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[142.68.80.239]) by smtp.gmail.com with ESMTPSA id o23-20020a544797000000b003c3d1b47532sm2495301oic.49.2024.04.03.08.45.35 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 03 Apr 2024 08:45:35 -0700 (PDT) Received: from jgg by wakko with local (Exim 4.95) (envelope-from ) id 1rs2nu-007hVG-P9; Wed, 03 Apr 2024 12:45:34 -0300 Date: Wed, 3 Apr 2024 12:45:34 -0300 From: Jason Gunthorpe To: Arnd Bergmann Cc: linux-kernel@vger.kernel.org, Leon Romanovsky , Nathan Chancellor , Arnd Bergmann , Nick Desaulniers , Bill Wendling , Justin Stitt , Kees Cook , "Gustavo A. R. Silva" , linux-rdma@vger.kernel.org, llvm@lists.linux.dev Subject: Re: [PATCH 7/9] infiniband: uverbs: avoid out-of-range warnings Message-ID: <20240403154534.GE1363414@ziepe.ca> References: <20240328143051.1069575-1-arnd@kernel.org> <20240328143051.1069575-8-arnd@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@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: <20240328143051.1069575-8-arnd@kernel.org> On Thu, Mar 28, 2024 at 03:30:45PM +0100, Arnd Bergmann wrote: > From: Arnd Bergmann > > clang warns for comparisons that are always true, which is the case > for these two page size checks on architectures with 64KB pages: > > drivers/infiniband/core/uverbs_ioctl.c:90:39: 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] > WARN_ON_ONCE(method_elm->bundle_size > PAGE_SIZE); > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~ > include/asm-generic/bug.h:104:25: note: expanded from macro 'WARN_ON_ONCE' > int __ret_warn_on = !!(condition); \ > ^~~~~~~~~ > drivers/infiniband/core/uverbs_ioctl.c:621:17: 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 (hdr.length > PAGE_SIZE || > ~~~~~~~~~~ ^ ~~~~~~~~~ > > Add a cast to u32 in both cases, so it never warns about this. But doesn't that hurt the codegen? Jason