Re: [PATCH v1 3/3] xen-livepatch: If hypervisor is not compiled with Livepatching

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

On Thu, Sep 22, 2016 at 08:25:33AM +0100, Ross Lagerwall wrote:
> On 09/21/2016 08:20 PM, Konrad Rzeszutek Wilk wrote:
> > . print a better error code.
> > 
> > Reported-by: Andrew Cooper <andrew.cooper3@citrix.com>
> > Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
> > ---
> >  tools/misc/xen-livepatch.c | 7 +++++--
> >  1 file changed, 5 insertions(+), 2 deletions(-)
> > 
> > diff --git a/tools/misc/xen-livepatch.c b/tools/misc/xen-livepatch.c
> > index 2de04c0..f11e71f07f 100644
> > --- a/tools/misc/xen-livepatch.c
> > +++ b/tools/misc/xen-livepatch.c
> > @@ -100,8 +100,11 @@ static int list_func(int argc, char *argv[])
> >          rc = xc_livepatch_list(xch, MAX_LEN, idx, info, name, len, &done, &left);
> >          if ( rc )
> >          {
> > -            fprintf(stderr, "Failed to list %d/%d: %d(%s)!\n",
> > -                    idx, left, errno, strerror(errno));
> > +            if ( errno == ENOSYS )
> > +                fprintf(stderr, "Hypervisor compiled without Xen Livepatching!\n");
> > +            else
> > +                fprintf(stderr, "Failed to list %d/%d: %d(%s)!\n",
> > +                        idx, left, errno, strerror(errno));
> >              break;
> >          }
> >          if ( !idx )
> > 
> 
> You should save errno since you have an fprintf before you check it.

I am missing something.

Why would fprintf mess up 'errno' ?
> 
> Also, it would be good to do the same check for the first xc_livepatch_get
> in action_func() and for the xc_livepatch_upload in upload_func.

<nods>
> 
> -- 
> Ross Lagerwall

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