On 10/13/2021 6:02 PM, Arnd Bergmann wrote:
From: Arnd Bergmann <arnd@xxxxxxxx>
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@xxxxxxxx>
---
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 {
