[PATCH 1/1] IB/rxe: remove unnecessary skb_clone in xmit

Zhu Yanjun
2018-01-05T08:19:51Z

In xmit, there is a skb_clone. This function copies the struct sk_buff.
And some parameters are changed to the new skb. Then the new skb is sent
while the old skb is freed.

While the function skb_clone is removed, the parameter changes are made on
the old skb, then the old skb is sent. It can also work well.

The following tests are made.

server client
--------- ---------
|1.1.1.1|<----rxe-channel--->|1.1.1.2|
--------- ---------

On server: rping -s -a 1.1.1.1 -v -C 1000 -S 512
On client: rping -c -a 1.1.1.1 -v -C 1000 -S 512

The kernel config CONFIG_DEBUG_KMEMLEAK is enabled on both server
and client.

This test runs for several hours. There is no memory leak and the whole
system can work well.

CC: Srinivas Eeda <srinivas.eeda-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
CC: Joe Jin <joe.jin-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
CC: Junxiao Bi <junxiao.bi-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
Signed-off-by: Zhu Yanjun <yanjun.zhu-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
---
drivers/infiniband/sw/rxe/rxe_net.c | 16 +++++-----------
1 file changed, 5 insertions(+), 11 deletions(-)

diff --git a/drivers/infiniband/sw/rxe/rxe_net.c b/drivers/infiniband/sw/rxe/rxe_net.c
index 59dee10..5fc6bb5 100644
--- a/drivers/infiniband/sw/rxe/rxe_net.c
+++ b/drivers/infiniband/sw/rxe/rxe_net.c
@@ -452,31 +452,26 @@ static void rxe_skb_tx_dtor(struct sk_buff *skb)

int rxe_send(struct rxe_dev *rxe, struct rxe_pkt_info *pkt, struct sk_buff *skb)
{
- struct sk_buff *nskb;
struct rxe_av *av;
int err;

av = rxe_get_av(pkt);

- nskb = skb_clone(skb, GFP_ATOMIC);
- if (!nskb)
- return -ENOMEM;
-
- nskb->destructor = rxe_skb_tx_dtor;
- nskb->sk = pkt->qp->sk->sk;
+ skb->destructor = rxe_skb_tx_dtor;
+ skb->sk = pkt->qp->sk->sk;

rxe_add_ref(pkt->qp);
atomic_inc(&pkt->qp->skb_out);

if (av->network_type == RDMA_NETWORK_IPV4) {
- err = ip_local_out(dev_net(skb_dst(skb)->dev), nskb->sk, nskb);
+ err = ip_local_out(dev_net(skb_dst(skb)->dev), skb->sk, skb);
} else if (av->network_type == RDMA_NETWORK_IPV6) {
- err = ip6_local_out(dev_net(skb_dst(skb)->dev), nskb->sk, nskb);
+ err = ip6_local_out(dev_net(skb_dst(skb)->dev), skb->sk, skb);
} else {
pr_err("Unknown layer 3 protocol: %d\n", av->network_type);
atomic_dec(&pkt->qp->skb_out);
rxe_drop_ref(pkt->qp);
- kfree_skb(nskb);
+ kfree_skb(skb);
return -EINVAL;
}

@@ -485,7 +480,6 @@ int rxe_send(struct rxe_dev *rxe, struct rxe_pkt_info *pkt, struct sk_buff *skb)
return -EAGAIN;
}

- kfree_skb(skb);
return 0;
}

--
2.7.4