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Date: Tue, 5 May 2020 12:42:26 +0200
From: Michal Kubecek <mkubecek@...e.cz>
To: Andrew Lunn <andrew@...n.ch>
Cc: David Miller <davem@...emloft.net>,
netdev <netdev@...r.kernel.org>,
Florian Fainelli <f.fainelli@...il.com>,
Heiner Kallweit <hkallweit1@...il.com>,
Chris Healy <cphealy@...il.com>, michael@...le.cc
Subject: Re: [PATCH net-next v2 06/10] net: ethtool: Add infrastructure for
reporting cable test results
On Tue, May 05, 2020 at 02:18:17AM +0200, Andrew Lunn wrote:
> Provide infrastructure for PHY drivers to report the cable test
> results. A netlink skb is associated to the phydev. Helpers will be
> added which can add results to this skb. Once the test has finished
> the results are sent to user space.
>
> When netlink ethtool is not part of the kernel configuration stubs are
> provided. It is also impossible to trigger a cable test, so the error
> code returned by the alloc function is of no consequence.
>
> v2:
> Include the status complete in the netlink notification message
>
> Signed-off-by: Andrew Lunn <andrew@...n.ch>
> ---
> drivers/net/phy/phy.c | 22 +++++++++++--
> include/linux/ethtool_netlink.h | 20 ++++++++++++
> include/linux/phy.h | 5 +++
> net/ethtool/cabletest.c | 55 +++++++++++++++++++++++++++++++++
> 4 files changed, 100 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/net/phy/phy.c b/drivers/net/phy/phy.c
> index cea89785bcd4..039e41e15c7e 100644
> --- a/drivers/net/phy/phy.c
> +++ b/drivers/net/phy/phy.c
> @@ -22,6 +22,7 @@
> #include <linux/module.h>
> #include <linux/mii.h>
> #include <linux/ethtool.h>
> +#include <linux/ethtool_netlink.h>
> #include <linux/phy.h>
> #include <linux/phy_led_triggers.h>
> #include <linux/sfp.h>
> @@ -30,6 +31,9 @@
> #include <linux/io.h>
> #include <linux/uaccess.h>
> #include <linux/atomic.h>
> +#include <net/netlink.h>
> +#include <net/genetlink.h>
> +#include <net/sock.h>
>
> #define PHY_STATE_TIME HZ
>
> @@ -476,6 +480,8 @@ static void phy_abort_cable_test(struct phy_device *phydev)
> {
> int err;
>
> + ethnl_cable_test_finished(phydev);
> +
> err = phy_init_hw(phydev);
> if (err)
> phydev_err(phydev, "Error while aborting cable test");
> @@ -484,7 +490,7 @@ static void phy_abort_cable_test(struct phy_device *phydev)
> int phy_start_cable_test(struct phy_device *phydev,
> struct netlink_ext_ack *extack)
> {
> - int err;
> + int err = -ENOMEM;
>
> if (!(phydev->drv &&
> phydev->drv->cable_test_start &&
> @@ -510,19 +516,30 @@ int phy_start_cable_test(struct phy_device *phydev,
> goto out;
> }
>
> + err = ethnl_cable_test_alloc(phydev);
> + if (err)
> + goto out;
> +
> /* Mark the carrier down until the test is complete */
> phy_link_down(phydev, true);
>
> err = phydev->drv->cable_test_start(phydev);
> if (err) {
> phy_link_up(phydev);
> - goto out;
> + goto out_free;
> }
>
> phydev->state = PHY_CABLETEST;
>
> if (phy_polling_mode(phydev))
> phy_trigger_machine(phydev);
> +
> + mutex_unlock(&phydev->lock);
> +
> + return 0;
> +
> +out_free:
> + ethnl_cable_test_free(phydev);
> out:
> mutex_unlock(&phydev->lock);
>
> @@ -962,6 +979,7 @@ void phy_state_machine(struct work_struct *work)
> }
>
> if (finished) {
