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Date:   Wed, 5 Jan 2022 16:57:35 +0100
From:   Henning Schild <henning.schild@siemens.com>
To:     Aaron Ma <aaron.ma@canonical.com>
CC:     <kuba@kernel.org>, <linux-usb@vger.kernel.org>,
        <netdev@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
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Subject: Re: [PATCH 1/3 v3] net: usb: r8152: Check used MAC passthrough
 address
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Ok this now will claim only the first plugged in dongle. Probably as
you wanted it. But still breaking my always two ethernet cables and no
"lenovo dock" anywhere.

Still feels very wrong to me, but i have no clue how it is supposed to
work. Lenovo documentation talks about PXE use-cases ... which means
BIOS is spoofing and not OS. OS should probably just take the active
MAC instead of the one from EEPROM.
But it also has a link to one "dock" that is really just a dongle. And
the whole thing is super dated.

https://support.lenovo.com/ie/en/solutions/ht503574

Henning

Am Wed,  5 Jan 2022 23:14:25 +0800
schrieb Aaron Ma <aaron.ma@canonical.com>:

> When plugin multiple r8152 ethernet dongles to Lenovo Docks
> or USB hub, MAC passthrough address from BIOS should be
> checked if it had been used to avoid using on other dongles.
> 
> Currently builtin r8152 on Dock still can't be identified.
> First detected r8152 will use the MAC passthrough address.
> 
> v2:
> Skip builtin PCI MAC address which is share MAC address with
> passthrough MAC.
> Check thunderbolt based ethernet.
> 
> v3:
> Add return value.
> 
> Fixes: f77b83b5bbab ("net: usb: r8152: Add MAC passthrough support for
> more Lenovo Docks")
> Signed-off-by: Aaron Ma <aaron.ma@canonical.com>
> ---
>  drivers/net/usb/r8152.c | 15 +++++++++++++++
>  1 file changed, 15 insertions(+)
> 
> diff --git a/drivers/net/usb/r8152.c b/drivers/net/usb/r8152.c
> index f9877a3e83ac..2483dc421dff 100644
> --- a/drivers/net/usb/r8152.c
> +++ b/drivers/net/usb/r8152.c
> @@ -25,6 +25,7 @@
>  #include <linux/atomic.h>
>  #include <linux/acpi.h>
>  #include <linux/firmware.h>
> +#include <linux/pci.h>
>  #include <crypto/hash.h>
>  #include <linux/usb/r8152.h>
>  
> @@ -1605,6 +1606,7 @@ static int vendor_mac_passthru_addr_read(struct
> r8152 *tp, struct sockaddr *sa) char *mac_obj_name;
>  	acpi_object_type mac_obj_type;
>  	int mac_strlen;
> +	struct net_device *ndev;
>  
>  	if (tp->lenovo_macpassthru) {
>  		mac_obj_name = "\\MACA";
> @@ -1662,6 +1664,19 @@ static int
> vendor_mac_passthru_addr_read(struct r8152 *tp, struct sockaddr *sa)
> ret = -EINVAL; goto amacout;
>  	}
> +	rcu_read_lock();
> +	for_each_netdev_rcu(&init_net, ndev) {
> +		if (ndev->dev.parent && dev_is_pci(ndev->dev.parent)
> &&
> +
> !pci_is_thunderbolt_attached(to_pci_dev(ndev->dev.parent)))
> +			continue;
> +		if (strncmp(buf, ndev->dev_addr, 6) == 0) {
> +			ret = -EINVAL;
> +			rcu_read_unlock();
> +			goto amacout;
> +		}
> +	}
> +	rcu_read_unlock();
> +
>  	memcpy(sa->sa_data, buf, 6);
>  	netif_info(tp, probe, tp->netdev,
>  		   "Using pass-thru MAC addr %pM\n", sa->sa_data);