Re: [Xen-devel] [PATCH 1/2] libxl: modify domain config when moving domain to another cpupool

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Tue, Oct 02, 2018 at 04:19:33PM +0200, Juergen Gross wrote:
> Today the domain config info contains the cpupool name the domain was
> started in only if the cpupool was specified at domain creation. Moving
> the domain to another cpupool later won't change that information.
> 
> Correct that by modifying the domain config accordingly.
> 
> Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
> ---
>  tools/libxl/libxl_cpupool.c | 28 +++++++++++++++++++++++++---
>  1 file changed, 25 insertions(+), 3 deletions(-)
> 
> diff --git a/tools/libxl/libxl_cpupool.c b/tools/libxl/libxl_cpupool.c
> index 85b06882db..92cf29bc6b 100644
> --- a/tools/libxl/libxl_cpupool.c
> +++ b/tools/libxl/libxl_cpupool.c
> @@ -430,17 +430,39 @@ out:
>  int libxl_cpupool_movedomain(libxl_ctx *ctx, uint32_t poolid, uint32_t domid)
>  {
>      GC_INIT(ctx);
> +    libxl_domain_config d_config;
> +    libxl__domain_userdata_lock *lock = NULL;
>      int rc;
>  
> +    libxl_domain_config_init(&d_config);
> +
>      rc = xc_cpupool_movedomain(ctx->xch, poolid, domid);
>      if (rc) {
>          LOGEVD(ERROR, rc, domid, "Error moving domain to cpupool");
> -        GC_FREE;
> -        return ERROR_FAIL;
> +        rc = ERROR_FAIL;
> +        goto out;
> +    }
> +
> +    lock = libxl__lock_domain_userdata(gc, domid);
> +    if (!lock) {
> +        rc = ERROR_LOCK_FAIL;
> +        goto out;
>      }

It is better to move the lock before calling xc_cpupool_movedomain to
avoid races when there are multiple callers of libxl_cpupool_movedomain.

Wei.

>  
> +    rc = libxl__get_domain_configuration(gc, domid, &d_config);
> +    if (rc)
> +        goto out;
> +
> +    free(d_config.c_info.pool_name);
> +    d_config.c_info.pool_name = libxl_cpupoolid_to_name(ctx, poolid);
> +
> +    rc = libxl__set_domain_configuration(gc, domid, &d_config);
> +
> +out:
> +    if (lock) libxl__unlock_domain_userdata(lock);
> +    libxl_domain_config_dispose(&d_config);
>      GC_FREE;
> -    return 0;
> +    return rc;
>  }
>  
>  /*
> -- 
> 2.16.4
> 

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