[PATCH 4.18 042/168] tools/kvm_stat: fix updates for dead guests

[Greg Kroah-Hartman]

4.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Stefan Raspl <stefan.raspl@xxxxxxxxxx>

[ Upstream commit 710ab11ad9329d2d4b044405e328c994b19a2aa9 ]

With pid filtering active, when a guest is removed e.g. via virsh shutdown,
successive updates produce garbage.
Therefore, we add code to detect this case and prevent further body updates.
Note that when displaying the help dialog via 'h' in this case, once we exit
we're stuck with the 'Collecting data...' message till we remove the filter.

Signed-off-by: Stefan Raspl <raspl@xxxxxxxxxxxxx>
Signed-off-by: Radim KrÄmÃÅ <rkrcmar@xxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 tools/kvm/kvm_stat/kvm_stat |   11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

--- a/tools/kvm/kvm_stat/kvm_stat
+++ b/tools/kvm/kvm_stat/kvm_stat
@@ -1170,6 +1170,9 @@ class Tui(object):
 
             return sorted_items
 
+        if not self._is_running_guest(self.stats.pid_filter):
+            # leave final data on screen
+            return
         row = 3
         self.screen.move(row, 0)
         self.screen.clrtobot()
@@ -1327,6 +1330,12 @@ class Tui(object):
                 msg = '"' + str(val) + '": Invalid value'
         self._refresh_header()
 
+    def _is_running_guest(self, pid):
+        """Check if pid is still a running process."""
+        if not pid:
+            return True
+        return os.path.isdir(os.path.join('/proc/', str(pid)))
+
     def _show_vm_selection_by_guest(self):
         """Draws guest selection mask.
 
@@ -1354,7 +1363,7 @@ class Tui(object):
             if not guest or guest == '0':
                 break
             if guest.isdigit():
-                if not os.path.isdir(os.path.join('/proc/', guest)):
+                if not self._is_running_guest(guest):
                     msg = '"' + guest + '": Not a running process'
                     continue
                 pid = int(guest)