Subject: Re: [PATCH] net/mlx5: reduce stack usage in qp_read_field

From: Leon Romanovsky <[email-masked]>
Date: Thu, 30 Apr 2020 08:21:57 +0300

On Tue, Apr 28, 2020 at 11:23:47PM +0200, Arnd Bergmann wrote:
> Moving the mlx5_ifc_query_qp_out_bits structure on the stack was a bit
> excessive and now causes the compiler to complain on 32-bit architectures:
>
> drivers/net/ethernet/mellanox/mlx5/core/debugfs.c: In function 'qp_read_field':
> drivers/net/ethernet/mellanox/mlx5/core/debugfs.c:274:1: error: the frame size of 1104 bytes is larger than 1024 bytes [-Werror=frame-larger-than=]
>
> Revert the previous patch partially to use dynamically allocation as
> the code did before. Unfortunately there is no good error handling
> in case the allocation fails.
>
> Fixes: 57a6c5e992f5 ("net/mlx5: Replace hand written QP context struct with automatic getters")
> Signed-off-by: Arnd Bergmann <[email-masked]>
> ---
>  drivers/net/ethernet/mellanox/mlx5/core/debugfs.c | 12 +++++++++---
>  1 file changed, 9 insertions(+), 3 deletions(-)

Thanks Arnd, I'll pick it to mlx5-next.

I was under impression that the frame size was increased a long
time ago. Is this 1K limit still effective for all archs?
Or is it is 32-bit leftover?

Thanks