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From: "Tan, Jianfeng" <jianfeng.tan@intel.com>
To: "Chen, Junjie J" <junjie.j.chen@intel.com>,
	"yliu@fridaylinux.org" <yliu@fridaylinux.org>,
	"maxime.coquelin@redhat.com" <maxime.coquelin@redhat.com>
Cc: "dev@dpdk.org" <dev@dpdk.org>,
	"Chen, Junjie J" <junjie.j.chen@intel.com>
Subject: Re: [dpdk-dev] [PATCH] vhost: dequeue zero copy should restore mbuf	before return to pool
Date: Wed, 17 Jan 2018 07:29:19 +0000	[thread overview]
Message-ID: <ED26CBA2FAD1BF48A8719AEF02201E36513C18B1@SHSMSX103.ccr.corp.intel.com> (raw)
In-Reply-To: <1516185726-31797-1-git-send-email-junjie.j.chen@intel.com>



> -----Original Message-----
> From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Junjie Chen
> Sent: Wednesday, January 17, 2018 6:42 PM
> To: yliu@fridaylinux.org; maxime.coquelin@redhat.com
> Cc: dev@dpdk.org; Chen, Junjie J
> Subject: [dpdk-dev] [PATCH] vhost: dequeue zero copy should restore mbuf
> before return to pool
> 
> dequeue zero copy change buf_addr and buf_iova of mbuf, and return
> to mbuf pool without restore them, it breaks vm memory if others allocate
> mbuf from same pool since mbuf reset doesn't reset buf_addr and buf_iova.
> 
> Signed-off-by: Junjie Chen <junjie.j.chen@intel.com>
> ---
>  lib/librte_vhost/virtio_net.c | 21 +++++++++++++++++++++
>  1 file changed, 21 insertions(+)
> 
> diff --git a/lib/librte_vhost/virtio_net.c b/lib/librte_vhost/virtio_net.c
> index 568ad0e..e9aaf6d 100644
> --- a/lib/librte_vhost/virtio_net.c
> +++ b/lib/librte_vhost/virtio_net.c
> @@ -1158,6 +1158,26 @@ mbuf_is_consumed(struct rte_mbuf *m)
>  	return true;
>  }
> 
> +
> +static __rte_always_inline void
> +restore_mbuf(struct rte_mbuf *m)
> +{
> +	uint32_t mbuf_size, priv_size;
> +
> +	while (m) {
> +		priv_size = rte_pktmbuf_priv_size(m->pool);
> +		mbuf_size = sizeof(struct rte_mbuf) + priv_size;
> +		/* start of buffer is after mbuf structure and priv data */
> +		m->priv_size = priv_size;

I don't think we need to restore priv_size. Refer to its definition in rte_mbuf:
    "Size of the application private data. In case of an indirect mbuf, it stores the direct mbuf private data size."

Thanks,
Jianfeng

> +
> +		m->buf_addr = (char *)m + mbuf_size;
> +		m->buf_iova = rte_mempool_virt2iova(m) + mbuf_size;
> +		m->data_off = RTE_MIN(RTE_PKTMBUF_HEADROOM,
> +			(uint16_t)m->buf_len);
> +		m = m->next;
> +	}
> +}
> +
>  uint16_t
>  rte_vhost_dequeue_burst(int vid, uint16_t queue_id,
>  	struct rte_mempool *mbuf_pool, struct rte_mbuf **pkts, uint16_t
> count)
> @@ -1209,6 +1229,7 @@ rte_vhost_dequeue_burst(int vid, uint16_t
> queue_id,
>  				nr_updated += 1;
> 
>  				TAILQ_REMOVE(&vq->zmbuf_list, zmbuf,
> next);
> +				restore_mbuf(zmbuf->mbuf);
>  				rte_pktmbuf_free(zmbuf->mbuf);
>  				put_zmbuf(zmbuf);
>  				vq->nr_zmbuf -= 1;
> --
> 2.0.1

next prev parent reply	other threads:[~2018-01-17  7:29 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-01-17 10:42 Junjie Chen
2018-01-17  7:29 ` Tan, Jianfeng [this message]
2018-01-17  8:10   ` Chen, Junjie J
2018-01-17 15:45 ` [dpdk-dev] [PATCH v2] " Junjie Chen
2018-01-18  8:44   ` Maxime Coquelin
2018-01-18 13:16     ` Yuanhan Liu

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