From: Steen Hegelund <steen.hegelund@microchip.com>
To: Andrew Lunn <andrew@lunn.ch>
Cc: "David S. Miller" <davem@davemloft.net>,
Jakub Kicinski <kuba@kernel.org>,
Masahiro Yamada <masahiroy@kernel.org>,
Lars Povlsen <lars.povlsen@microchip.com>,
Bjarni Jonasson <bjarni.jonasson@microchip.com>,
Microchip Linux Driver Support <UNGLinuxDriver@microchip.com>,
Alexandre Belloni <alexandre.belloni@bootlin.com>,
Microsemi List <microsemi@lists.bootlin.com>,
<netdev@vger.kernel.org>, <linux-kernel@vger.kernel.org>
Subject: Re: [RFC PATCH 2/3] net: sparx5: Add Sparx5 switchdev driver
Date: Mon, 30 Nov 2020 14:17:48 +0100 [thread overview]
Message-ID: <20201130131748.oqrzjhyf543gj3jo@mchp-dev-shegelun> (raw)
In-Reply-To: <20201128184514.GD2191767@lunn.ch>
On 28.11.2020 19:45, Andrew Lunn wrote:
>EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
>
>> +/* Add a potentially wrapping 32 bit value to a 64 bit counter */
>> +static inline void sparx5_update_counter(u64 *cnt, u32 val)
>> +{
>> + if (val < (*cnt & U32_MAX))
>> + *cnt += (u64)1 << 32; /* value has wrapped */
>> +
>> + *cnt = (*cnt & ~(u64)U32_MAX) + val;
>> +}
>
>I don't follow what this is doing. Could you give some examples?
The statistics counters comes from different sources, and unfortunately
have different layouts: Some are 32 bit and some a 40 bit, so this
function is a wrapper to be able to handle them in the same way, polling
the counters often enough to be able to catch overruns.
>
>> +static const char *const sparx5_stats_layout[] = {
>> + "rx_in_bytes",
>> + "rx_symbol_err",
>> + "rx_pause",
>> + "rx_unsup_opcode",
>
>> +static void sparx5_update_port_stats(struct sparx5 *sparx5, int portno)
>> +{
>> + struct sparx5_port *spx5_port = sparx5->ports[portno];
>> + bool high_speed_dev = sparx5_is_high_speed_device(&spx5_port->conf);
>
>Reverse christmas tree. Which in this case, means you need to move the
>assignment into the body of the code.
OK.
>
>> +static void sparx5_get_sset_strings(struct net_device *ndev, u32 sset, u8 *data)
>> +{
>> + struct sparx5_port *port = netdev_priv(ndev);
>> + struct sparx5 *sparx5 = port->sparx5;
>> + int idx;
>> +
>> + if (sset != ETH_SS_STATS)
>> + return;
>> +
>> + for (idx = 0; idx < sparx5->num_stats; idx++)
>> + memcpy(data + idx * ETH_GSTRING_LEN,
>> + sparx5->stats_layout[idx], ETH_GSTRING_LEN);
>
>You cannot use memcpy here, because the strings you have defined are
>not ETH_GSTRING_LEN long. We once had a driver which happened to have
>its strings at the end of a page. The memcpy would copy the string,
>but keep going passed the end of string, over the page boundary, and
>trigger a segmentation fault.
Yes, I see that.
Thanks for the comments
/Steen
>
> Andrew
BR
Steen
---------------------------------------
Steen Hegelund
steen.hegelund@microchip.com
next prev parent reply other threads:[~2020-11-30 13:19 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-27 13:33 [RFC PATCH 0/3] net: Adding the Sparx5 Switch Driver Steen Hegelund
2020-11-27 13:33 ` [RFC PATCH 1/3] dt-bindings: net: sparx5: Add sparx5-switch bindings Steen Hegelund
2020-11-27 17:00 ` Andrew Lunn
2020-11-30 13:09 ` Steen Hegelund
2020-11-30 14:05 ` Andrew Lunn
2020-11-30 15:33 ` Steen Hegelund
2020-11-27 13:33 ` [RFC PATCH 2/3] net: sparx5: Add Sparx5 switchdev driver Steen Hegelund
2020-11-27 17:15 ` Andrew Lunn
2020-11-30 13:13 ` Steen Hegelund
2020-12-07 13:33 ` Jiri Pirko
2020-11-28 18:45 ` Andrew Lunn
2020-11-30 13:17 ` Steen Hegelund [this message]
2020-11-28 19:03 ` Andrew Lunn
2020-11-30 13:28 ` Steen Hegelund
2020-11-30 15:34 ` Andrew Lunn
2020-11-28 19:06 ` Andrew Lunn
2020-11-28 19:37 ` Russell King - ARM Linux admin
2020-11-28 20:07 ` Alexandre Belloni
2020-11-28 20:21 ` Andrew Lunn
2020-11-28 22:28 ` Russell King - ARM Linux admin
2020-11-29 10:52 ` Russell King - ARM Linux admin
2020-11-29 11:28 ` Russell King - ARM Linux admin
2020-11-30 14:39 ` Steen Hegelund
2020-11-30 14:54 ` Russell King - ARM Linux admin
2020-11-29 11:30 ` Russell King - ARM Linux admin
2020-11-30 14:30 ` Steen Hegelund
2020-11-30 14:50 ` Russell King - ARM Linux admin
2020-11-30 14:15 ` Steen Hegelund
2020-11-30 14:52 ` Russell King - ARM Linux admin
2020-11-30 14:10 ` Steen Hegelund
2020-11-28 19:24 ` Andrew Lunn
2020-12-01 11:11 ` Lars Povlsen
2020-11-29 17:16 ` Andrew Lunn
2020-11-30 13:33 ` Steen Hegelund
2020-11-29 17:26 ` Andrew Lunn
2020-11-30 13:31 ` Steen Hegelund
2020-11-29 17:35 ` Andrew Lunn
2020-11-30 14:42 ` Steen Hegelund
2020-11-27 13:33 ` [RFC PATCH 3/3] arm64: dts: sparx5: Add the Sparx5 switch node Steen Hegelund
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