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Subject: Re: [PATCH v3 2/2] net-sysfs: Ensure begin/complete are called in
 speed_show() and duplex_show()
From:   Kai-Heng Feng <kai.heng.feng@canonical.com>
In-Reply-To: <425AF2D4-1FEE-437B-8520-452F818F7DEE@canonical.com>
Date:   Wed, 11 Mar 2020 11:30:49 +0800
Cc:     Jakub Kicinski <kuba@kernel.org>,
        Maxime Chevallier <maxime.chevallier@bootlin.com>,
        Heiner Kallweit <hkallweit1@gmail.com>,
        Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
        Jouni Hogander <jouni.hogander@unikie.com>,
        Eric Dumazet <edumazet@google.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Wang Hai <wanghai26@huawei.com>,
        YueHaibing <yuehaibing@huawei.com>,
        Kimberly Brown <kimbrownkd@gmail.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Florian Fainelli <f.fainelli@gmail.com>,
        Jiri Pirko <jiri@mellanox.com>, Andrew Lunn <andrew@lunn.ch>,
        Li RongQing <lirongqing@baidu.com>,
        open list <linux-kernel@vger.kernel.org>,
        "open list:NETWORKING [GENERAL]" <netdev@vger.kernel.org>
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Message-Id: <BEFADD90-2EC7-4B46-8AF4-F1D1CCD81993@canonical.com>
References: <20200207101005.4454-1-kai.heng.feng@canonical.com>
 <20200207101005.4454-2-kai.heng.feng@canonical.com>
 <425AF2D4-1FEE-437B-8520-452F818F7DEE@canonical.com>
To:     David Miller <davem@davemloft.net>,
        Michal Kubecek <mkubecek@suse.cz>,
        Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Sender: linux-kernel-owner@vger.kernel.org
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> On Feb 20, 2020, at 13:45, Kai-Heng Feng <kai.heng.feng@canonical.com> wrote:
> 
>> 
>> On Feb 7, 2020, at 18:10, Kai-Heng Feng <kai.heng.feng@canonical.com> wrote:
>> 
>> Device like igb gets runtime suspended when there's no link partner. We
>> can't get correct speed under that state:
>> $ cat /sys/class/net/enp3s0/speed
>> 1000
>> 
>> In addition to that, an error can also be spotted in dmesg:
>> [  385.991957] igb 0000:03:00.0 enp3s0: PCIe link lost
>> 
>> It's because the igb device doesn't get runtime resumed before calling
>> get_link_ksettings().
>> 
>> So let's use a new helper to call begin() and complete() like what
>> dev_ethtool() does, to runtime resume/suspend or power up/down the
>> device properly.
>> 
>> Once this fix is in place, igb can show the speed correctly without link
>> partner:
>> $ cat /sys/class/net/enp3s0/speed
>> -1
>> 
>> -1 here means SPEED_UNKNOWN, which is the correct value when igb is
>> runtime suspended.
>> 
>> Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
> 
> A gentle ping...

Another gentle ping...

> 
> Kai-Heng
> 
>> ---
>> v3:
>> - Specify -1 means SPEED_UNKNOWN.
>> v2:
>> - Add a new helper with begin/complete and use it in net-sysfs.
>> 
>> include/linux/ethtool.h |  4 ++++
>> net/core/net-sysfs.c    |  4 ++--
>> net/ethtool/ioctl.c     | 33 ++++++++++++++++++++++++++++++++-
>> 3 files changed, 38 insertions(+), 3 deletions(-)
>> 
>> diff --git a/include/linux/ethtool.h b/include/linux/ethtool.h
>> index 95991e4300bf..785ec1921417 100644
>> --- a/include/linux/ethtool.h
>> +++ b/include/linux/ethtool.h
>> @@ -160,6 +160,10 @@ extern int
>> __ethtool_get_link_ksettings(struct net_device *dev,
>> 			     struct ethtool_link_ksettings *link_ksettings);
>> 
>> +extern int
>> +__ethtool_get_link_ksettings_full(struct net_device *dev,
>> +				  struct ethtool_link_ksettings *link_ksettings);
>> +
>> /**
>> * ethtool_intersect_link_masks - Given two link masks, AND them together
>> * @dst: first mask and where result is stored
>> diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
>> index 4c826b8bf9b1..a199e15a080f 100644
>> --- a/net/core/net-sysfs.c
>> +++ b/net/core/net-sysfs.c
>> @@ -201,7 +201,7 @@ static ssize_t speed_show(struct device *dev,
>> 	if (netif_running(netdev)) {
>> 		struct ethtool_link_ksettings cmd;
>> 
>> -		if (!__ethtool_get_link_ksettings(netdev, &cmd))
>> +		if (!__ethtool_get_link_ksettings_full(netdev, &cmd))
>> 			ret = sprintf(buf, fmt_dec, cmd.base.speed);
>> 	}
>> 	rtnl_unlock();
>> @@ -221,7 +221,7 @@ static ssize_t duplex_show(struct device *dev,
>> 	if (netif_running(netdev)) {
>> 		struct ethtool_link_ksettings cmd;
>> 
>> -		if (!__ethtool_get_link_ksettings(netdev, &cmd)) {
>> +		if (!__ethtool_get_link_ksettings_full(netdev, &cmd)) {
>> 			const char *duplex;
>> 
>> 			switch (cmd.base.duplex) {
>> diff --git a/net/ethtool/ioctl.c b/net/ethtool/ioctl.c
>> index b987052d91ef..faeba247c1fb 100644
>> --- a/net/ethtool/ioctl.c
>> +++ b/net/ethtool/ioctl.c
>> @@ -420,7 +420,9 @@ struct ethtool_link_usettings {
>> 	} link_modes;
>> };
>> 
>> -/* Internal kernel helper to query a device ethtool_link_settings. */
>> +/* Internal kernel helper to query a device ethtool_link_settings. To be called
>> + * inside begin/complete block.
>> + */
>> int __ethtool_get_link_ksettings(struct net_device *dev,
>> 				 struct ethtool_link_ksettings *link_ksettings)
>> {
>> @@ -434,6 +436,35 @@ int __ethtool_get_link_ksettings(struct net_device *dev,
>> }
>> EXPORT_SYMBOL(__ethtool_get_link_ksettings);
>> 
>> +/* Internal kernel helper to query a device ethtool_link_settings. To be called
>> + * outside of begin/complete block.
>> + */
>> +int __ethtool_get_link_ksettings_full(struct net_device *dev,
>> +				      struct ethtool_link_ksettings *link_ksettings)
>> +{
>> +	int rc;
>> +
>> +	ASSERT_RTNL();
>> +
>> +	if (!dev->ethtool_ops->get_link_ksettings)
>> +		return -EOPNOTSUPP;
>> +
>> +	if (dev->ethtool_ops->begin) {
>> +		rc = dev->ethtool_ops->begin(dev);
>> +		if (rc  < 0)
>> +			return rc;
>> +	}
>> +
>> +	memset(link_ksettings, 0, sizeof(*link_ksettings));
>> +	rc = dev->ethtool_ops->get_link_ksettings(dev, link_ksettings);
>> +
>> +	if (dev->ethtool_ops->complete)
>> +		dev->ethtool_ops->complete(dev);
>> +
>> +	return rc;
>> +}
>> +EXPORT_SYMBOL(__ethtool_get_link_ksettings_full);
>> +
>> /* convert ethtool_link_usettings in user space to a kernel internal
>> * ethtool_link_ksettings. return 0 on success, errno on error.
>> */
>> -- 
>> 2.17.1