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SubjectRe: [PATCH 2/2] ethtool: Call begin() and complete() in __ethtool_get_link_ksettings()
On Fri, Jan 10, 2020 at 03:41:59PM +0800, Kai-Heng Feng 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 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

I agree that we definitely should make sure ->begin() and ->complete()
are always called around ethtool_ops calls. But even if nesting should
be safe now (for in-tree drivers, that is), I'm not really happy about
calling them even in places where we positively know we are always
inside a begin / complete block as e.g. vxlan or net_failover do. (And
also linkinfo.c and linkmodes.c but it may be easier to call
->get_link_ksettings() directly there.)

How about having two helpers: one simple for "ethtool context" where we
know we already are between ->begin() and ->complete() and one with the
begin/complete calls for the rest? Another interesting question is if
any of the callers which do not have their own begin()/complete() wrap
does actually need anything more than speed and duplex (I didn't do
a full check).

Michal

> Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
> ---
> net/ethtool/ioctl.c | 15 ++++++++++++++-
> 1 file changed, 14 insertions(+), 1 deletion(-)
>
> diff --git a/net/ethtool/ioctl.c b/net/ethtool/ioctl.c
> index 182bffbffa78..c768dbf45fc4 100644
> --- a/net/ethtool/ioctl.c
> +++ b/net/ethtool/ioctl.c
> @@ -423,13 +423,26 @@ struct ethtool_link_usettings {
> int __ethtool_get_link_ksettings(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));
> - return dev->ethtool_ops->get_link_ksettings(dev, 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);
>
> --
> 2.17.1
>

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