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From: Russell King - ARM Linux admin <linux@armlinux.org.uk>
To: Grygorii Strashko <grygorii.strashko@ti.com>
Cc: Kurt Kanzenbach <kurt@linutronix.de>,
	Petr Machata <petrm@mellanox.com>,
	Richard Cochran <richardcochran@gmail.com>,
	Andrew Lunn <andrew@lunn.ch>,
	Vivien Didelot <vivien.didelot@gmail.com>,
	Florian Fainelli <f.fainelli@gmail.com>,
	"David S. Miller" <davem@davemloft.net>,
	Jakub Kicinski <kuba@kernel.org>, Jiri Pirko <jiri@mellanox.com>,
	Ido Schimmel <idosch@mellanox.com>,
	Heiner Kallweit <hkallweit1@gmail.com>,
	Ivan Khoronzhuk <ivan.khoronzhuk@linaro.org>,
	Samuel Zou <zou_wei@huawei.com>,
	netdev@vger.kernel.org
Subject: Re: [PATCH v3 1/9] ptp: Add generic ptp v2 header parsing function
Date: Tue, 4 Aug 2020 22:44:48 +0100
Message-ID: <20200804214448.GV1551@shell.armlinux.org.uk> (raw)
In-Reply-To: <45130ed9-7429-f1cd-653b-64417d5a93aa@ti.com>

On Wed, Aug 05, 2020 at 12:34:47AM +0300, Grygorii Strashko wrote:
> On 05/08/2020 00:07, Russell King - ARM Linux admin wrote:
> > On Tue, Aug 04, 2020 at 11:56:12PM +0300, Grygorii Strashko wrote:
> > > 
> > > 
> > > On 31/07/2020 13:06, Kurt Kanzenbach wrote:
> > > > On Thu Jul 30 2020, Petr Machata wrote:
> > > > > Kurt Kanzenbach <kurt@linutronix.de> writes:
> > > > > 
> > > > > > @@ -107,6 +107,37 @@ unsigned int ptp_classify_raw(const struct sk_buff *skb)
> > > > > >    }
> > > > > >    EXPORT_SYMBOL_GPL(ptp_classify_raw);
> > > > > > +struct ptp_header *ptp_parse_header(struct sk_buff *skb, unsigned int type)
> > > > > > +{
> > > > > > +	u8 *data = skb_mac_header(skb);
> > > > > > +	u8 *ptr = data;
> > > > > 
> > > > > One of the "data" and "ptr" variables is superfluous.
> > > > 
> > > > Yeah. Can be shortened to u8 *ptr = skb_mac_header(skb);
> > > 
> > > Actually usage of skb_mac_header(skb) breaks CPTS RX time-stamping on
> > > am571x platform PATCH 6.
> > > 
> > > The CPSW RX timestamp requested after full packet put in SKB, but
> > > before calling eth_type_trans().
> > > 
> > > So, skb->data pints on Eth header, but skb_mac_header() return garbage.
> > > 
> > > Below diff fixes it for me.
> > 
> > However, that's likely to break everyone else.
> > 
> > For example, anyone calling this from the mii_timestamper rxtstamp()
> > method, the skb will have been classified with the MAC header pushed
> > and restored, so skb->data points at the network header.
> > 
> > Your change means that ptp_parse_header() expects the MAC header to
> > also be pushed.
> > 
> > Is it possible to adjust CPTS?
> > 
> > Looking at:
> > drivers/net/ethernet/ti/cpsw.c... yes.
> > drivers/net/ethernet/ti/cpsw_new.c... yes.
> > drivers/net/ethernet/ti/netcp_core.c... unclear.
> > 
> > If not, maybe cpts should remain unconverted - I don't see any reason
> > to provide a generic function for one user.
> > 
> 
> Could it be an option to pass "u8 *ptr" instead of "const struct sk_buff *skb" as
> input parameter to ptp_parse_header()?

It needs to read from the buffer, and in order to do that, it needs to
validate that the buffer contains sufficient data.  So, at minimum it
needs to be a pointer and size of valid data.

I was thinking about suggesting that as a core function, with a wrapper
for the existing interface.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!

  reply index

Thread overview: 44+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-30  8:00 [PATCH v3 0/9] ptp: Add generic helper functions Kurt Kanzenbach
2020-07-30  8:00 ` [PATCH v3 1/9] ptp: Add generic ptp v2 header parsing function Kurt Kanzenbach
2020-07-30 10:15   ` Petr Machata
2020-07-31 10:06     ` Kurt Kanzenbach
2020-08-04 20:56       ` Grygorii Strashko
2020-08-04 21:07         ` Russell King - ARM Linux admin
2020-08-04 21:34           ` Grygorii Strashko
2020-08-04 21:44             ` Russell King - ARM Linux admin [this message]
2020-08-04 22:04               ` Grygorii Strashko
2020-08-04 23:14                 ` Russell King - ARM Linux admin
2020-08-05  9:29                   ` Kurt Kanzenbach
2020-08-05 12:59                     ` Grygorii Strashko
2020-08-05 13:57                       ` Kurt Kanzenbach
2020-08-05 19:15                         ` Grygorii Strashko
2020-08-06  7:56                           ` Kurt Kanzenbach
2020-08-05 15:25         ` Richard Cochran
2020-08-02 15:13   ` Richard Cochran
2020-08-02 20:20   ` Florian Fainelli
2020-07-30  8:00 ` [PATCH v3 2/9] ptp: Add generic ptp message type function Kurt Kanzenbach
2020-08-02 15:18   ` Richard Cochran
2020-08-02 20:20   ` Florian Fainelli
2020-07-30  8:00 ` [PATCH v3 3/9] net: dsa: mv88e6xxx: Use generic helper function Kurt Kanzenbach
2020-08-02 15:18   ` Richard Cochran
2020-08-02 20:21   ` Florian Fainelli
2020-07-30  8:00 ` [PATCH v3 4/9] mlxsw: spectrum_ptp: " Kurt Kanzenbach
2020-07-30 10:20   ` Petr Machata
2020-08-02 20:21   ` Florian Fainelli
2020-07-30  8:00 ` [PATCH v3 5/9] ethernet: ti: am65-cpts: " Kurt Kanzenbach
2020-07-30  9:19   ` Grygorii Strashko
2020-07-30  9:36     ` Kurt Kanzenbach
2020-07-30 10:24       ` Arnd Bergmann
2020-07-31 11:48         ` Kurt Kanzenbach
2020-07-31 12:55           ` Grygorii Strashko
2020-07-31 13:10             ` Kurt Kanzenbach
2020-07-30  8:00 ` [PATCH v3 6/9] ethernet: ti: cpts: " Kurt Kanzenbach
2020-08-02 20:22   ` Florian Fainelli
2020-08-05 18:52     ` Grygorii Strashko
2020-07-30  8:00 ` [PATCH v3 7/9] net: phy: dp83640: " Kurt Kanzenbach
2020-08-02 20:23   ` Florian Fainelli
2020-08-02 22:54   ` Richard Cochran
2020-07-30  8:00 ` [PATCH v3 8/9] ptp: ptp_ines: " Kurt Kanzenbach
2020-08-02 20:23   ` Florian Fainelli
2020-07-30  8:00 ` [PATCH v3 9/9] ptp: Remove unused macro Kurt Kanzenbach
2020-08-02 20:24   ` Florian Fainelli

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