Re: [PATCH v5] scsi/ata: Use unsigned int for cmd's type in ioctls in scsi_host_template

Christoph Hellwig
2019-02-08T08:05:01Z

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 <natechancellor@gmail.com>
> Acked-by: Bradley Grove <bgrove@attotech.com>
> Acked-by: Don Brace <don.brace@microsemi.com>
> Reviewed-by: Bart Van Assche <bvanassche@acm.org>
> Tested-by: Nick Desaulniers <ndesaulniers@google.com>

Looks good:

Reviewed-by: Christoph Hellwig <hch@lst.de>