netdev - Re: [PATCH net-next 2/4] net/mlx5: Expose serial numbers in devlink info

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Message-ID: <xtt6lkxht2ewaa7wncf2pq6rkgp7x5deoszfvh3hswrerqzfof@hvlgtcws6qx5>
Date: Wed, 19 Mar 2025 12:39:59 +0100
From: Jiri Pirko <jiri@...nulli.us>
To: Simon Horman <horms@...nel.org>
Cc: netdev@...r.kernel.org, davem@...emloft.net, edumazet@...gle.com, 
	kuba@...nel.org, pabeni@...hat.com, saeedm@...dia.com, leon@...nel.org, 
	tariqt@...dia.com, andrew+netdev@...n.ch, donald.hunter@...il.com, parav@...dia.com
Subject: Re: [PATCH net-next 2/4] net/mlx5: Expose serial numbers in devlink
 info

Tue, Mar 18, 2025 at 06:38:58PM +0100, horms@...nel.org wrote:
>On Tue, Mar 18, 2025 at 04:36:25PM +0100, Jiri Pirko wrote:
>> From: Jiri Pirko <jiri@...dia.com>
>> 
>> Devlink info allows to expose serial number and board serial number
>> Get the values from PCI VPD and expose it.
>> 
>> $ devlink dev info
>> pci/0000:08:00.0:
>>   driver mlx5_core
>>   serial_number e4397f872caeed218000846daa7d2f49
>>   board.serial_number MT2314XZ00YA
>
>Hi Jiri,
>
>I'm sorry if this is is somehow obvious, but what is
>the difference between the serial number and board serial number
>(yes, I do see that they are different numbers :)

Quoting Documentation/networking/devlink/devlink-info.rst:

   * - ``serial_number``
     - Serial number of the device.

       This is usually the serial number of the ASIC, also often available
       in PCI config space of the device in the *Device Serial Number*
       capability.

       The serial number should be unique per physical device.
       Sometimes the serial number of the device is only 48 bits long (the
       length of the Ethernet MAC address), and since PCI DSN is 64 bits long
       devices pad or encode additional information into the serial number.
       One example is adding port ID or PCI interface ID in the extra two bytes.
       Drivers should make sure to strip or normalize any such padding
       or interface ID, and report only the part of the serial number
       which uniquely identifies the hardware. In other words serial number
       reported for two ports of the same device or on two hosts of
       a multi-host device should be identical.

   * - ``board.serial_number``
     - Board serial number of the device.

       This is usually the serial number of the board, often available in
       PCI *Vital Product Data*.


>
>>   versions:
>>       fixed:
>>         fw.psid MT_0000000894
>>       running:
>>         fw.version 28.41.1000
>>         fw 28.41.1000
>>       stored:
>>         fw.version 28.41.1000
>>         fw 28.41.1000
>> auxiliary/mlx5_core.eth.0:
>>   driver mlx5_core.eth
>> pci/0000:08:00.1:
>>   driver mlx5_core
>>   serial_number e4397f872caeed218000846daa7d2f49
>>   board.serial_number MT2314XZ00YA
>>   versions:
>>       fixed:
>>         fw.psid MT_0000000894
>>       running:
>>         fw.version 28.41.1000
>>         fw 28.41.1000
>>       stored:
>>         fw.version 28.41.1000
>>         fw 28.41.1000
>> auxiliary/mlx5_core.eth.1:
>>   driver mlx5_core.eth
>> 
>> Signed-off-by: Jiri Pirko <jiri@...dia.com>
>> Reviewed-by: Parav Pandit <parav@...dia.com>
>> ---
>>  .../net/ethernet/mellanox/mlx5/core/devlink.c | 49 +++++++++++++++++++
>>  1 file changed, 49 insertions(+)
>> 
>> diff --git a/drivers/net/ethernet/mellanox/mlx5/core/devlink.c b/drivers/net/ethernet/mellanox/mlx5/core/devlink.c
>> index 73cd74644378..be0ae26d1582 100644
>> --- a/drivers/net/ethernet/mellanox/mlx5/core/devlink.c
>> +++ b/drivers/net/ethernet/mellanox/mlx5/core/devlink.c
>> @@ -35,6 +35,51 @@ static u16 mlx5_fw_ver_subminor(u32 version)
>>  	return version & 0xffff;
>>  }
>>  
>> +static int mlx5_devlink_serial_numbers_put(struct mlx5_core_dev *dev,
>> +					   struct devlink_info_req *req,
>> +					   struct netlink_ext_ack *extack)
>> +{
>> +	struct pci_dev *pdev = dev->pdev;
>> +	unsigned int vpd_size, kw_len;
>> +	char *str, *end;
>> +	u8 *vpd_data;
>> +	int start;
>> +	int err;
>> +
>> +	vpd_data = pci_vpd_alloc(pdev, &vpd_size);
>> +	if (IS_ERR(vpd_data))
>> +		return 0;
>> +
>> +	start = pci_vpd_find_ro_info_keyword(vpd_data, vpd_size,
>> +					     PCI_VPD_RO_KEYWORD_SERIALNO, &kw_len);
>> +	if (start >= 0) {
>> +		str = kstrndup(vpd_data + start, kw_len, GFP_KERNEL);
>> +		if (!str) {
>> +			err = -ENOMEM;
>> +			goto end;
>> +		}
>> +		end = strchrnul(str, ' ');
>> +		*end = '\0';
>> +		err = devlink_info_board_serial_number_put(req, str);
>> +		kfree(str);
>> +	}
>> +
>> +	start = pci_vpd_find_ro_info_keyword(vpd_data, vpd_size, "V3", &kw_len);
>> +	if (start >= 0) {
>> +		str = kstrndup(vpd_data + start, kw_len, GFP_KERNEL);
>> +		if (!str) {
>> +			err = -ENOMEM;
>> +			goto end;
>> +		}
>> +		err = devlink_info_serial_number_put(req, str);
>> +		kfree(str);
>> +	}
>> +
>> +end:
>> +	kfree(vpd_data);
>> +	return err;
>
>Perhaps it can never happen, but Smatch flags that err may be used
>uninitialised here. I believe that can theoretically occur if
>neither of start condition above are met.

Will init.

>
>> +}
>> +
>
>...