Re: [PATCH 5/6] hw/scsi/megasas: Silent GCC9 duplicated-cond warning

[Richard Henderson <richard.henderson@linaro.org>]

On 12/17/19 7:34 AM, Philippe Mathieu-Daudé wrote:
> GCC9 is confused when building with CFLAG -O3:
> 
>   hw/scsi/megasas.c: In function ‘megasas_scsi_realize’:
>   hw/scsi/megasas.c:2387:26: error: duplicated ‘if’ condition [-Werror=duplicated-cond]
>    2387 |     } else if (s->fw_sge >= 128 - MFI_PASS_FRAME_SIZE) {
>   hw/scsi/megasas.c:2385:19: note: previously used here
>    2385 |     if (s->fw_sge >= MEGASAS_MAX_SGE - MFI_PASS_FRAME_SIZE) {
>   cc1: all warnings being treated as errors
> 
> When this device was introduced in commit e8f943c3bcc, the author
> cared about modularity, using a definition for the firmware limit.
> If we modify the limit, the code is valid. Add a check if the
> definition got modified to a bigger limit.
> 
> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
> ---
> Cc: Hannes Reinecke <hare@suse.com>
> Cc: Paolo Bonzini <pbonzini@redhat.com>
> Cc: Fam Zheng <fam@euphon.net>
> Cc: qemu-block@nongnu.org
> ---
>  hw/scsi/megasas.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/hw/scsi/megasas.c b/hw/scsi/megasas.c
> index de9bd20887..ece1601b66 100644
> --- a/hw/scsi/megasas.c
> +++ b/hw/scsi/megasas.c
> @@ -2382,7 +2382,8 @@ static void megasas_scsi_realize(PCIDevice *dev, Error **errp)
>      if (!s->hba_serial) {
>          s->hba_serial = g_strdup(MEGASAS_HBA_SERIAL);
>      }
> -    if (s->fw_sge >= MEGASAS_MAX_SGE - MFI_PASS_FRAME_SIZE) {
> +    if (MEGASAS_MAX_SGE > 128
> +        && s->fw_sge >= MEGASAS_MAX_SGE - MFI_PASS_FRAME_SIZE) {
>          s->fw_sge = MEGASAS_MAX_SGE - MFI_PASS_FRAME_SIZE;
>      } else if (s->fw_sge >= 128 - MFI_PASS_FRAME_SIZE) {
>          s->fw_sge = 128 - MFI_PASS_FRAME_SIZE;
> 

I'm not keen on this.  It looks to me like the raw 128 case should be removed
-- surely that's the point of the symbolic constant.  But I'll defer if a
maintainer disagrees.


r~