Re: [PATCH 8/9] mlx5: stop warning for 64KB pages

From: Tariq Toukan <ttoukan.linux@gmail.com>
To: Arnd Bergmann <arnd@kernel.org>,
	linux-kernel@vger.kernel.org, Saeed Mahameed <saeedm@nvidia.com>,
	Leon Romanovsky <leon@kernel.org>,
	"David S. Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
	Nathan Chancellor <nathan@kernel.org>,
	Jonathan Lemon <jonathan.lemon@gmail.com>,
	Maxim Mikityanskiy <maxtram95@gmail.com>,
	Daniel Borkmann <daniel@iogearbox.net>
Cc: Arnd Bergmann <arnd@arndb.de>,
	Nick Desaulniers <ndesaulniers@google.com>,
	Bill Wendling <morbo@google.com>,
	Justin Stitt <justinstitt@google.com>,
	Gal Pressman <gal@nvidia.com>,
	netdev@vger.kernel.org, linux-rdma@vger.kernel.org,
	llvm@lists.linux.dev, Tariq Toukan <tariqt@nvidia.com>
Subject: Re: [PATCH 8/9] mlx5: stop warning for 64KB pages
Date: Fri, 29 Mar 2024 00:39:23 +0200	[thread overview]
Message-ID: <d8381c87-6123-4df0-97d3-ea8d0e17c6bb@gmail.com> (raw)
In-Reply-To: <20240328143051.1069575-9-arnd@kernel.org>

On 28/03/2024 16:30, Arnd Bergmann wrote:
> 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/
> Link: https://lore.kernel.org/lkml/a7b27541-0ebb-4f2d-bd06-270a4d404613@app.fastmail.com/
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Thanks for your patch.

Reviewed-by: Tariq Toukan <tariqt@nvidia.com>