1 files changed, 30 insertions, 3 deletions

diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c
index 4c0dccb756ad..3aef3062ff78 100644
--- a/kernel/perf_counter.c
+++ b/kernel/perf_counter.c
@@ -455,12 +455,37 @@ group_error:
         return -EAGAIN;
 }
 
+/*
+ * Return 1 for a software counter, 0 for a hardware counter
+ */
+static inline int is_software_counter(struct perf_counter *counter)
+{
+        return !counter->hw_event.raw && counter->hw_event.type < 0;
+}
+
+/*
+ * Return 1 for a group consisting entirely of software counters,
+ * 0 if the group contains any hardware counters.
+ */
+static int is_software_only_group(struct perf_counter *leader)
+{
+        struct perf_counter *counter;
+
+        if (!is_software_counter(leader))
+                return 0;
+        list_for_each_entry(counter, &leader->sibling_list, list_entry)
+                if (!is_software_counter(counter))
+                        return 0;
+        return 1;
+}
+
 static void
 __perf_counter_sched_in(struct perf_counter_context *ctx,
                         struct perf_cpu_context *cpuctx, int cpu)
 {
         struct perf_counter *counter;
         u64 flags;
+        int can_add_hw = 1;
 
         if (likely(!ctx->nr_counters))
                 return;
@@ -477,10 +502,12 @@ __perf_counter_sched_in(struct perf_counter_context *ctx,
 
                 /*
                  * If we scheduled in a group atomically and exclusively,
-                 * or if this group can't go on, break out:
+                 * or if this group can't go on, don't add any more
+                 * hardware counters.
                  */
-                if (group_sched_in(counter, cpuctx, ctx, cpu))
-                        break;
+                if (can_add_hw || is_software_only_group(counter))
+                        if (group_sched_in(counter, cpuctx, ctx, cpu))
+                                can_add_hw = 0;
         }
         hw_perf_restore(flags);
         spin_unlock(&ctx->lock);