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authorLike Xu <like.xu@linux.intel.com>2019-10-27 18:52:39 +0800
committerPaolo Bonzini <pbonzini@redhat.com>2019-11-15 11:44:07 +0100
commit52ba4b0b99770e892f43da1238f437155acb8b58 (patch)
tree18ee181729eb2cea9841a2bffb72d3da055ccabd /kernel
parent3ca270fc9edb258d5bfa271bcf851614e9e6e7d4 (diff)
perf/core: Provide a kernel-internal interface to pause perf_event
Exporting perf_event_pause() as an external accessor for kernel users (such as KVM) who may do both disable perf_event and read count with just one time to hold perf_event_ctx_lock. Also the value could be reset optionally. Suggested-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Like Xu <like.xu@linux.intel.com> Acked-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/events/core.c18
1 files changed, 18 insertions, 0 deletions
diff --git a/kernel/events/core.c b/kernel/events/core.c
index e1b83d2731da..fc9f5ebf4849 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -5029,6 +5029,24 @@ static void _perf_event_reset(struct perf_event *event)
perf_event_update_userpage(event);
}
+/* Assume it's not an event with inherit set. */
+u64 perf_event_pause(struct perf_event *event, bool reset)
+{
+ struct perf_event_context *ctx;
+ u64 count;
+
+ ctx = perf_event_ctx_lock(event);
+ WARN_ON_ONCE(event->attr.inherit);
+ _perf_event_disable(event);
+ count = local64_read(&event->count);
+ if (reset)
+ local64_set(&event->count, 0);
+ perf_event_ctx_unlock(event, ctx);
+
+ return count;
+}
+EXPORT_SYMBOL_GPL(perf_event_pause);
+
/*
* Holding the top-level event's child_mutex means that any
* descendant process that has inherited this event will block