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Date:   Wed, 5 Jan 2022 15:48:57 +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>,
        <davem@davemloft.net>, <hayeswang@realtek.com>, <tiwai@suse.de>
Subject: Re: [PATCH 1/3] net: usb: r8152: Check used MAC passthrough address
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No cover letter?

I think p1 and 2 should be squashed.

Am Wed,  5 Jan 2022 22:23:49 +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.
> 
> Skip builtin PCI MAC address which is share MAC address with
> passthrough MAC.
> Check thunderbolt based ethernet.
> 
> Currently builtin r8152 on Dock still can't be identified.
> First detected r8152 will use the MAC passthrough address.
> 
> Signed-off-by: Aaron Ma <aaron.ma@canonical.com>
> ---
>  drivers/net/usb/r8152.c | 14 ++++++++++++++
>  1 file changed, 14 insertions(+)
> 
> diff --git a/drivers/net/usb/r8152.c b/drivers/net/usb/r8152.c
> index f9877a3e83ac..91f4b2761f8e 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;

reverse xmas tree

>  
>  	if (tp->lenovo_macpassthru) {
>  		mac_obj_name = "\\MACA";
> @@ -1662,6 +1664,18 @@ 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) {
> +			rcu_read_unlock();

ret = -EBUSY; or anything but 0, otherwise you get a random MAC from a
calling stack.

Henning

> +			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);