Subject: Re: [PATCH net] net/mlx5e: Fix return value in case of module EEPROM read error

From: Simon Horman <[email-masked]>
Date: Wed, 5 Nov 2025 10:27:50 +0000

On Tue, Nov 04, 2025 at 04:15:36PM +0200, Tariq Toukan wrote:
> From: Gal Pressman <[email-masked]>
> 
> mlx5e_get_module_eeprom_by_page() has weird error handling.
> 
> First, it is treating -EINVAL as a special case, but it is unclear why.
> 
> Second, it tries to fail "gracefully" by returning the number of bytes
> read even in case of an error. This results in wrongly returning
> success (0 return value) if the error occurs before any bytes were
> read.
> 
> Simplify the error handling by returning an error when such occurs. This
> also aligns with the error handling we have in mlx5e_get_module_eeprom()
> for the old API.
> 
> This fixes the following case where the query fails, but userspace
> ethtool wrongly treats it as success and dumps an output:
> 
>   # ethtool -m eth2
>   netlink warning: mlx5_core: Query module eeprom by page failed, read 0 bytes, err -5
>   netlink warning: mlx5_core: Query module eeprom by page failed, read 0 bytes, err -5
>   Offset		Values
>   ------		------
>   0x0000:		00 00 00 00 05 00 04 00 00 00 00 00 05 00 05 00
>   0x0010:		00 00 00 00 05 00 06 00 50 00 00 00 67 65 20 66
>   0x0020:		61 69 6c 65 64 2c 20 72 65 61 64 20 30 20 62 79
>   0x0030:		74 65 73 2c 20 65 72 72 20 2d 35 00 14 00 03 00
>   0x0040:		08 00 01 00 03 00 00 00 08 00 02 00 1a 00 00 00
>   0x0050:		14 00 04 00 08 00 01 00 04 00 00 00 08 00 02 00
>   0x0060:		0e 00 00 00 14 00 05 00 08 00 01 00 05 00 00 00
>   0x0070:		08 00 02 00 1a 00 00 00 14 00 06 00 08 00 01 00
> 
> Fixes: e109d2b204da ("net/mlx5: Implement get_module_eeprom_by_page()")
> Signed-off-by: Gal Pressman <[email-masked]>
> Reviewed-by: Alex Lazar <[email-masked]>
> Signed-off-by: Tariq Toukan <[email-masked]>

Thanks for the detailed description.

Reviewed-by: Simon Horman <[email-masked]>