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Message-ID: <20240105104311.03a35622@device-28.home>
Date: Fri, 5 Jan 2024 10:43:11 +0100
From: Maxime Chevallier <maxime.chevallier@...tlin.com>
To: Jakub Kicinski <kuba@...nel.org>
Cc: davem@...emloft.net, netdev@...r.kernel.org,
linux-kernel@...r.kernel.org, thomas.petazzoni@...tlin.com, Andrew Lunn
<andrew@...n.ch>, Eric Dumazet <edumazet@...gle.com>, Paolo Abeni
<pabeni@...hat.com>, Russell King <linux@...linux.org.uk>,
linux-arm-kernel@...ts.infradead.org, Christophe Leroy
<christophe.leroy@...roup.eu>, Herve Codina <herve.codina@...tlin.com>,
Florian Fainelli <f.fainelli@...il.com>, Heiner Kallweit
<hkallweit1@...il.com>, Vladimir Oltean <vladimir.oltean@....com>,
Köry Maincent <kory.maincent@...tlin.com>, Jesse Brandeburg
<jesse.brandeburg@...el.com>, Jonathan Corbet <corbet@....net>, Marek
Behún <kabel@...nel.org>, Piergiorgio Beruto
<piergiorgio.beruto@...il.com>, Oleksij Rempel <o.rempel@...gutronix.de>,
Nicolò Veronese <nicveronese@...il.com>, Simon Horman
<horms@...nel.org>
Subject: Re: [PATCH net-next v5 07/13] net: ethtool: Introduce a command to
list PHYs on an interface
Hello Jakub,
Thanks a lot for the review on that part,
On Thu, 4 Jan 2024 15:34:01 -0800
Jakub Kicinski <kuba@...nel.org> wrote:
> On Thu, 21 Dec 2023 19:00:40 +0100 Maxime Chevallier wrote:
> > As we have the ability to track the PHYs connected to a net_device
> > through the link_topology, we can expose this list to userspace. This
> > allows userspace to use these identifiers for phy-specific commands and
> > take the decision of which PHY to target by knowing the link topology.
> >
> > Add PHY_GET and PHY_DUMP, which can be a filtered DUMP operation to list
> > devices on only one interface.
> >
> > Signed-off-by: Maxime Chevallier <maxime.chevallier@...tlin.com>
>
> > diff --git a/Documentation/networking/ethtool-netlink.rst b/Documentation/networking/ethtool-netlink.rst
> > index 3ca6c21e74af..97ff787a7dd8 100644
> > --- a/Documentation/networking/ethtool-netlink.rst
> > +++ b/Documentation/networking/ethtool-netlink.rst
> > @@ -2011,6 +2011,49 @@ The attributes are propagated to the driver through the following structure:
> > .. kernel-doc:: include/linux/ethtool.h
> > :identifiers: ethtool_mm_cfg
> >
> > +PHY_GET
> > +=======
> > +
> > +Retrieve information about a given Ethernet PHY sitting on the link. As there
> > +can be more than one PHY, the DUMP operation can be used to list the PHYs
> > +present on a given interface, by passing an interface index or name in
> > +the dump request
> > +
> > +Request contents:
> > +
> > + ==================================== ====== ==========================
> > + ``ETHTOOL_A_PHY_HEADER`` nested request header
> > + ==================================== ====== ==========================
> > +
> > +Kernel response contents:
> > +
> > + ===================================== ====== ==========================
> > + ``ETHTOOL_A_PHY_HEADER`` nested request header
> > + ``ETHTOOL_A_PHY_INDEX`` u32 the phy's unique index, that can
>
> The fact that lines are longer than the ===== markings doesn't generate
> warnings in htmldoc?
I did test the doc, but maybe I missed the warning. Since I'll need to
respin anyway, I'll clean this up :)
>
> > + be used for phy-specific requests
> > + ``ETHTOOL_A_PHY_DRVNAME`` string the phy driver name
> > + ``ETHTOOL_A_PHY_NAME`` string the phy device name
> > + ``ETHTOOL_A_PHY_UPSTREAM_TYPE`` u32 the type of device this phy is
> > + connected to
> > + ``ETHTOOL_A_PHY_UPSTREAM_PHY`` nested if the phy is connected to another
> > + phy, this nest contains info on
> > + that connection
> > + ``ETHTOOL_A_PHY_DOWNSTREAM_SFP_NAME`` string if the phy controls an sfp bus,
> > + the name of the sfp bus
>
> Is upstream / downstream clear to everyone / from the spec.
