Re: [PATCH v4] scsi/ata: Use unsigned int for cmd's type in ioctls in scsi_host_template

Nathan Chancellor
2019-01-28T16:17:37Z

On Mon, Jan 28, 2019 at 04:16:34PM +0000, Don.Brace@microchip.com 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 find into type 'int', which is used for the cmd paremeter 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 to take a negative value, 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>
> Reviewed-by: Bart Van Assche <bvanassche@acm.org>
>
> static void __exit esas2r_exit(void)
> diff --git a/drivers/scsi/hpsa.c b/drivers/scsi/hpsa.c index ff67ef5d5347..28cfd3d01c5a 100644
> --- a/drivers/scsi/hpsa.c
> +++ b/drivers/scsi/hpsa.c
> @@ -251,10 +251,11 @@ static int number_of_controllers;
>
> Acked-by: Don Brace <don.brace@microsemi.com>
>
>
> diff --git a/drivers/scsi/smartpqi/smartpqi_init.c b/drivers/scsi/smartpqi/smartpqi_init.c
> index f564af8949e8..5d9ccbab7581 100644
> --- a/drivers/scsi/smartpqi/smartpqi_init.c
> +++ b/drivers/scsi/smartpqi/smartpqi_init.c
> @@ -6043,7 +6043,8 @@ static int pqi_passthru_ioctl(struct pqi_ctrl_info *ctrl_info, void __user *arg)
> return rc;
> }
>
> Acked-by: Don Brace <don.brace@microsemi.com>
>
>

Thank you for the reply and the review, I really appreciate it :)

Nathan