[PATCH] scsi: ibmvfc: Use 'unsigned int' for single-bit bitfields in 'struct ibmvfc_host'

[Nick Desaulniers]

On Tue, Oct 10, 2023 at 1:32 PM Nathan Chancellor <nathan at kernel.org> wrote:
>
> Clang warns (or errors with CONFIG_WERROR=y) several times along the
> lines of:
>
>   drivers/scsi/ibmvscsi/ibmvfc.c:650:17: warning: implicit truncation from 'int' to a one-bit wide bit-field changes value from 1 to -1 [-Wsingle-bit-bitfield-constant-conversion]
>     650 |                 vhost->reinit = 1;
>         |                               ^ ~
>
> A single-bit signed integer bitfield only has possible values of -1 and
> 0, not 0 and 1 like an unsigned one would. No context appears to check
> the actual value of these bitfields, just whether or not it is zero.
> However, it is easy enough to change the type of the fields to 'unsigned
> int', which keeps the same size in memory and resolves the warning.
>
> Fixes: 5144905884e2 ("scsi: ibmvfc: Use a bitfield for boolean flags")
> Signed-off-by: Nathan Chancellor <nathan at kernel.org>

Thanks for the patch!
Reviewed-by: Nick Desaulniers <ndesaulniers at google.com>

> ---
>  drivers/scsi/ibmvscsi/ibmvfc.h | 18 +++++++++---------
>  1 file changed, 9 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/scsi/ibmvscsi/ibmvfc.h b/drivers/scsi/ibmvscsi/ibmvfc.h
> index 331ecf8254be..745ad5ac7251 100644
> --- a/drivers/scsi/ibmvscsi/ibmvfc.h
> +++ b/drivers/scsi/ibmvscsi/ibmvfc.h
> @@ -892,15 +892,15 @@ struct ibmvfc_host {
>         int init_retries;
>         int discovery_threads;
>         int abort_threads;
> -       int client_migrated:1;
> -       int reinit:1;
> -       int delay_init:1;
> -       int logged_in:1;
> -       int mq_enabled:1;
> -       int using_channels:1;
> -       int do_enquiry:1;
> -       int aborting_passthru:1;
> -       int scan_complete:1;
> +       unsigned int client_migrated:1;
> +       unsigned int reinit:1;
> +       unsigned int delay_init:1;
> +       unsigned int logged_in:1;
> +       unsigned int mq_enabled:1;
> +       unsigned int using_channels:1;
> +       unsigned int do_enquiry:1;
> +       unsigned int aborting_passthru:1;
> +       unsigned int scan_complete:1;
>         int scan_timeout;
>         int events_to_log;
>  #define IBMVFC_AE_LINKUP       0x0001
>
> ---
> base-commit: b6f2e063017b92491976a40c32a0e4b3c13e7d2f
> change-id: 20231010-ibmvfc-fix-bitfields-type-971a07c64ec6
>
> Best regards,
> --
> Nathan Chancellor <nathan at kernel.org>
>
>


-- 
Thanks,
~Nick Desaulniers