tools/kvm_stat: fix fields filter for child events

From: Stefan Raspl <[email protected]>

The fields filter would not work with child fields, as the respective parents would not be included. No parents displayed == no childs displayed. To reproduce, run on s390 (would work on other platforms, too, but would require a different filter name):
- Run 'kvm_stat -d'
- Press 'f'
- Enter 'instruct'
Notice that events like instruction_diag_44 or instruction_diag_500 are not displayed - the output remains empty.
With this patch, we will filter by matching events and their parents. However, consider the following example where we filter by instruction_diag_44:

kvm statistics - summary
regex filter: instruction_diag_44
Event Total %Total CurAvg/s

   exit_instruction                                276  100.0       12
     instruction_diag_44                           256   92.8       11
   Total                                           276              12

Note that the parent ('exit_instruction') displays the total events, but the childs listed do not match its total (256 instead of 276). This is intended (since we're filtering all but one child), but might be confusing on first sight.

Signed-off-by Stefan Raspl <[email protected]>

---
 tools/kvm/kvm_stat/kvm_stat     | 16 ++++++++++++----
 tools/kvm/kvm_stat/kvm_stat.txt |  2 ++
 2 files changed, 14 insertions(+), 4 deletions(-)

tools/kvm/kvm_stat/kvm_stat +12 -4

index 2ed395b817cb..bc508dae286c 100755
@@ -575,8 +575,12 @@ class TracepointProvider(Provider):
     def update_fields(self, fields_filter):
         """Refresh fields, applying fields_filter"""
         self.fields = [field for field in self._get_available_fields()
-                       if self.is_field_wanted(fields_filter, field) or
-                       ARCH.tracepoint_is_child(field)]
+                       if self.is_field_wanted(fields_filter, field)]
+        # add parents for child fields - otherwise we won't see any output!
+        for field in self._fields:
+            parent = ARCH.tracepoint_is_child(field)
+            if (parent and parent not in self._fields):
+                self.fields.append(parent)
 
     @staticmethod
     def _get_online_cpus():

@@ -735,8 +739,12 @@ class DebugfsProvider(Provider):
     def update_fields(self, fields_filter):
         """Refresh fields, applying fields_filter"""
         self._fields = [field for field in self._get_available_fields()
-                        if self.is_field_wanted(fields_filter, field) or
-                        ARCH.debugfs_is_child(field)]
+                        if self.is_field_wanted(fields_filter, field)]
+        # add parents for child fields - otherwise we won't see any output!
+        for field in self._fields:
+            parent = ARCH.debugfs_is_child(field)
+            if (parent and parent not in self._fields):
+                self.fields.append(parent)
 
     @property
     def fields(self):

tools/kvm/kvm_stat/kvm_stat.txt +0 -0

index 0811d860fe75..c057ba52364e 100644