Re: [PATCH] hw/pci: Add parenthesis to PCI_BUILD_BDF macro

["Philippe Mathieu-Daudé" <philmd@linaro.org>]

On 1/11/24 18:59, Roque Arcudia Hernandez wrote:
> The bus parameter in the macro PCI_BUILD_BDF is not surrounded by
> parenthesis. This can create a compile error when warnings are
> treated as errors or can potentially create runtime errors due to the
> operator precedence.
> 
> For instance:
> 
>   file.c:x:32: error: suggest parentheses around '-' inside '<<'
>   [-Werror=parentheses]
>     171 | uint16_t bdf = PCI_BUILD_BDF(a - b, sdev->devfn);
>         |                              ~~^~~
>   include/hw/pci/pci.h:19:41: note: in definition of macro
>   'PCI_BUILD_BDF'
>      19 | #define PCI_BUILD_BDF(bus, devfn)     ((bus << 8) | (devfn))
>         |                                         ^~~
>   cc1: all warnings being treated as errors
> 
> Signed-off-by: Roque Arcudia Hernandez <roqueh@google.com>
> Reviewed-by: Nabih Estefan <nabihestefan@google.com>
> ---
>   include/hw/pci/pci.h | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/include/hw/pci/pci.h b/include/hw/pci/pci.h
> index 35d4fe0bbf..1daec974da 100644
> --- a/include/hw/pci/pci.h
> +++ b/include/hw/pci/pci.h
> @@ -16,7 +16,7 @@ extern bool pci_available;
>   #define PCI_BUS_NUM(x)          (((x) >> 8) & 0xff)
>   #define PCI_SLOT(devfn)         (((devfn) >> 3) & 0x1f)
>   #define PCI_FUNC(devfn)         ((devfn) & 0x07)
> -#define PCI_BUILD_BDF(bus, devfn)     ((bus << 8) | (devfn))
> +#define PCI_BUILD_BDF(bus, devfn)     (((bus) << 8) | (devfn))
>   #define PCI_BDF_TO_DEVFN(x)     ((x) & 0xff)
>   #define PCI_BUS_MAX             256
>   #define PCI_DEVFN_MAX           256

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>