Re: [PATCH] mlx5: allow larger xsk chunk_size
flat view
From: Tariq Toukan <hidden>
Date: 2021-10-14 07:32:45
Also in:
linux-rdma, lkml, llvm
On 10/13/2021 6:02 PM, Arnd Bergmann wrote:
quoted hunk ↗ jump to hunk
From: Arnd Bergmann <arnd@arndb.de> When building with 64KB pages, clang points out that xsk->chunk_size can never be PAGE_SIZE: drivers/net/ethernet/mellanox/mlx5/core/en/xsk/setup.c:19:22: error: result of comparison of constant 65536 with expression of type 'u16' (aka 'unsigned short') is always false [-Werror,-Wtautological-constant-out-of-range-compare] if (xsk->chunk_size > PAGE_SIZE || ~~~~~~~~~~~~~~~ ^ ~~~~~~~~~ I'm not familiar with the details of this code, but from a quick look I found that it gets assigned from a 32-bit variable that can be PAGE_SIZE, and that the layout of 'xsk' is not part of an ABI or a hardware structure, so extending the members to 32 bits as well should address both the behavior on 64KB page kernels, and the warning I saw. In older versions of this code, using PAGE_SIZE was the only possibility, so this would have never worked on 64KB page kernels, but the patch apparently did not address this case completely. Fixes: 282c0c798f8e ("net/mlx5e: Allow XSK frames smaller than a page") Signed-off-by: Arnd Bergmann <arnd@arndb.de> --- drivers/net/ethernet/mellanox/mlx5/core/en/params.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en/params.h b/drivers/net/ethernet/mellanox/mlx5/core/en/params.h index 879ad46d754e..b4167350b6df 100644 --- a/drivers/net/ethernet/mellanox/mlx5/core/en/params.h +++ b/drivers/net/ethernet/mellanox/mlx5/core/en/params.h@@ -7,8 +7,8 @@ #include "en.h" struct mlx5e_xsk_param { - u16 headroom; - u16 chunk_size; + u32 headroom; + u32 chunk_size;
Hi Arnd, I agree with your arguments about chunk_size. Yet I have mixed feelings about extending the headroom. Predating in-driver code uses u16 for headroom (i.e. [1]), while xsk_pool_get_headroom returns u32. [1] drivers/net/ethernet/mellanox/mlx5/core/en/params.c :: mlx5e_get_linear_rq_headroom As this patch is a fix, let's keep it minimal, only addressing the issue described in title and description. We might want to move headroom to u32 all around the driver in a separate patch to -next.
};
struct mlx5e_lro_param {