Re: [Xen-devel] [PATCH v2 09/10] libxl: Fix libxl_set_memory_target return value

[George Dunlap <George.Dunlap@xxxxxxxxxxxxx>]

On Wed, Apr 6, 2016 at 12:46 PM, Paulina Szubarczyk
<paulinaszubarczyk@xxxxxxxxx> wrote:
> From: George Dunlap <George.Dunlap@xxxxxxxxxxxxx>
>
> libxl_set_memory_target seems to have the following return values:
>
> * 1 on failure, if the failure happens because of a xenstore error *or*
> * invalid target
>
> * -1 if the setmaxmem hypercall
>
> * -errno if the set_pod_target hypercall target fails
>
> * 0 on success
>
> Make it consistently return ERROR_FAIL on failure, unless the
> parameters were invalid, in which case return ERROR_INVAL.
>
> In accordance with CODING_SYTLE:
>
> 1. Leave rc uninitialized, and set when an error is detected
>
> 2. Use 'r' for return values to functions whose return values are a
> different error space (like xc_domain_setmaxmem and
> xc_domain_set_pod_target)
>
> ---
> Changed since v1:
>
> 3. Use 'lrc' for return values to local functions libxl__*
> where a failure means retry, rather than fail the whole function
> (libxl__fill_dom0_memory_info), to reduce the risk of that.
>
> Signed-off-by: George Dunlap <George.Dunlap@xxxxxxxxxxxxx>
> Signed-off-by: Paulina Szubarczyk <paulinaszubarczyk@xxxxxxxxx>

FYI everything after the "---" will be discarded on commit; so you
need all the tags (signed-off-by, acked-by, &c) to be before that.

 -George

> ---
>  tools/libxl/libxl.c | 28 ++++++++++++++++++----------
>  1 file changed, 18 insertions(+), 10 deletions(-)
>
> diff --git a/tools/libxl/libxl.c b/tools/libxl/libxl.c
> index 75f00be..057366e 100644
> --- a/tools/libxl/libxl.c
> +++ b/tools/libxl/libxl.c
> @@ -4824,7 +4824,7 @@ int libxl_set_memory_target(libxl_ctx *ctx, uint32_t 
> domid,
>          int32_t target_memkb, int relative, int enforce)
>  {
>      GC_INIT(ctx);
> -    int rc = 1, abort_transaction = 0;
> +    int rc, r, lrc, abort_transaction = 0;
>      uint64_t memorykb;
>      uint32_t videoram = 0;
>      uint32_t current_target_memkb = 0, new_target_memkb = 0;
> @@ -4852,15 +4852,15 @@ retry_transaction:
>      if (!target && !domid) {
>          if (!xs_transaction_end(ctx->xsh, t, 1))
>              goto out_no_transaction;
> -        rc = libxl__fill_dom0_memory_info(gc, &current_target_memkb,
> +        lrc = libxl__fill_dom0_memory_info(gc, &current_target_memkb,
>                                            &current_max_memkb);
> -        if (rc < 0)
> -            goto out_no_transaction;
> +        if (lrc < 0) { rc = ERROR_FAIL; goto out_no_transaction; }
>          goto retry_transaction;
>      } else if (!target) {
>          LOGE(ERROR, "cannot get target memory info from %s/memory/target",
>               dompath);
>          abort_transaction = 1;
> +        rc = ERROR_FAIL;
>          goto out;
>      } else {
>          current_target_memkb = strtoul(target, &endptr, 10);
> @@ -4868,6 +4868,7 @@ retry_transaction:
>              LOGE(ERROR, "invalid memory target %s from %s/memory/target\n",
>                   target, dompath);
>              abort_transaction = 1;
> +            rc = ERROR_FAIL;
>              goto out;
>          }
>      }
> @@ -4876,6 +4877,7 @@ retry_transaction:
>          LOGE(ERROR, "cannot get memory info from %s/memory/static-max",
>               dompath);
>          abort_transaction = 1;
> +        rc = ERROR_FAIL;
>          goto out;
>      }
>      memorykb = strtoul(memmax, &endptr, 10);
> @@ -4883,6 +4885,7 @@ retry_transaction:
>          LOGE(ERROR, "invalid max memory %s from %s/memory/static-max\n",
>               memmax, dompath);
>          abort_transaction = 1;
> +        rc = ERROR_FAIL;
>          goto out;
>      }
>
> @@ -4902,6 +4905,7 @@ retry_transaction:
>              "memory_dynamic_max must be less than or equal to"
>              " memory_static_max\n");
>          abort_transaction = 1;
> +        rc = ERROR_INVAL;
>          goto out;
>      }
>
> @@ -4909,33 +4913,36 @@ retry_transaction:
>          LOG(ERROR, "new target %d for dom0 is below the minimum threshold",
>              new_target_memkb);
>          abort_transaction = 1;
> +        rc = ERROR_INVAL;
>          goto out;
>      }
>
>      if (enforce) {
>          memorykb = new_target_memkb + videoram;
> -        rc = xc_domain_setmaxmem(ctx->xch, domid, memorykb +
> +        r = xc_domain_setmaxmem(ctx->xch, domid, memorykb +
>                  LIBXL_MAXMEM_CONSTANT);
> -        if (rc != 0) {
> +        if (r != 0) {
>              LOGE(ERROR,
>                   "xc_domain_setmaxmem domid=%u memkb=%"PRIu64" failed 
> ""rc=%d\n",
>                   domid,
>                   memorykb + LIBXL_MAXMEM_CONSTANT,
> -                 rc);
> +                 r);
>              abort_transaction = 1;
> +            rc = ERROR_FAIL;
>              goto out;
>          }
>      }
>
> -    rc = xc_domain_set_pod_target(ctx->xch, domid,
> +    r = xc_domain_set_pod_target(ctx->xch, domid,
>              (new_target_memkb + LIBXL_MAXMEM_CONSTANT) / 4, NULL, NULL, 
> NULL);
> -    if (rc != 0) {
> +    if (r != 0) {
>          LOGE(ERROR,
>               "xc_domain_set_pod_target domid=%d, memkb=%d ""failed rc=%d\n",
>               domid,
>               new_target_memkb / 4,
> -             rc);
> +             r);
>          abort_transaction = 1;
> +        rc = ERROR_FAIL;
>          goto out;
>      }
>
> @@ -4949,6 +4956,7 @@ retry_transaction:
>                       "%"PRIu32, new_target_memkb / 1024);
>      libxl_dominfo_dispose(&ptr);
>
> +    rc = 0;
>  out:
>      if (!xs_transaction_end(ctx->xsh, t, abort_transaction)
>          && !abort_transaction)
> --
> 1.9.1
>
>
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