[PATCH] util: virhostcpu: Fail when fetching CPU Stats for invalid cpu

[Michal Prívozník]

On 21. 2. 2020 19:10, Mauro S. M. Rodrigues wrote:
> virHostCPUGetStatsLinux walks through every cpu in /proc/stat until it
> finds cpu%cpuNum that matches with the requested cpu.
> If none is found it logs the error but it should return -1, instead of 0.
> Otherwise virsh nodecpustats --cpu <invalid cpu number> and API bindings
> don't fail properly, printing a blank line instead of an error message.
> 
> This patch also includes an additional test for virhostcputest to avoid
> this regression to happen again in the future.
> 
> Reported-by: Satheesh Rajendran <satheera at in.ibm.com>
> Signed-off-by: Mauro S. M. Rodrigues <maurosr at linux.vnet.ibm.com>
> ---
>  src/util/virhostcpu.c  | 2 +-
>  tests/virhostcputest.c | 9 ++++++---
>  2 files changed, 7 insertions(+), 4 deletions(-)
> 
> diff --git a/src/util/virhostcpu.c b/src/util/virhostcpu.c
> index 81293eea8c..20c8d0ce6c 100644
> --- a/src/util/virhostcpu.c
> +++ b/src/util/virhostcpu.c
> @@ -847,7 +847,7 @@ virHostCPUGetStatsLinux(FILE *procstat,
>                          _("Invalid cpuNum in %s"),
>                          __FUNCTION__);
>  
> -    return 0;
> +    return -1;
>  }

Oops, yes. This was introduced by 93af79fba3fd75a8df6b7ca608719dd97f9511a0.

>  
>  
> diff --git a/tests/virhostcputest.c b/tests/virhostcputest.c
> index 7865b61578..2f569d8bd4 100644
> --- a/tests/virhostcputest.c
> +++ b/tests/virhostcputest.c
> @@ -258,14 +258,17 @@ mymain(void)
>          if (virTestRun(nodeData[i].testName, linuxTestHostCPU, &nodeData[i]) != 0)
>              ret = -1;
>  
> -# define DO_TEST_CPU_STATS(name, ncpus) \
> +# define DO_TEST_CPU_STATS(name, ncpus, shouldFail) \
>      do { \
>          static struct nodeCPUStatsData data = { name, ncpus }; \
> -        if (virTestRun("CPU stats " name, linuxTestNodeCPUStats, &data) < 0) \
> +        if ((virTestRun("CPU stats " name, \
> +			linuxTestNodeCPUStats, \
> +			&data) < 0) != shouldFail) \

We do it slightly differently. We pass shouldFail to the callback and
let it fix its retval so that virTestRun() interprets it properly.

>              ret = -1; \
>      } while (0)
>  
> -    DO_TEST_CPU_STATS("24cpu", 24);
> +    DO_TEST_CPU_STATS("24cpu", 24, false);
> +    DO_TEST_CPU_STATS("24cpu", 25, true);
>  
>      return ret == 0 ? EXIT_SUCCESS : EXIT_FAILURE;
>  }
> 

I'm fixing the test, adding the referenced commit into the commit
message and pushing.

Reviewed-by: Michal Privoznik <mprivozn at redhat.com>

Congratulations on your first libvirt contribution!

Michal