From: Stephen Hemminger <stephen@networkplumber.org>
To: NAGENDRA BALAGANI <nagendra.balagani@oracle.com>
Cc: "dev@dpdk.org" <dev@dpdk.org>,
Kapil Kumar Jain <kapil.k.jain@oracle.com>
Subject: Re: Strange behavior with rte_pktmbuf_clone cal
Date: Fri, 23 Dec 2022 08:43:17 -0800 [thread overview]
Message-ID: <20221223084317.580f966e@hermes.local> (raw)
In-Reply-To: <DM6PR10MB4124C6E61BBC5AD77E5F206696E99@DM6PR10MB4124.namprd10.prod.outlook.com>
On Fri, 23 Dec 2022 07:00:40 +0000
NAGENDRA BALAGANI <nagendra.balagani@oracle.com> wrote:
> Hi,
>
> I am seeing strange behavior where rte_pktmbuf_clone is not giving desired result.
> Here is the detailed info, in my dpdk application , once I received the packet info in mbuf, I need to send the same packet to two destinations, the sequence I should follow is,
>
> (i) First, Tunnel the packet to one of desired destination, so I created the shallow copy using rte_pktmbuf_clone, had another mbuf for Outer IP Header for IPinIP tunnel and sent to NIC.
>
> (ii) Second, I need to modify the source and destination ip addresses of the packet and send out.
As you showed, that won't work like you think.
A shallow clone means that both versions share the same data area.
If you modify one one instance both change.
The best practice is to consider a clone (or any mbuf with refcount > 1) as read only.
prev parent reply other threads:[~2022-12-23 16:43 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-12-23 7:00 NAGENDRA BALAGANI
2022-12-23 16:25 ` Konstantin Ananyev
2022-12-23 16:43 ` Stephen Hemminger [this message]
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