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-rw-r--r--kernel/perf_counter.c44
1 files changed, 18 insertions, 26 deletions
diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c
index e26d2fcfa32..3dd4339589a 100644
--- a/kernel/perf_counter.c
+++ b/kernel/perf_counter.c
@@ -3444,40 +3444,32 @@ static void perf_swcounter_add(struct perf_counter *counter, u64 nr,
static int perf_swcounter_is_counting(struct perf_counter *counter)
{
- struct perf_counter_context *ctx;
- unsigned long flags;
- int count;
-
+ /*
+ * The counter is active, we're good!
+ */
if (counter->state == PERF_COUNTER_STATE_ACTIVE)
return 1;
+ /*
+ * The counter is off/error, not counting.
+ */
if (counter->state != PERF_COUNTER_STATE_INACTIVE)
return 0;
/*
- * If the counter is inactive, it could be just because
- * its task is scheduled out, or because it's in a group
- * which could not go on the PMU. We want to count in
- * the first case but not the second. If the context is
- * currently active then an inactive software counter must
- * be the second case. If it's not currently active then
- * we need to know whether the counter was active when the
- * context was last active, which we can determine by
- * comparing counter->tstamp_stopped with ctx->time.
- *
- * We are within an RCU read-side critical section,
- * which protects the existence of *ctx.
+ * The counter is inactive, if the context is active
+ * we're part of a group that didn't make it on the 'pmu',
+ * not counting.
*/
- ctx = counter->ctx;
- spin_lock_irqsave(&ctx->lock, flags);
- count = 1;
- /* Re-check state now we have the lock */
- if (counter->state < PERF_COUNTER_STATE_INACTIVE ||
- counter->ctx->is_active ||
- counter->tstamp_stopped < ctx->time)
- count = 0;
- spin_unlock_irqrestore(&ctx->lock, flags);
- return count;
+ if (counter->ctx->is_active)
+ return 0;
+
+ /*
+ * We're inactive and the context is too, this means the
+ * task is scheduled out, we're counting events that happen
+ * to us, like migration events.
+ */
+ return 1;
}
static int perf_swcounter_match(struct perf_counter *counter,