Re: [PATCH v1 06/19] xen/sysctl: wrap around XEN_SYSCTL_perfc_op

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Wed, 12 Mar 2025, Penny Zheng wrote:
> perfc_control() and perfc_copy_info() are responsible for providing control
> of perf counters via XEN_SYSCTL_perfc_op in DOM0, so they both shall
> be wrapped.
> 
> Signed-off-by: Penny Zheng <Penny.Zheng@xxxxxxx>
> ---
>  xen/common/perfc.c      | 2 ++
>  xen/include/xen/perfc.h | 8 ++++++++
>  2 files changed, 10 insertions(+)
> 
> diff --git a/xen/common/perfc.c b/xen/common/perfc.c
> index 8302b7cf6d..0f3b89af2c 100644
> --- a/xen/common/perfc.c
> +++ b/xen/common/perfc.c
> @@ -149,6 +149,7 @@ void cf_check perfc_reset(unsigned char key)
>      }
>  }
>  
> +#ifdef CONFIG_SYSCTL

I think in this case it would be best to make CONFIG_PERF_COUNTERS
depending on CONFIG_SYSCTL. The consequence is that without
CONFIG_SYSCTL, xen/common/perfc.c will be disabled in the build.



>  static struct xen_sysctl_perfc_desc perfc_d[NR_PERFCTRS];
>  static xen_sysctl_perfc_val_t *perfc_vals;
>  static unsigned int      perfc_nbr_vals;
> @@ -265,6 +266,7 @@ int perfc_control(struct xen_sysctl_perfc_op *pc)
>  
>      return rc;
>  }
> +#endif /* CONFIG_SYSCTL */
>  
>  /*
>   * Local variables:
> diff --git a/xen/include/xen/perfc.h b/xen/include/xen/perfc.h
> index bf0eb032f7..6cc8af12d5 100644
> --- a/xen/include/xen/perfc.h
> +++ b/xen/include/xen/perfc.h
> @@ -5,6 +5,7 @@
>  
>  #include <xen/macros.h>
>  #include <xen/percpu.h>
> +#include <xen/errno.h>
>  
>  /*
>   * NOTE: new counters must be defined in perfc_defn.h
> @@ -92,7 +93,14 @@ DECLARE_PER_CPU(perfc_t[NUM_PERFCOUNTERS], perfcounters);
>  #endif
>  
>  struct xen_sysctl_perfc_op;
> +#ifdef CONFIG_SYSCTL
>  int perfc_control(struct xen_sysctl_perfc_op *pc);
> +#else
> +static inline int perfc_control(struct xen_sysctl_perfc_op *pc)
> +{
> +    return -EOPNOTSUPP;
> +}
> +#endif
>  
>  extern void cf_check perfc_printall(unsigned char key);
>  extern void cf_check perfc_reset(unsigned char key);
> -- 
> 2.34.1
>