> I guess it's scoped to the netdev so upstream means "towards
> the netdev MAC"?
Good point, it's indeed scoped to the netdev, upstream means "towards
the MAC" and downstream "towards the link-partner". The upstream
terminology is used a little bit in the SFP code, but anyway should we
keep that terminology, I'll document it better both here and in the
dedicated documentation.
> > + ``ETHTOOL_A_PHY_ID`` u32 the phy id if the phy is C22
> > + ===================================== ====== ==========================
> > +
> > +When ``ETHTOOL_A_PHY_UPSTREAM_TYPE`` is PHY_UPSTREAM_PHY, the PHY's parent is
> > +another PHY. Information on the parent PHY will be set in the
> > +``ETHTOOL_A_PHY_UPSTREAM_PHY`` nest, which has the following structure :
> > +
> > + =================================== ====== ==========================
> > + ``ETHTOOL_A_PHY_UPSTREAM_INDEX`` u32 the PHY index of the upstream PHY
> > + ``ETHTOOL_A_PHY_UPSTREAM_SFP_NAME`` string if this PHY is connected to it's
> > + parent PHY through an SFP bus, the
> > + name of this sfp bus
> > + =================================== ====== ==========================
>
> Why is this a nest?
It was an attempt to structure the info, but I think we can do without,
as it only contains 2 fields.
> > Request translation
> > ===================
>
> > +enum {
> > + ETHTOOL_A_PHY_UNSPEC,
> > + ETHTOOL_A_PHY_HEADER, /* nest - _A_HEADER_* */
> > + ETHTOOL_A_PHY_INDEX, /* u32 */
> > + ETHTOOL_A_PHY_DRVNAME, /* string */
> > + ETHTOOL_A_PHY_NAME, /* string */
> > + ETHTOOL_A_PHY_UPSTREAM_TYPE, /* u8 */
>
> The Documentation say it's a u32 as it should be, AFAICT.
> But code and some comments use u8.
Ah my bad, Andrew did comment on that and I though I addressed the
inconsistency but there are some left apparently.
> > + ETHTOOL_A_PHY_UPSTREAM, /* nest - _A_PHY_UPSTREAM_* */
> > + ETHTOOL_A_PHY_DOWNSTREAM_SFP_NAME, /* string */
> > + ETHTOOL_A_PHY_ID, /* u32 */
> > +
> > + /* add new constants above here */
> > + __ETHTOOL_A_PHY_CNT,
> > + ETHTOOL_A_PHY_MAX = (__ETHTOOL_A_PHY_CNT - 1)
> > +};
>
> > +++ b/net/ethtool/phy.c
> > @@ -0,0 +1,306 @@
> > +// SPDX-License-Identifier: GPL-2.0-only
> > +/*
> > + * Copyright 2023 Bootlin
> > + *
> > + */
>
> Do you really need 4 lines for the copyright? :)
No I don't, I'll tidy this up :)
>
> > +/* Caller holds rtnl */
> > +static ssize_t
> > +ethnl_phy_reply_size(const struct ethnl_req_info *req_base,
> > + struct netlink_ext_ack *extack)
> > +{
> > + struct phy_link_topology *topo;
> > + struct phy_device_node *pdn;
> > + struct phy_device *phydev;
> > + unsigned long index;
> > + size_t size;
> > +
> > + ASSERT_RTNL();
> > +
> > + topo = &req_base->dev->link_topo;
> > +
> > + size = nla_total_size(0);
>
> no comment on this one?
Ah sorry I'll add it
> > +
> > + xa_for_each(&topo->phys, index, pdn) {
>
> Why count all the PHYs, you only output one on doit, right?
Uh ok good point, I'll fix it.
