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Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Nathan Chancellor , Jonathan Lemon , Daniel Borkmann , Arnd Bergmann , Nick Desaulniers , Bill Wendling , Justin Stitt , Tariq Toukan , Gal Pressman , netdev@vger.kernel.org, linux-rdma@vger.kernel.org, llvm@lists.linux.dev Subject: Re: [PATCH 8/9] mlx5: stop warning for 64KB pages Message-ID: References: <20240328143051.1069575-1-arnd@kernel.org> <20240328143051.1069575-9-arnd@kernel.org> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240328143051.1069575-9-arnd@kernel.org> On Thu, 28 Mar 2024 at 15:30:46 +0100, Arnd Bergmann wrote: > From: Arnd Bergmann > > 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/ > Link: https://lore.kernel.org/lkml/a7b27541-0ebb-4f2d-bd06-270a4d404613@app.fastmail.com/ > Signed-off-by: Arnd Bergmann > --- > 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 06592b9f0424..9240cfe25d10 100644 > --- a/drivers/net/ethernet/mellanox/mlx5/core/en/xsk/setup.c > +++ b/drivers/net/ethernet/mellanox/mlx5/core/en/xsk/setup.c > @@ -28,8 +28,10 @@ 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 || xsk->chunk_size < MLX5E_MIN_XSK_CHUNK_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) { Acked-by: Maxim Mikityanskiy > mlx5_core_err(mdev, "XSK chunk size %u out of bounds [%u, %lu]\n", xsk->chunk_size, > MLX5E_MIN_XSK_CHUNK_SIZE, PAGE_SIZE); > return false; > -- > 2.39.2 >