Re: [PATCH 2/4] xc/tmem: Unchecked return value (v2).

[Andrew Cooper <andrew.cooper3@citrix.com>]

On 30/04/2014 21:29, Konrad Rzeszutek Wilk wrote:
> CID 1055045 complains that the return value needs checking.
>
> The tmem op is a flush call and there is no expectation
> right now of any return besides zero. But just in case
> this changes lets blow up.
>
> CC: Bob Liu <bob.liu@oracle.com>
> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
> [v2: Add a comment why bailing out on xc_tmem_save_done is not needed]
> ---
>  tools/libxc/xc_domain_save.c | 8 ++++++--
>  tools/libxc/xc_tmem.c        | 4 ++--
>  tools/libxc/xenctrl.h        | 2 +-
>  3 files changed, 9 insertions(+), 5 deletions(-)
>
> diff --git a/tools/libxc/xc_domain_save.c b/tools/libxc/xc_domain_save.c
> index 71f9b59..b04e387 100644
> --- a/tools/libxc/xc_domain_save.c
> +++ b/tools/libxc/xc_domain_save.c
> @@ -2107,8 +2107,12 @@ int xc_domain_save(xc_interface *xch, int io_fd, uint32_t dom, uint32_t max_iter
>          goto copypages;
>      }
>  
> -    if ( tmem_saved != 0 && live )
> -        xc_tmem_save_done(xch, dom);
> +    if ( tmem_saved != 0 && live && xc_tmem_save_done(xch, dom))

Missing space before final bracket

> +    {
> +        /* N.B. No need to bail out - we leak memory, but that is all assigned
> +         * to the zombie guest. */
> +       DPRINTF("Warning - failed to flush tmem on originating server.");
> +    }

And superfluous braces.

Functionally however, Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>

~Andrew

>  
>      if ( live )
>      {
> diff --git a/tools/libxc/xc_tmem.c b/tools/libxc/xc_tmem.c
> index 12fa105..6e01a6a 100644
> --- a/tools/libxc/xc_tmem.c
> +++ b/tools/libxc/xc_tmem.c
> @@ -356,9 +356,9 @@ int xc_tmem_save_extra(xc_interface *xch, int dom, int io_fd, int field_marker)
>  }
>  
>  /* only called for live migration */
> -void xc_tmem_save_done(xc_interface *xch, int dom)
> +int xc_tmem_save_done(xc_interface *xch, int dom)
>  {
> -    xc_tmem_control(xch,0,TMEMC_SAVE_END,dom,0,0,0,NULL);
> +    return xc_tmem_control(xch,0,TMEMC_SAVE_END,dom,0,0,0,NULL);
>  }
>  
>  /* restore routines */
> diff --git a/tools/libxc/xenctrl.h b/tools/libxc/xenctrl.h
> index 02129f7..23630a7 100644
> --- a/tools/libxc/xenctrl.h
> +++ b/tools/libxc/xenctrl.h
> @@ -2011,7 +2011,7 @@ int xc_tmem_control(xc_interface *xch,
>  int xc_tmem_auth(xc_interface *xch, int cli_id, char *uuid_str, int arg1);
>  int xc_tmem_save(xc_interface *xch, int dom, int live, int fd, int field_marker);
>  int xc_tmem_save_extra(xc_interface *xch, int dom, int fd, int field_marker);
> -void xc_tmem_save_done(xc_interface *xch, int dom);
> +int xc_tmem_save_done(xc_interface *xch, int dom);
>  int xc_tmem_restore(xc_interface *xch, int dom, int fd);
>  int xc_tmem_restore_extra(xc_interface *xch, int dom, int fd);
>