| Message ID | 20211015152056.2434853-1-arnd@kernel.org (mailing list archive) |
|---|---|
| State | Not Applicable |
| Headers | show |
| Series | [v2] mlx5: stop warning for 64KB pages | expand |
From: Arnd Bergmann > Sent: 15 October 2021 16:21 > > 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 || > ~~~~~~~~~~~~~~~ ^ ~~~~~~~~~ > > 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. > > As Maxim Mikityanskiy suggested, 64KB chunks are really not all that > useful, so just shut up the warning by adding a cast. > > Fixes: 282c0c798f8e ("net/mlx5e: Allow XSK frames smaller than a page") > Link: https://lore.kernel.org/netdev/20211013150232.2942146-1-arnd@kernel.org/ > Signed-off-by: Arnd Bergmann <arnd@arndb.de> > --- > drivers/net/ethernet/mellanox/mlx5/core/en/xsk/setup.c | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > > diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en/xsk/setup.c > b/drivers/net/ethernet/mellanox/mlx5/core/en/xsk/setup.c > index 538bc2419bd8..228257010f32 100644 > --- a/drivers/net/ethernet/mellanox/mlx5/core/en/xsk/setup.c > +++ b/drivers/net/ethernet/mellanox/mlx5/core/en/xsk/setup.c > @@ -15,8 +15,10 @@ bool mlx5e_validate_xsk_param(struct mlx5e_params *params, > struct mlx5e_xsk_param *xsk, > struct mlx5_core_dev *mdev) > { > - /* AF_XDP doesn't support frames larger than PAGE_SIZE. */ > - if (xsk->chunk_size > PAGE_SIZE || > + /* AF_XDP doesn't support frames larger than PAGE_SIZE, > + * and xsk->chunk_size is limited to 65535 bytes. > + */ > + if ((size_t)xsk->chunk_size > PAGE_SIZE || > xsk->chunk_size < MLX5E_MIN_XSK_CHUNK_SIZE) > return false; How much smaller does the kernel get if you change 'chunk_size' from _u16 to 'unsigned int'. ? Especially for a non-x86 build? Or is it a hardware constrained size?? David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en/xsk/setup.c b/drivers/net/ethernet/mellanox/mlx5/core/en/xsk/setup.c index 538bc2419bd8..228257010f32 100644 --- a/drivers/net/ethernet/mellanox/mlx5/core/en/xsk/setup.c +++ b/drivers/net/ethernet/mellanox/mlx5/core/en/xsk/setup.c @@ -15,8 +15,10 @@ bool mlx5e_validate_xsk_param(struct mlx5e_params *params, struct mlx5e_xsk_param *xsk, struct mlx5_core_dev *mdev) { - /* AF_XDP doesn't support frames larger than PAGE_SIZE. */ - if (xsk->chunk_size > PAGE_SIZE || + /* AF_XDP doesn't support frames larger than PAGE_SIZE, + * and xsk->chunk_size is limited to 65535 bytes. + */ + if ((size_t)xsk->chunk_size > PAGE_SIZE || xsk->chunk_size < MLX5E_MIN_XSK_CHUNK_SIZE) return false;