Fall back to /proc/cpuinfo if lscpu doesn't have CPU totals

https://github.com/chef/ohai/pull/1454 made `lscpu` the primary way
Ohai gathers CPU data, but the parser doesn't handle the output from a
Raspberry Pi 4 Cortex-A72. For example, an ARM cluster has the output
`Core(s) per cluster` instead of `Core(s) per socket`.

We should fall back to `/proc/cpuinfo` if we don't get reasonable data
back. It's not enough just to have `lscpu` output.

Closes https://github.com/chef/ohai/issues/1760

Signed-off-by: Stan Hu <stanhu@gmail.com>

1 files changed, 12 insertions, 4 deletions

diff --git a/lib/ohai/plugins/cpu.rb b/lib/ohai/plugins/cpu.rb
index e26a7ace..1d37c39f 100644
--- a/lib/ohai/plugins/cpu.rb
+++ b/lib/ohai/plugins/cpu.rb
@@ -344,15 +344,23 @@ Ohai.plugin(:CPU) do
     cpuinfo
   end
 
+  # Check if the `lscpu` data looks reasonable
+  def valid_lscpu?(lscpu)
+    return false if lscpu.empty?
+    return false if %i{total real cores}.any? { |key| lscpu[key].to_i == 0 }
+
+    true
+  end
+
   collect_data(:linux) do
     cpuinfo = parse_cpuinfo
     lscpu = parse_lscpu(cpuinfo)
 
-    # If we don't have any data from lscpu then get it from /proc/cpuinfo
-    if lscpu.empty?
-      cpu cpuinfo
-    else
+    # If we don't have any sensible data from lscpu then get it from /proc/cpuinfo
+    if valid_lscpu?(lscpu)
       cpu lscpu
+    else
+      cpu cpuinfo
     end
   end