[PATCH] net/mlx5: fix uninitialized warning

[Stephen Hemminger]

On Thu, 13 Nov 2025 08:33:01 -0800
Stephen Hemminger <stephen at networkplumber.org> wrote:

> Gcc-16 detects use of uninitialized variable.
> ./drivers/net/mlx5/linux/mlx5_ethdev_os.c: In function ‘mlx5_link_update’:
> ../drivers/net/mlx5/linux/mlx5_ethdev_os.c:539:15: warning: ‘*(long unsigned int *)((char *)&dev_link + offsetof(struct rte_eth_link, <U38c0>))’ may be used uninitialized [-Wmaybe-uninitialized]
>   539 |         ret = !!memcmp(&dev->data->dev_link, &dev_link,
>       |               ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>   540 |                        sizeof(struct rte_eth_link));
>       |                        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> ../drivers/net/mlx5/linux/mlx5_ethdev_os.c:515:29: note: ‘*(long unsigned int *)((char *)&dev_link + offsetof(struct rte_eth_link, <U38c0>))’ was declared here
>   515 |         struct rte_eth_link dev_link;
>       |
> 
> If the retry loop exits the code would do memcmp against unintialized
> stack value. Resolve by intializing to zero.
> 
> Fixes: 1256805dd54d ("net/mlx5: move Linux-specific functions")
> Cc: stable at dpdk.org
> 
> Signed-off-by: Stephen Hemminger <stephen at networkplumber.org>
> ---

The build fails with clang because of the (annoying) use of pedantic in this driver.
I will let mlx5 maintainers fix it then.

../drivers/net/mlx5/linux/mlx5_ethdev_os.c:515:33: error: use of GNU empty initializer extension [-Werror,-Wgnu-empty-initializer]
        struct rte_eth_link dev_link = { };