[libvirt] [PATCH] libxl: libxl_get_max_cpus returning a libxl error from 4.4 onward

[Martin Kletzander]

On Tue, Dec 17, 2013 at 06:43:25PM +0100, Dario Faggioli wrote:
> Starting from commit 2e82c18c in Xen (will be included in Xen 4.4)
> libxl_get_max_cpus() start returning a proper libxl error code, in
> case of failure. It returning 0 is now basically impossible but,
> theoretically, still wrong, not to mention that using '<= 0' makes
> this correct for both Xen 4.4 and Xen 4.3 (and 4.2). That's why we
> go for it (rather than just '< 0').
>
> Signed-off-by: Dario Faggioli <dario.faggioli at citrix.com>
> Cc: Jim Fehlig <jfehlig at suse.com>
> Cc: Ian Jackson <Ian.Jackson at eu.citrix.com>
> ---
>  src/libxl/libxl_driver.c |    8 +++++---
>  1 file changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/src/libxl/libxl_driver.c b/src/libxl/libxl_driver.c
> index 692c3b7..a31b094 100644
> --- a/src/libxl/libxl_driver.c
> +++ b/src/libxl/libxl_driver.c
> @@ -1101,9 +1101,11 @@ libxlConnectGetMaxVcpus(virConnectPtr conn, const char *type ATTRIBUTE_UNUSED)
>
>      cfg = libxlDriverConfigGet(driver);
>      ret = libxl_get_max_cpus(cfg->ctx);
> -    /* libxl_get_max_cpus() will return 0 if there were any failures,
> -       e.g. xc_physinfo() failing */
> -    if (ret == 0)
> +    /* On failure, libxl_get_max_cpus() will return ERROR_FAIL from Xen 4.4
> +     * onward, but it ever returning 0 is obviously wrong too (and it is
> +     * what happens, on failure, on Xen 4.3 and earlier). Therefore, a 'less
> +     * or equal' is the catchall we want. */
> +    if (ret <= 0)
>          ret = -1;
>
>      virObjectUnref(cfg);
>

Good to change that, thanks, but the call to:
virBitmapNew(libxl_get_max_nodes(priv->ctx)) // in the same file
should be fixed as well, especially since virBitmapNew takes an
unsigned argument.  Could you modify that bit as well?

Martin
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