Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next

[pandora-kernel.git] / kernel / events / core.c

diff --git a/kernel/events/core.c b/kernel/events/core.c
index ae16867..e818389 100644 (file)
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -3222,6 +3222,59 @@ static inline u64 perf_event_count(struct perf_event *event)
        return __perf_event_count(event);
 }
 
+/*
+ * NMI-safe method to read a local event, that is an event that
+ * is:
+ *   - either for the current task, or for this CPU
+ *   - does not have inherit set, for inherited task events
+ *     will not be local and we cannot read them atomically
+ *   - must not have a pmu::count method
+ */
+u64 perf_event_read_local(struct perf_event *event)
+{
+       unsigned long flags;
+       u64 val;
+
+       /*
+        * Disabling interrupts avoids all counter scheduling (context
+        * switches, timer based rotation and IPIs).
+        */
+       local_irq_save(flags);
+
+       /* If this is a per-task event, it must be for current */
+       WARN_ON_ONCE((event->attach_state & PERF_ATTACH_TASK) &&
+                    event->hw.target != current);
+
+       /* If this is a per-CPU event, it must be for this CPU */
+       WARN_ON_ONCE(!(event->attach_state & PERF_ATTACH_TASK) &&
+                    event->cpu != smp_processor_id());
+
+       /*
+        * It must not be an event with inherit set, we cannot read
+        * all child counters from atomic context.
+        */
+       WARN_ON_ONCE(event->attr.inherit);
+
+       /*
+        * It must not have a pmu::count method, those are not
+        * NMI safe.
+        */
+       WARN_ON_ONCE(event->pmu->count);
+
+       /*
+        * If the event is currently on this CPU, its either a per-task event,
+        * or local to this CPU. Furthermore it means its ACTIVE (otherwise
+        * oncpu == -1).
+        */
+       if (event->oncpu == smp_processor_id())
+               event->pmu->read(event);
+
+       val = local64_read(&event->count);
+       local_irq_restore(flags);
+
+       return val;
+}
+
 static u64 perf_event_read(struct perf_event *event)
 {
        /*
@@ -8718,6 +8771,31 @@ void perf_event_delayed_put(struct task_struct *task)
                WARN_ON_ONCE(task->perf_event_ctxp[ctxn]);
 }
 
+struct perf_event *perf_event_get(unsigned int fd)
+{
+       int err;
+       struct fd f;
+       struct perf_event *event;
+
+       err = perf_fget_light(fd, &f);
+       if (err)
+               return ERR_PTR(err);
+
+       event = f.file->private_data;
+       atomic_long_inc(&event->refcount);
+       fdput(f);
+
+       return event;
+}
+
+const struct perf_event_attr *perf_event_attrs(struct perf_event *event)
+{
+       if (!event)
+               return ERR_PTR(-EINVAL);
+
+       return &event->attr;
+}
+
 /*
  * inherit a event from parent task to child task:
  */