Re: [PATCH 10/10] libxl: libxl_tmem functions improving coding style

["Roger Pau Monné" <roger.pau@citrix.com>]

On Fri, 1 Apr 2016, Paulina Szubarczyk wrote:

> In accordance with CODING_SYTLE:
>  - Use 'r' for return values to functions whose return values are a
>    different error space (like xc_tmem_control, xc_tmem_auth)
> 
> Signed-off-by: Paulina Szubarczyk <paulinaszubarczyk@gmail.com>
> ---
>  tools/libxl/libxl.c | 58 ++++++++++++++++++++++++++---------------------------
>  1 file changed, 29 insertions(+), 29 deletions(-)
> 
> diff --git a/tools/libxl/libxl.c b/tools/libxl/libxl.c
> index 6bb2f82..5794ade 100644
> --- a/tools/libxl/libxl.c
> +++ b/tools/libxl/libxl.c
> @@ -6107,14 +6107,14 @@ uint32_t libxl_vm_get_start_time(libxl_ctx *ctx, uint32_t domid)
>  
>  char *libxl_tmem_list(libxl_ctx *ctx, uint32_t domid, int use_long)
>  {
> -    int rc;
> +    int r;
>      char _buf[32768];
>      GC_INIT(ctx);
>  
> -    rc = xc_tmem_control(ctx->xch, -1, XEN_SYSCTL_TMEM_OP_LIST, domid, 32768, use_long,
> +    r = xc_tmem_control(ctx->xch, -1, XEN_SYSCTL_TMEM_OP_LIST, domid, 32768, use_long,
>                           _buf);
> -    if (rc < 0) {
> -        LOGEV(ERROR, rc, "Can not get tmem list");
> +    if (r < 0) {
> +        LOGEV(ERROR, r, "Can not get tmem list");
>          GC_FREE;
>          return NULL;
>      }
> @@ -6125,36 +6125,36 @@ char *libxl_tmem_list(libxl_ctx *ctx, uint32_t domid, int use_long)
>  
>  int libxl_tmem_freeze(libxl_ctx *ctx, uint32_t domid)
>  {
> -    int rc;
> +    int r;
>      GC_INIT(ctx);
>  
> -    rc = xc_tmem_control(ctx->xch, -1, XEN_SYSCTL_TMEM_OP_FREEZE, domid, 0, 0,
> +    r = xc_tmem_control(ctx->xch, -1, XEN_SYSCTL_TMEM_OP_FREEZE, domid, 0, 0,
>                           NULL);
> -    if (rc < 0) {
> -        LOGEV(ERROR, rc, "Can not freeze tmem pools");
> +    if (r < 0) {
> +        LOGEV(ERROR, r, "Can not freeze tmem pools");
>          GC_FREE;
>          return ERROR_FAIL;
>      }
>  
>      GC_FREE;
> -    return rc;
> +    return r;

This is conceptually wrong IMHO, you are returning an error code that's 
not in libxl space from a libxl function (although due to the "return" 
above this is always going to be 0). I would just return 0 here, or add an 
"out" label, keep rc and set it in the error case above replacing the 
return with a goto out.

Roger.

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