Re: [PATCH v2 2/3] xc/tmem: Unchecked return value

[Bob Liu <bob.liu@oracle.com>]

CC'd tools maintainers.

On 05/07/2014 02:30 PM, Bob Liu wrote:
> From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
> 
> 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.
> 
> v2:
> * superfluous braces and missing space (Andrew)
> * Add a comment why bailing out on xc_tmem_save_done is not needed
> 
> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
> Signed-off-by: Bob Liu <bob.liu@oracle.com>
> ---
>  tools/libxc/xc_domain_save.c |    6 ++++--
>  tools/libxc/xc_tmem.c        |    4 ++--
>  tools/libxc/xenctrl.h        |    2 +-
>  3 files changed, 7 insertions(+), 5 deletions(-)
> 
> diff --git a/tools/libxc/xc_domain_save.c b/tools/libxc/xc_domain_save.c
> index 71f9b59..856eaa5 100644
> --- a/tools/libxc/xc_domain_save.c
> +++ b/tools/libxc/xc_domain_save.c
> @@ -2107,8 +2107,10 @@ 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) )
> +        /* 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.");
>  
>      if ( live )
>      {
> diff --git a/tools/libxc/xc_tmem.c b/tools/libxc/xc_tmem.c
> index 6832bbe..250e438 100644
> --- a/tools/libxc/xc_tmem.c
> +++ b/tools/libxc/xc_tmem.c
> @@ -355,9 +355,9 @@ 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);
>  
> 

-- 
Regards,
-Bob