linux-kernel - RE: [PATCH v2 net-next 3/5] et: fec: add rx_frame

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID:
 <PAXPR04MB9185FC62D5928E5B265F41DC893EA@PAXPR04MB9185.eurprd04.prod.outlook.com>
Date: Mon, 25 Aug 2025 12:38:04 +0000
From: Shenwei Wang <shenwei.wang@....com>
To: Wei Fang <wei.fang@....com>
CC: Clark Wang <xiaoning.wang@....com>, Stanislav Fomichev <sdf@...ichev.me>,
	"imx@...ts.linux.dev" <imx@...ts.linux.dev>, "netdev@...r.kernel.org"
	<netdev@...r.kernel.org>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>, dl-linux-imx <linux-imx@....com>, Andrew Lunn
	<andrew+netdev@...n.ch>, "David S. Miller" <davem@...emloft.net>, Eric
 Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni
	<pabeni@...hat.com>, Alexei Starovoitov <ast@...nel.org>, Daniel Borkmann
	<daniel@...earbox.net>, Jesper Dangaard Brouer <hawk@...nel.org>, John
 Fastabend <john.fastabend@...il.com>
Subject: RE: [PATCH v2 net-next 3/5] et: fec: add rx_frame_size to support
 configurable RX length



> -----Original Message-----
> From: Wei Fang <wei.fang@....com>
> Sent: Sunday, August 24, 2025 9:26 PM
> To: Shenwei Wang <shenwei.wang@....com>
> Cc: Clark Wang <xiaoning.wang@....com>; Stanislav Fomichev
> <sdf@...ichev.me>; imx@...ts.linux.dev; netdev@...r.kernel.org; linux-
> kernel@...r.kernel.org; dl-linux-imx <linux-imx@....com>; Andrew Lunn
> <andrew+netdev@...n.ch>; David S. Miller <davem@...emloft.net>; Eric
> Dumazet <edumazet@...gle.com>; Jakub Kicinski <kuba@...nel.org>; Paolo
> Abeni <pabeni@...hat.com>; Alexei Starovoitov <ast@...nel.org>; Daniel
> Borkmann <daniel@...earbox.net>; Jesper Dangaard Brouer
> <hawk@...nel.org>; John Fastabend <john.fastabend@...il.com>
> Subject: RE: [PATCH v2 net-next 3/5] et: fec: add rx_frame_size to support
> configurable RX length
> 
> > > > @@ -4563,6 +4563,7 @@ fec_probe(struct platform_device *pdev)
> > > >  	pinctrl_pm_select_sleep_state(&pdev->dev);
> > > >
> > > >  	fep->pagepool_order = 0;
> > > > +	fep->rx_frame_size = FEC_ENET_RX_FRSIZE;
> > >
> > > According to the RM, to allow one maximum size frame per buffer,
> > > FEC_R_BUFF_SIZE must be set to FEC_R_CNTRL [MAX_FL] or larger.
> > > FEC_ENET_RX_FRSIZE is greater than PKT_MAXBUF_SIZE, I'm not sure
> > whether it
> > > will cause some unknown issues.
> >
> > MAX_FL defines the maximum allowable frame length, while TRUNC_FL
> > specifies the threshold beyond which frames are truncated. Based on
> > this logic, the documentation appears to be incorrect-TRUNC_FL should
> > never exceed MAX_FL, as doing so would make the truncation mechanism
> > ineffective.
> >
> > This has been confirmed through testing data.
> >
> 
> One obvious issue I can see is that the Rx error statistic would be doubled the
> actual number when the FEC receives jumbo frames.
> 
> For example, the sender sends 1000 jumbo frames (8000 bytes) to the FEC port,
> without this patch set, the Rx error statistic of FEC should be 1000, however, after
> applying this patch set (rx_frame_size is 3520, max_buf_size is 1984), I can see
> the Rx error statistic is 2000.

I don't think there is a case that rx_frame_size is 3520 while the max_buf_size is 1984.
With the patch, the rx_frame_size should always less than the max_buf_size. Otherwise,
the implementation might have a logic bug.

Regards,
Shenwei