[libvirt] [PATCH] Fix scheduler support check

[Erik Skultety]

On Fri, Nov 18, 2016 at 10:34:47AM +0100, Martin Kletzander wrote:
> Commit 94cc577807ba tried fixing build on systems that did not have
> SCHED_BATCH or SCHED_IDLE defined.  But instead of changing it to
> conditional support, it rather completely disabled the support for
> setting any scheduler.  Since then, such old systems are not
> supported, but rather than reverting that commit, let's change that to
> the conditional support.  That way any addition to the list of
> schedulers can follow the same style so that we're consistent in the
> future.
> 
> Signed-off-by: Martin Kletzander <mkletzan at redhat.com>
> ---
> 
> Notes:
>     Of course there are various ways how to address that, I went with
>     case.  Also defining undefined SCHED_* to -1 makes some gnulib
>     syntax-check go haywire.
> 
>  src/util/virprocess.c | 17 ++++++++++++++++-
>  1 file changed, 16 insertions(+), 1 deletion(-)
> 
> diff --git a/src/util/virprocess.c b/src/util/virprocess.c
> index 718c4a2664e1..39d6b30c40f2 100644
> --- a/src/util/virprocess.c
> +++ b/src/util/virprocess.c
> @@ -1183,7 +1183,7 @@ virProcessExitWithStatus(int status)
>      exit(value);
>  }
> 
> -#if HAVE_SCHED_SETSCHEDULER && defined(SCHED_BATCH) && defined(SCHED_IDLE)
> +#if HAVE_SCHED_SETSCHEDULER
> 
>  static int
>  virProcessSchedTranslatePolicy(virProcessSchedPolicy policy)
> @@ -1196,10 +1196,18 @@ virProcessSchedTranslatePolicy(virProcessSchedPolicy policy)
>          return SCHED_BATCH;
> 
>      case VIR_PROC_POLICY_IDLE:
> +# ifdef SCHED_IDLE
>          return SCHED_IDLE;
> +# else
> +        return -1;
> +# endif
> 
>      case VIR_PROC_POLICY_FIFO:
> +# ifdef SCHED_FIFO
>          return SCHED_FIFO;
> +# else
> +        return -1;
> +# endif
> 

Didn't you by any chance mean to make SCHED_BATCH conditional instead of
SCHED_FIFO which might have probably been part of the kernel since forever (at
least man 7 sched doesn't say anything about when it was added).

ACK with that fixed.

Erik

>      case VIR_PROC_POLICY_RR:
>          return SCHED_RR;
> @@ -1225,6 +1233,13 @@ virProcessSetScheduler(pid_t pid,
>      if (!policy)
>          return 0;
> 
> +    if (pol < 0) {
> +        virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
> +                       _("Scheduler '%s' is not supported on this platform"),
> +                       virProcessSchedPolicyTypeToString(policy));
> +        return -1;
> +    }
> +
>      if (pol == SCHED_FIFO || pol == SCHED_RR) {
>          int min = 0;
>          int max = 0;
> -- 
> 2.10.2
> 
> --
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> libvir-list at redhat.com
> https://www.redhat.com/mailman/listinfo/libvir-list
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