]
> Sent: Tuesday, October 10, 2017 9:14 AM
> To: davem@davemloft.net
> Cc: netdev@vger.kernel.org; linux-rdma@vger.kernel.org; linux-
> s390@vger.kernel.org; jwi@linux.vnet.ibm.com; schwidefsky@de.ibm.com;
> heiko.carstens@de.ibm.com; raspl@linux.vnet.ibm.com;
> ubraun@linux.vnet.ibm.com; Parav Pandit <parav@mellanox.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@linux.vnet.ibm.com>
Reported-by: Parav Pandit <parav@mellanox.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.