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| author | Dean Deng <deandeng@google.com> | 2020-09-27 15:31:43 -0700 |
|---|---|---|
| committer | gVisor bot <gvisor-bot@google.com> | 2020-09-27 15:33:51 -0700 |
| commit | 2a60f9229166effac64653be4f46683ea1a0cd87 (patch) | |
| tree | 96264a77d7b541a884e41bb85efaadcb23f4d4eb /pkg/sentry/kernel | |
| parent | a376a0baf362506549fcc58861465fa89ed33f7f (diff) | |
Clean up kcov.
Previously, we did not check the kcov mode when performing task work. As a
result, disabling kcov did not do anything.
Also avoid expensive atomic RMW when consuming coverage data. We don't need the
swap if the value is already zero (which is most of the time), and it is ok if
there are slight inconsistencies due to a race between coverage data generation
(incrementing the value) and consumption (reading a nonzero value and writing
zero).
PiperOrigin-RevId: 334049207
Diffstat (limited to 'pkg/sentry/kernel')
| -rw-r--r-- | pkg/sentry/kernel/kcov.go | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/pkg/sentry/kernel/kcov.go b/pkg/sentry/kernel/kcov.go index aad63aa99..d3e76ca7b 100644 --- a/pkg/sentry/kernel/kcov.go +++ b/pkg/sentry/kernel/kcov.go @@ -89,6 +89,10 @@ func (kcov *Kcov) TaskWork(t *Task) { kcov.mu.Lock() defer kcov.mu.Unlock() + if kcov.mode != linux.KCOV_TRACE_PC { + return + } + rw := &kcovReadWriter{ mf: kcov.mfp.MemoryFile(), fr: kcov.mappable.FileRange(), |