> + ethnl_cable_test_finished(phydev);
> needs_aneg = true;
> phydev->state = PHY_UP;
> }
> diff --git a/include/linux/ethtool_netlink.h b/include/linux/ethtool_netlink.h
> index d01b77887f82..7d763ba22f6f 100644
> --- a/include/linux/ethtool_netlink.h
> +++ b/include/linux/ethtool_netlink.h
> @@ -14,4 +14,24 @@ enum ethtool_multicast_groups {
> ETHNL_MCGRP_MONITOR,
> };
>
> +struct phy_device;
> +
> +#if IS_ENABLED(CONFIG_ETHTOOL_NETLINK)
> +int ethnl_cable_test_alloc(struct phy_device *phydev);
> +void ethnl_cable_test_free(struct phy_device *phydev);
> +void ethnl_cable_test_finished(struct phy_device *phydev);
> +#else
> +static inline int ethnl_cable_test_alloc(struct phy_device *phydev)
> +{
> + return -ENOTSUPP;
> +}
> +
> +static inline void ethnl_cable_test_free(struct phy_device *phydev)
> +{
> +}
> +
> +static inline void ethnl_cable_test_finished(struct phy_device *phydev)
> +{
> +}
> +#endif /* IS_ENABLED(ETHTOOL_NETLINK) */
> #endif /* _LINUX_ETHTOOL_NETLINK_H_ */
> diff --git a/include/linux/phy.h b/include/linux/phy.h
> index 593da2c6041d..ee69f781995a 100644
> --- a/include/linux/phy.h
> +++ b/include/linux/phy.h
> @@ -487,6 +487,11 @@ struct phy_device {
> /* For use by PHYs to maintain extra state */
> void *priv;
>
> + /* Reporting cable test results */
> + struct sk_buff *skb;
> + void *ehdr;
> + struct nlattr *nest;
> +
> /* Interrupt and Polling infrastructure */
> struct delayed_work state_queue;
>
> diff --git a/net/ethtool/cabletest.c b/net/ethtool/cabletest.c
> index 6e5782a7da80..4c888db33ef0 100644
> --- a/net/ethtool/cabletest.c
> +++ b/net/ethtool/cabletest.c
> @@ -1,6 +1,7 @@
> // SPDX-License-Identifier: GPL-2.0-only
>
> #include <linux/phy.h>
> +#include <linux/ethtool_netlink.h>
> #include "netlink.h"
> #include "common.h"
> #include "bitset.h"
> @@ -59,3 +60,57 @@ int ethnl_act_cable_test(struct sk_buff *skb, struct genl_info *info)
> dev_put(dev);
> return ret;
> }
> +
> +int ethnl_cable_test_alloc(struct phy_device *phydev)
> +{
> + int err = -ENOMEM;
> +
> + phydev->skb = genlmsg_new(NLMSG_GOODSIZE, GFP_KERNEL);
> + if (!phydev->skb)
> + goto out;
> +
> + phydev->ehdr = ethnl_bcastmsg_put(phydev->skb,
> + ETHTOOL_MSG_CABLE_TEST_NTF);
> + if (!phydev->ehdr) {
> + err = -EINVAL;
This should be -EMSGSIZE.
> + goto out;
> + }
> +
> + err = ethnl_fill_reply_header(phydev->skb, phydev->attached_dev,
> + ETHTOOL_A_CABLE_TEST_NTF_HEADER);
> + if (err)
> + goto out;
> +
> + err = nla_put_u8(phydev->skb, ETHTOOL_A_CABLE_TEST_NTF_STATUS,
> + ETHTOOL_A_CABLE_TEST_NTF_STATUS_COMPLETED);
> + if (err)
> + goto out;
> +
> + phydev->nest = nla_nest_start(phydev->skb,
> + ETHTOOL_A_CABLE_TEST_NTF_NEST);
> + if (!phydev->nest)
> + goto out;
If nla_nest_start() fails, we still have 0 in err.
> +
> + return 0;
> +
> +out:
> + nlmsg_free(phydev->skb);
> + return err;
> +}
> +EXPORT_SYMBOL_GPL(ethnl_cable_test_alloc);
Do you think it would make sense to set phydev->skb to NULL on failure
and also in ethnl_cable_test_free() and ethnl_cable_test_finished() so
that if driver messes up, it hits null pointer dereference which is much
easier to debug than use after free?
Michal
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