Re: [Xen-devel] [PATCH] xen/arm: Fix ARM build following c/s 11c397c

[Julien Grall <julien.grall@xxxxxxx>]

Hi Andrew,

On 08/02/17 19:10, Andrew Cooper wrote:
> c/s 11c397c broke the ARM build by introducing a common ACCESS_ONCE() which is
> different to the definiton in smmu.c
>
> The SMMU code included a scalar typecheck, which is worth keeping in the
> common case, given ACCESS_ONCE()'s restrictions.  However, express the
> typecheck differently so as to avoid Coverity compliants about unused
s/compliants/complaint/

> variables.
OOI, the variable is marked as "__maybe_unused", so why Coverity would 
complaint?
> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Acked-by: Julien Grall <julien.grall@xxxxxxx>

Cheers,

> ---
> CC: Jan Beulich <JBeulich@xxxxxxxx>
> CC: Stefano Stabellini <sstabellini@xxxxxxxxxx>
> CC: Julien Grall <julien.grall@xxxxxxx>
> ---
>  xen/drivers/passthrough/arm/smmu.c | 10 ----------
>  xen/include/xen/lib.h              |  5 ++++-
>  2 files changed, 4 insertions(+), 11 deletions(-)
>
> diff --git a/xen/drivers/passthrough/arm/smmu.c 
> b/xen/drivers/passthrough/arm/smmu.c
> index cf8b8b8..06c0a45 100644
> --- a/xen/drivers/passthrough/arm/smmu.c
> +++ b/xen/drivers/passthrough/arm/smmu.c
> @@ -198,16 +198,6 @@ typedef paddr_t phys_addr_t;
>
>  #define VA_BITS                0       /* Only used for configuring stage-1 
> input size */
>
> -/* The macro ACCESS_ONCE start to be replaced in Linux in favor of
> - * {READ, WRITE}_ONCE. Rather than introducing in the common code, keep a
> - * version here. We will have to drop it when the SMMU code in Linux will
> - * switch to {READ, WRITE}_ONCE.
> - */
> -#define __ACCESS_ONCE(x) ({ \
> -        __maybe_unused typeof(x) __var = 0; \
> -       (volatile typeof(x) *)&(x); })
> -#define ACCESS_ONCE(x) (*__ACCESS_ONCE(x))
> -
>  #define MODULE_DEVICE_TABLE(type, name)
>  #define module_param_named(name, value, type, perm)
>  #define MODULE_PARM_DESC(_parm, desc)
> diff --git a/xen/include/xen/lib.h b/xen/include/xen/lib.h
> index 1976e4b..995a85a 100644
> --- a/xen/include/xen/lib.h
> +++ b/xen/include/xen/lib.h
> @@ -56,7 +56,10 @@
>
>  #define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]) + __must_be_array(x))
>
> -#define ACCESS_ONCE(x) (*(volatile typeof(x) *)&(x))
> +#define __ACCESS_ONCE(x) ({                             \
> +            (void)(typeof(x))0; /* Scalar typecheck. */ \
> +            (volatile typeof(x) *)&(x); })
> +#define ACCESS_ONCE(x) (*__ACCESS_ONCE(x))
>
>  #define MASK_EXTR(v, m) (((v) & (m)) / ((m) & -(m)))
>  #define MASK_INSR(v, m) (((v) * ((m) & -(m))) & (m))
--
Julien Grall

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
https://lists.xen.org/xen-devel