ftrace, perf: Add open/close tracepoint perf registration actions

Adding TRACE_REG_PERF_OPEN and TRACE_REG_PERF_CLOSE to differentiate
register/unregister from open/close actions.

The register/unregister actions are invoked for the first/last
tracepoint user when opening/closing the event.

The open/close actions are invoked for each tracepoint user when
opening/closing the event.

Link: http://lkml.kernel.org/r/1329317514-8131-3-git-send-email-jolsa@redhat.com

Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 75 insertions, 41 deletions

diff --git a/kernel/trace/trace_event_perf.c b/kernel/trace/trace_event_perf.c
index 19a359d5e6d5..0cfcc37f63de 100644
--- a/kernel/trace/trace_event_perf.c
+++ b/kernel/trace/trace_event_perf.c
@@ -44,23 +44,17 @@ static int perf_trace_event_perm(struct ftrace_event_call *tp_event,
         return 0;
 }
 
-static int perf_trace_event_init(struct ftrace_event_call *tp_event,
-                                 struct perf_event *p_event)
+static int perf_trace_event_reg(struct ftrace_event_call *tp_event,
+                                struct perf_event *p_event)
 {
         struct hlist_head __percpu *list;
-        int ret;
+        int ret = -ENOMEM;
         int cpu;
 
-        ret = perf_trace_event_perm(tp_event, p_event);
-        if (ret)
-                return ret;
-
         p_event->tp_event = tp_event;
         if (tp_event->perf_refcount++ > 0)
                 return 0;
 
-        ret = -ENOMEM;
-
         list = alloc_percpu(struct hlist_head);
         if (!list)
                 goto fail;
@@ -83,7 +77,7 @@ static int perf_trace_event_init(struct ftrace_event_call *tp_event,
                 }
         }
 
-        ret = tp_event->class->reg(tp_event, TRACE_REG_PERF_REGISTER);
+        ret = tp_event->class->reg(tp_event, TRACE_REG_PERF_REGISTER, NULL);
         if (ret)
                 goto fail;
 
@@ -108,6 +102,69 @@ fail:
         return ret;
 }
 
+static void perf_trace_event_unreg(struct perf_event *p_event)
+{
+        struct ftrace_event_call *tp_event = p_event->tp_event;
+        int i;
+
+        if (--tp_event->perf_refcount > 0)
+                goto out;
+
+        tp_event->class->reg(tp_event, TRACE_REG_PERF_UNREGISTER, NULL);
+
+        /*
+         * Ensure our callback won't be called anymore. The buffers
+         * will be freed after that.
+         */
+        tracepoint_synchronize_unregister();
+
+        free_percpu(tp_event->perf_events);
+        tp_event->perf_events = NULL;
+
+        if (!--total_ref_count) {
+                for (i = 0; i < PERF_NR_CONTEXTS; i++) {
+                        free_percpu(perf_trace_buf[i]);
+                        perf_trace_buf[i] = NULL;
+                }
+        }
+out:
+        module_put(tp_event->mod);
+}
+
+static int perf_trace_event_open(struct perf_event *p_event)
+{
+        struct ftrace_event_call *tp_event = p_event->tp_event;
+        return tp_event->class->reg(tp_event, TRACE_REG_PERF_OPEN, p_event);
+}
+
+static void perf_trace_event_close(struct perf_event *p_event)
+{
+        struct ftrace_event_call *tp_event = p_event->tp_event;
+        tp_event->class->reg(tp_event, TRACE_REG_PERF_CLOSE, p_event);
+}
+
+static int perf_trace_event_init(struct ftrace_event_call *tp_event,
+                                 struct perf_event *p_event)
+{
+        int ret;
+
+        ret = perf_trace_event_perm(tp_event, p_event);
+        if (ret)
+                return ret;
+
+        ret = perf_trace_event_reg(tp_event, p_event);
+        if (ret)
+                return ret;
+
+        ret = perf_trace_event_open(p_event);
+        if (ret) {
+                perf_trace_event_unreg(p_event);
+                return ret;
+        }
+
+        return 0;
+}
+
 int perf_trace_init(struct perf_event *p_event)
 {
         struct ftrace_event_call *tp_event;
@@ -130,6 +187,14 @@ int perf_trace_init(struct perf_event *p_event)
         return ret;
 }
 
+void perf_trace_destroy(struct perf_event *p_event)
+{
+        mutex_lock(&event_mutex);
+        perf_trace_event_close(p_event);
+        perf_trace_event_unreg(p_event);
+        mutex_unlock(&event_mutex);
+}
+
 int perf_trace_add(struct perf_event *p_event, int flags)
 {
         struct ftrace_event_call *tp_event = p_event->tp_event;
@@ -154,37 +219,6 @@ void perf_trace_del(struct perf_event *p_event, int flags)
         hlist_del_rcu(&p_event->hlist_entry);
 }
 
-void perf_trace_destroy(struct perf_event *p_event)
-{
-        struct ftrace_event_call *tp_event = p_event->tp_event;
-        int i;
-
-        mutex_lock(&event_mutex);
-        if (--tp_event->perf_refcount > 0)
-                goto out;
-
-        tp_event->class->reg(tp_event, TRACE_REG_PERF_UNREGISTER);
-
-        /*
-         * Ensure our callback won't be called anymore. The buffers
-         * will be freed after that.
-         */
-        tracepoint_synchronize_unregister();
-
-        free_percpu(tp_event->perf_events);
-        tp_event->perf_events = NULL;
-
-        if (!--total_ref_count) {
-                for (i = 0; i < PERF_NR_CONTEXTS; i++) {
-                        free_percpu(perf_trace_buf[i]);
-                        perf_trace_buf[i] = NULL;
-                }
-        }
-out:
-        module_put(tp_event->mod);
-        mutex_unlock(&event_mutex);
-}
-
 __kprobes void *perf_trace_buf_prepare(int size, unsigned short type,
                                        struct pt_regs *regs, int *rctxp)
 {