On Sat, Mar 17, 2018 at 10:21:30PM -0400, Zhu Yanjun wrote:
> In mcast recv process, the function skb_clone is used. In fact,
> the refcount can be increased to replace cloning a new skb since
> the original skb will not be modified before it is freed.
>
> This can make the performance better and save the memory.
>
> CC: Srinivas Eeda <srinivas.eeda@xxxxxxxxxx>
> CC: Junxiao Bi <junxiao.bi@xxxxxxxxxx>
> Signed-off-by: Zhu Yanjun <yanjun.zhu@xxxxxxxxxx>
> ---
> drivers/infiniband/sw/rxe/rxe_recv.c | 9 ++++++---
> 1 file changed, 6 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/infiniband/sw/rxe/rxe_recv.c b/drivers/infiniband/sw/rxe/rxe_recv.c
> index 4c3f899..5b8f293 100644
> --- a/drivers/infiniband/sw/rxe/rxe_recv.c
> +++ b/drivers/infiniband/sw/rxe/rxe_recv.c
> @@ -309,10 +309,13 @@ static void rxe_rcv_mcast_pkt(struct rxe_dev *rxe, struct sk_buff *skb)
> continue;
>
> /* if *not* the last qp in the list
> - * make a copy of the skb to post to the next qp
> + * make a reference of the skb to post to the next qp
> */
> - skb_copy = (mce->qp_list.next != &mcg->qp_list) ?
> - skb_clone(skb, GFP_ATOMIC) : NULL;
> + skb_copy = NULL;
> + if (mce->qp_list.next != &mcg->qp_list) {
> + skb_copy = skb;
> + refcount_inc(&skb->users);
> + }
Something with the code after the change doesn't make sense to me, you save
skb in skb_copy (bad name after the change) and then, few lines below skb
is set to skb_copy.
I think with this change we do not really need skb_copy, just do
refcount_inc.
No comments about the idea itself, just the code structure.
Not related to this proposal, while here, can you remove the "if (skb)" in
label err1? looks like kfree_skb takes care of it.
>
> pkt->qp = qp;
> rxe_add_ref(qp);
> --
> 2.7.4
>
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