Re: [Xen-devel] [PATCH] libxl: correct libxl to obey libxl's programming paramdigm

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Wed, Jul 30, 2014 at 12:18:55PM -0400, Meng Xu wrote:
> When sched_domain_get() return rc != 0, scinfo will not be disposed.
> This violates the libxl programming paradigm:
> 272  * The user must always calls "dispose" exactly
> 273  * once afterwards, to clean up, regardless of whether operations
> on
> 274  * this object succeeded or failed.
> 

I would remove the line number because the header file changes as much
sutffs added in.

> Signed-off-by: Meng Xu <mengxu@xxxxxxxxxxxxx>
> ---
>  tools/libxl/xl_cmdimpl.c |    9 ++++++---
>  1 file changed, 6 insertions(+), 3 deletions(-)
> 
> diff --git a/tools/libxl/xl_cmdimpl.c b/tools/libxl/xl_cmdimpl.c
> index 01bce2f..d1efdd7 100644
> --- a/tools/libxl/xl_cmdimpl.c
> +++ b/tools/libxl/xl_cmdimpl.c
> @@ -5014,7 +5014,7 @@ static int sched_credit_domain_output(int domid)
>      }
>      rc = sched_domain_get(LIBXL_SCHEDULER_CREDIT, domid, &scinfo);
>      if (rc)
> -        return rc;
> +        goto out;
>      domname = libxl_domid_to_name(ctx, domid);
>      printf("%-33s %4d %6d %4d\n",
>          domname,
> @@ -5022,6 +5022,7 @@ static int sched_credit_domain_output(int domid)
>          scinfo.weight,
>          scinfo.cap);
>      free(domname);
> +out:
>      libxl_domain_sched_params_dispose(&scinfo);

And you seem to miss this part of that paradigm:

* IDL-generated libxl types should be used as follows: the user must           
* always call the "init" function before using a type, even if the             
* variable is simply being passed by reference as an out parameter             
* to a libxl function.

So calling dispose in the end while not calling init at the beginning is
still bogus.

Wei.

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