1 files changed, 19 insertions, 2 deletions

diff --git a/include/linux/perf_counter.h b/include/linux/perf_counter.h
index 7ab8e5f96f5b..33ba9fe0a781 100644
--- a/include/linux/perf_counter.h
+++ b/include/linux/perf_counter.h
@@ -14,6 +14,7 @@
 #define _LINUX_PERF_COUNTER_H
 
 #include <asm/atomic.h>
+#include <asm/ioctl.h>
 
 #ifdef CONFIG_PERF_COUNTERS
 # include <asm/perf_counter.h>
@@ -95,6 +96,12 @@ struct perf_counter_hw_event {
 };
 
 /*
+ * Ioctls that can be done on a perf counter fd:
+ */
+#define PERF_COUNTER_IOC_ENABLE         _IO('$', 0)
+#define PERF_COUNTER_IOC_DISABLE        _IO('$', 1)
+
+/*
  * Kernel-internal data types:
  */
 
@@ -173,8 +180,10 @@ struct perf_counter {
         struct file                     *filp;
 
         struct perf_counter             *parent;
+        struct list_head                child_list;
+
         /*
-         * Protect attach/detach:
+         * Protect attach/detach and child_list:
          */
         struct mutex                    mutex;
 
@@ -199,13 +208,21 @@ struct perf_counter {
 struct perf_counter_context {
 #ifdef CONFIG_PERF_COUNTERS
         /*
-         * Protect the list of counters:
+         * Protect the states of the counters in the list,
+         * nr_active, and the list:
          */
         spinlock_t              lock;
+        /*
+         * Protect the list of counters.  Locking either mutex or lock
+         * is sufficient to ensure the list doesn't change; to change
+         * the list you need to lock both the mutex and the spinlock.
+         */
+        struct mutex            mutex;
 
         struct list_head        counter_list;
         int                     nr_counters;
         int                     nr_active;
+        int                     is_active;
         struct task_struct      *task;
 #endif
 };