> > + phydev = pdn->phy;
> > +
> > + /* ETHTOOL_A_PHY_INDEX */
> > + size += nla_total_size(sizeof(u32));
> > +
> > + /* ETHTOOL_A_DRVNAME */
> > + size += nla_total_size(strlen(phydev->drv->name) + 1);
> > +
> > + /* ETHTOOL_A_NAME */
> > + size += nla_total_size(strlen(dev_name(&phydev->mdio.dev)) + 1);
> > +
> > + /* ETHTOOL_A_PHY_UPSTREAM_TYPE */
> > + size += nla_total_size(sizeof(u8));
> > +
> > + /* ETHTOOL_A_PHY_ID */
> > + size += nla_total_size(sizeof(u32));
> > +
> > + if (phy_on_sfp(phydev)) {
> > + const char *upstream_sfp_name = sfp_get_name(pdn->parent_sfp_bus);
> > +
> > + /* ETHTOOL_A_PHY_UPSTREAM_SFP_NAME */
> > + if (upstream_sfp_name)
> > + size += nla_total_size(strlen(upstream_sfp_name) + 1);
> > +
> > + /* ETHTOOL_A_PHY_UPSTREAM_INDEX */
> > + size += nla_total_size(sizeof(u32));
> > + }
> > +
> > + /* ETHTOOL_A_PHY_DOWNSTREAM_SFP_NAME */
> > + if (phydev->sfp_bus) {
> > + const char *sfp_name = sfp_get_name(phydev->sfp_bus);
> > +
> > + if (sfp_name)
> > + size += nla_total_size(strlen(sfp_name) + 1);
> > + }
> > + }
> > +
> > + return size;
> > +}
>
> > +static int ethnl_phy_parse_request(struct ethnl_req_info *req_base,
> > + struct nlattr **tb)
> > +{
> > + struct phy_link_topology *topo = &req_base->dev->link_topo;
> > + struct phy_req_info *req_info = PHY_REQINFO(req_base);
> > + struct phy_device_node *pdn;
> > +
> > + if (!req_base->phydev)
> > + return 0;
>
> The PHY INDEX should probably be a required attr, with
> GENL_REQ_ATTR_CHECK()? Without phydev being specified
> what's the point?
We can still have a phydev without passing a PHY INDEX, this would
report information on the netdev->phydev device, that can be helpful
for users to know which PHY is targeted by commands such as "ethtool
--cable-test eth0" when no PHY index is passed
> > + pdn = xa_load(&topo->phys, req_base->phydev->phyindex);
> > + memcpy(&req_info->pdn, pdn, sizeof(*pdn));
> > +
> > + return 0;
> > +}
>
> > +int ethnl_phy_dumpit(struct sk_buff *skb, struct netlink_callback *cb)
> > +{
> > + struct ethnl_phy_dump_ctx *ctx = (void *)cb->ctx;
> > + struct net *net = sock_net(skb->sk);
> > + unsigned long ifindex = 1;
>
> This doesn't look right, if dump gets full you gotta pick up
> when previous call left off.
I wasn't aware that this was the expected DUMP behaviour. So I should
keep track of the last dev and last phy_index dumped in the dump_ctx I
guess ? I'm not sure how I'm going to test this though, I only have
devices with at most 2 PHYs :(
> > + struct net_device *dev;
> > + int ret = 0;
> > +
> > + rtnl_lock();
> > +
> > + if (ctx->phy_req_info->base.dev) {
> > + ret = ethnl_phy_dump_one_dev(skb, ctx->phy_req_info->base.dev, cb);
> > + ethnl_parse_header_dev_put(&ctx->phy_req_info->base);
> > + ctx->phy_req_info->base.dev = NULL;
> > + } else {
> > + for_each_netdev_dump(net, dev, ifindex) {
> > + ret = ethnl_phy_dump_one_dev(skb, dev, cb);
> > + if (ret)
> > + break;
> > + }
> > + }
> > + rtnl_unlock();
> > +
> > + if (ret == -EMSGSIZE && skb->len)
> > + return skb->len;
> > + return ret;
> > +}
> > +
>
Thanks a lot for the review, the netlink part was definitely the hard
part for me.
Maxime
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