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From: Kevin Traynor <ktraynor@redhat.com>
To: Tiago Lam <tiago.lam@intel.com>, dev@dpdk.org
Cc: ferruh.yigit@intel.com, linville@tuxdriver.com
Subject: Re: [dpdk-dev] [PATCH v2 1/3] net/af_packet: set_mtu() decrements sockaddr twice
Date: Tue, 20 Nov 2018 10:29:31 +0000	[thread overview]
Message-ID: <4419c3e1-d94c-8cde-cf55-0e54a255b8c4@redhat.com> (raw)
In-Reply-To: <1542709592-215007-1-git-send-email-tiago.lam@intel.com>

On 11/20/2018 10:26 AM, Tiago Lam wrote:
> When setting the MTU, eth_dev_mtu_set() is called to validate the
> provided MTU. As part of that, it calculates the useful area to store
> data and compares it against the MTU, to guarantee that there's enough
> space to store the data. It calculates that as:
>     "tp_frame_size - TPACKET2_HDRLEN - sizeof(struct sockaddr_ll)"
> 
> However, the TPACKET2_HDRLEN macro already increaments sizeof(struct
> sockaddr_ll) internally, meaning the useuful area of data above will
> have sizeof(struct sockaddr_ll) decremented twice.
> 
> Instead, the useful area of data should be calculated as:
>     "tp_frame_size - TPACKET2_HDRLEN"
> 
> This makes sure that there's enough useful area to fit the provided MTU
> after excluding tpacket2_hdr and sockaddr_ll.
> 
> Fixes: cc68ac4 ("net/af_packet: support MTU change")
> 

It should be for stable also?

> Signed-off-by: Tiago Lam <tiago.lam@intel.com>
> ---
>  drivers/net/af_packet/rte_eth_af_packet.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/drivers/net/af_packet/rte_eth_af_packet.c b/drivers/net/af_packet/rte_eth_af_packet.c
> index 95a98c6..264cfc0 100644
> --- a/drivers/net/af_packet/rte_eth_af_packet.c
> +++ b/drivers/net/af_packet/rte_eth_af_packet.c
> @@ -433,8 +433,7 @@ eth_dev_mtu_set(struct rte_eth_dev *dev, uint16_t mtu)
>  	int ret;
>  	int s;
>  	unsigned int data_size = internals->req.tp_frame_size -
> -				 TPACKET2_HDRLEN -
> -				 sizeof(struct sockaddr_ll);
> +				 TPACKET2_HDRLEN;
>  
>  	if (mtu > data_size)
>  		return -EINVAL;
> 

  parent reply	other threads:[~2018-11-20 10:29 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-11-20  9:54 [dpdk-dev] [PATCH " Tiago Lam
2018-11-20  9:54 ` [dpdk-dev] [PATCH 2/3] net/af_packet: Move parse and validation of iface Tiago Lam
2018-11-20  9:54 ` [dpdk-dev] [PATCH 3/3] net/af_packet: Get 'framesz' from the iface's MTU Tiago Lam
2018-11-20 10:26 ` [dpdk-dev] [PATCH v2 1/3] net/af_packet: set_mtu() decrements sockaddr twice Tiago Lam
2018-11-20 10:26   ` [dpdk-dev] [PATCH v2 2/3] net/af_packet: move parse and validation of iface Tiago Lam
2018-11-27 17:42     ` Ferruh Yigit
2018-11-20 10:26   ` [dpdk-dev] [PATCH v2 3/3] net/af_packet: get 'framesz' from the iface's MTU Tiago Lam
2018-11-27 17:43     ` Ferruh Yigit
2018-11-27 17:45       ` Ferruh Yigit
2018-11-28 13:12       ` Lam, Tiago
2018-11-28 13:33         ` Ferruh Yigit
2018-12-17  9:21           ` Lam, Tiago
2018-12-21 12:21             ` Ferruh Yigit
2019-02-18 18:01         ` Yigit, Ferruh
2019-03-19 13:16           ` Yigit, Ferruh
2019-03-19 13:16             ` Yigit, Ferruh
2018-11-20 10:29   ` Kevin Traynor [this message]
2018-11-20 10:45     ` [dpdk-dev] [PATCH v2 1/3] net/af_packet: set_mtu() decrements sockaddr twice Lam, Tiago
2018-11-27 17:42   ` Ferruh Yigit
2018-12-21 12:29   ` Ferruh Yigit

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