perf/core: Correct event creation with PERF_FORMAT_GROUP

[karo-tx-linux.git] / kernel / events / core.c

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 3de0b98c441465976121ec6fcdbba00c7e0d8a28..407dad6cf89ac55e221c3a4519ed2c25c1241dc7 100644 (file)
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -5729,9 +5729,6 @@ static void perf_output_read_one(struct perf_output_handle *handle,
        __output_copy(handle, values, n * sizeof(u64));
 }
 
-/*
- * XXX PERF_FORMAT_GROUP vs inherited events seems difficult.
- */
 static void perf_output_read_group(struct perf_output_handle *handle,
                            struct perf_event *event,
                            u64 enabled, u64 running)
@@ -5776,6 +5773,13 @@ static void perf_output_read_group(struct perf_output_handle *handle,
 #define PERF_FORMAT_TOTAL_TIMES (PERF_FORMAT_TOTAL_TIME_ENABLED|\
                                 PERF_FORMAT_TOTAL_TIME_RUNNING)
 
+/*
+ * XXX PERF_SAMPLE_READ vs inherited events seems difficult.
+ *
+ * The problem is that its both hard and excessively expensive to iterate the
+ * child list, not to mention that its impossible to IPI the children running
+ * on another CPU, from interrupt/NMI context.
+ */
 static void perf_output_read(struct perf_output_handle *handle,
                             struct perf_event *event)
 {
@@ -9462,9 +9466,10 @@ perf_event_alloc(struct perf_event_attr *attr, int cpu,
        local64_set(&hwc->period_left, hwc->sample_period);
 
        /*
-        * we currently do not support PERF_FORMAT_GROUP on inherited events
+        * We currently do not support PERF_SAMPLE_READ on inherited events.
+        * See perf_output_read().
         */
-       if (attr->inherit && (attr->read_format & PERF_FORMAT_GROUP))
+       if (attr->inherit && (attr->sample_type & PERF_SAMPLE_READ))
                goto err_ns;
 
        if (!has_branch_stack(event))