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Subject[PATCH 4.18 041/168] tools/kvm_stat: fix handling of invalid paths in debugfs provider
Date
4.18-stable review patch.  If anyone has any objections, please let me know.

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

From: Stefan Raspl <stefan.raspl@de.ibm.com>

[ Upstream commit 617c66b9f236d20f11cecbb3f45e6d5675b2fae1 ]

When filtering by guest, kvm_stat displays garbage when the guest is
destroyed - see sample output below.
We add code to remove the invalid paths from the providers, so at least
no more garbage is displayed.
Here's a sample output to illustrate:

kvm statistics - pid 13986 (foo)

Event Total %Total CurAvg/s
diagnose_258 -2 0.0 0
deliver_program_interruption -3 0.0 0
diagnose_308 -4 0.0 0
halt_poll_invalid -91 0.0 -6
deliver_service_signal -244 0.0 -16
halt_successful_poll -250 0.1 -17
exit_pei -285 0.1 -19
exit_external_request -312 0.1 -21
diagnose_9c -328 0.1 -22
userspace_handled -713 0.1 -47
halt_attempted_poll -939 0.2 -62
deliver_emergency_signal -3126 0.6 -208
halt_wakeup -7199 1.5 -481
exit_wait_state -7379 1.5 -493
diagnose_500 -56499 11.5 -3757
exit_null -85491 17.4 -5685
diagnose_44 -133300 27.1 -8874
exit_instruction -195898 39.8 -13037
Total -492063

Signed-off-by: Stefan Raspl <raspl@linux.vnet.ibm.com>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
tools/kvm/kvm_stat/kvm_stat | 8 ++++++++
1 file changed, 8 insertions(+)

--- a/tools/kvm/kvm_stat/kvm_stat
+++ b/tools/kvm/kvm_stat/kvm_stat
@@ -766,6 +766,13 @@ class DebugfsProvider(Provider):
self.do_read = True
self.reset()

+ def _verify_paths(self):
+ """Remove invalid paths"""
+ for path in self.paths:
+ if not os.path.exists(os.path.join(PATH_DEBUGFS_KVM, path)):
+ self.paths.remove(path)
+ continue
+
def read(self, reset=0, by_guest=0):
"""Returns a dict with format:'file name / field -> current value'.

@@ -780,6 +787,7 @@ class DebugfsProvider(Provider):
# If no debugfs filtering support is available, then don't read.
if not self.do_read:
return results
+ self._verify_paths()

paths = self.paths
if self._pid == 0:

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