From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: Re: [PATCH v5] scsi/ata: Use unsigned int for cmd's type in ioctls in scsi_host_template Date: Fri, 8 Feb 2019 00:05:01 -0800 Message-ID: <20190208080501.GA18530@infradead.org> References: <20190126075256.29608-1-natechancellor@gmail.com> <20190207160719.28895-1-natechancellor@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20190207160719.28895-1-natechancellor@gmail.com> Sender: linux-kernel-owner@vger.kernel.org To: Nathan Chancellor Cc: Jens Axboe , "James E.J. Bottomley" , "Martin K. Petersen" , "Manoj N. Kumar" , "Matthew R. Ochs" , Uma Krishnan , Brian King , Adaptec OEM Raid Solutions , Marc Gonzalez , linux-ide@vger.kernel.org, linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org, esc.storagedev@microsemi.com, Bradley Grove , Don Brace , Bart Van Assche , Nick Desaulniers List-Id: linux-ide@vger.kernel.org On Thu, Feb 07, 2019 at 09:07:20AM -0700, Nathan Chancellor wrote: > Clang warns several times in the scsi subsystem (trimmed for brevity): > > drivers/scsi/hpsa.c:6209:7: warning: overflow converting case value to > switch condition type (2147762695 to 18446744071562347015) [-Wswitch] > case CCISS_GETBUSTYPES: > ^ > drivers/scsi/hpsa.c:6208:7: warning: overflow converting case value to > switch condition type (2147762694 to 18446744071562347014) [-Wswitch] > case CCISS_GETHEARTBEAT: > ^ > > The root cause is that the _IOC macro can generate really large numbers, > which don't fit into type 'int', which is used for the cmd parameter in > the ioctls in scsi_host_template. My research into how GCC and Clang are > handling this at a low level didn't prove fruitful. However, looking at > the rest of the kernel tree, all ioctls use an 'unsigned int' for the > cmd parameter, which will fit all of the _IOC values in the scsi/ata > subsystems. > > Make that change because none of the ioctls expect a negative value for > any command, it brings the ioctls inline with the reset of the kernel, > and it removes ambiguity, which is never good when dealing with compilers. > > Link: https://github.com/ClangBuiltLinux/linux/issues/85 > Link: https://github.com/ClangBuiltLinux/linux/issues/154 > Link: https://github.com/ClangBuiltLinux/linux/issues/157 > Signed-off-by: Nathan Chancellor > Acked-by: Bradley Grove > Acked-by: Don Brace > Reviewed-by: Bart Van Assche > Tested-by: Nick Desaulniers Looks good: Reviewed-by: Christoph Hellwig