Re: [Xen-devel] [PATCH] xen/pvcalls: use WARN_ON(1) instead of __WARN()

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Fri, 21 Jul 2017, Arnd Bergmann wrote:
> __WARN() is an internal helper that is only available on
> some architectures, but causes a build error e.g. on ARM64
> in some configurations:
> 
> drivers/xen/pvcalls-back.c: In function 'set_backend_state':
> drivers/xen/pvcalls-back.c:1097:5: error: implicit declaration of function 
> '__WARN' [-Werror=implicit-function-declaration]
> 
> Unfortunately, there is no equivalent of BUG() that takes no
> arguments, but WARN_ON(1) is commonly used in other drivers
> and works on all configurations.
> 
> Fixes: 7160378206b2 ("xen/pvcalls: xenbus state handling")
> Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>

Reviewed-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>


> ---
>  drivers/xen/pvcalls-back.c | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/xen/pvcalls-back.c b/drivers/xen/pvcalls-back.c
> index d6c4c4aecb41..00c1a2344330 100644
> --- a/drivers/xen/pvcalls-back.c
> +++ b/drivers/xen/pvcalls-back.c
> @@ -1094,7 +1094,7 @@ static void set_backend_state(struct xenbus_device *dev,
>                               xenbus_switch_state(dev, XenbusStateClosing);
>                               break;
>                       default:
> -                             __WARN();
> +                             WARN_ON(1);
>                       }
>                       break;
>               case XenbusStateInitWait:
> @@ -1109,7 +1109,7 @@ static void set_backend_state(struct xenbus_device *dev,
>                               xenbus_switch_state(dev, XenbusStateClosing);
>                               break;
>                       default:
> -                             __WARN();
> +                             WARN_ON(1);
>                       }
>                       break;
>               case XenbusStateConnected:
> @@ -1123,7 +1123,7 @@ static void set_backend_state(struct xenbus_device *dev,
>                               xenbus_switch_state(dev, XenbusStateClosing);
>                               break;
>                       default:
> -                             __WARN();
> +                             WARN_ON(1);
>                       }
>                       break;
>               case XenbusStateClosing:
> @@ -1134,11 +1134,11 @@ static void set_backend_state(struct xenbus_device 
> *dev,
>                               xenbus_switch_state(dev, XenbusStateClosed);
>                               break;
>                       default:
> -                             __WARN();
> +                             WARN_ON(1);
>                       }
>                       break;
>               default:
> -                     __WARN();
> +                     WARN_ON(1);
>               }
>       }
>  }
> -- 
> 2.9.0
> 

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