tracing: Fix typo in prof_sysexit_enable()

[safe/jmp/linux-2.6] / kernel / trace / trace_event_profile.c

diff --git a/kernel/trace/trace_event_profile.c b/kernel/trace/trace_event_profile.c
index 7bf2ad6..9e25573 100644 (file)
--- a/kernel/trace/trace_event_profile.c
+++ b/kernel/trace/trace_event_profile.c
@@ -5,26 +5,118 @@
  *
  */
 
+#include <linux/module.h>
 #include "trace.h"
 
+
+char *perf_trace_buf;
+EXPORT_SYMBOL_GPL(perf_trace_buf);
+
+char *perf_trace_buf_nmi;
+EXPORT_SYMBOL_GPL(perf_trace_buf_nmi);
+
+typedef typeof(char [FTRACE_MAX_PROFILE_SIZE]) perf_trace_t ;
+
+/* Count the events in use (per event id, not per instance) */
+static int     total_profile_count;
+
+static int ftrace_profile_enable_event(struct ftrace_event_call *event)
+{
+       char *buf;
+       int ret = -ENOMEM;
+
+       if (event->profile_count++ > 0)
+               return 0;
+
+       if (!total_profile_count) {
+               buf = (char *)alloc_percpu(perf_trace_t);
+               if (!buf)
+                       goto fail_buf;
+
+               rcu_assign_pointer(perf_trace_buf, buf);
+
+               buf = (char *)alloc_percpu(perf_trace_t);
+               if (!buf)
+                       goto fail_buf_nmi;
+
+               rcu_assign_pointer(perf_trace_buf_nmi, buf);
+       }
+
+       ret = event->profile_enable(event);
+       if (!ret) {
+               total_profile_count++;
+               return 0;
+       }
+
+fail_buf_nmi:
+       if (!total_profile_count) {
+               free_percpu(perf_trace_buf_nmi);
+               free_percpu(perf_trace_buf);
+               perf_trace_buf_nmi = NULL;
+               perf_trace_buf = NULL;
+       }
+fail_buf:
+       event->profile_count--;
+
+       return ret;
+}
+
 int ftrace_profile_enable(int event_id)
 {
        struct ftrace_event_call *event;
+       int ret = -EINVAL;
 
+       mutex_lock(&event_mutex);
        list_for_each_entry(event, &ftrace_events, list) {
-               if (event->id == event_id)
-                       return event->profile_enable(event);
+               if (event->id == event_id && event->profile_enable &&
+                   try_module_get(event->mod)) {
+                       ret = ftrace_profile_enable_event(event);
+                       break;
+               }
        }
+       mutex_unlock(&event_mutex);
+
+       return ret;
+}
+
+static void ftrace_profile_disable_event(struct ftrace_event_call *event)
+{
+       char *buf, *nmi_buf;
+
+       if (--event->profile_count > 0)
+               return;
+
+       event->profile_disable(event);
+
+       if (!--total_profile_count) {
+               buf = perf_trace_buf;
+               rcu_assign_pointer(perf_trace_buf, NULL);
 
-       return -EINVAL;
+               nmi_buf = perf_trace_buf_nmi;
+               rcu_assign_pointer(perf_trace_buf_nmi, NULL);
+
+               /*
+                * Ensure every events in profiling have finished before
+                * releasing the buffers
+                */
+               synchronize_sched();
+
+               free_percpu(buf);
+               free_percpu(nmi_buf);
+       }
 }
 
 void ftrace_profile_disable(int event_id)
 {
        struct ftrace_event_call *event;
 
+       mutex_lock(&event_mutex);
        list_for_each_entry(event, &ftrace_events, list) {
-               if (event->id == event_id)
-                       return event->profile_disable(event);
+               if (event->id == event_id) {
+                       ftrace_profile_disable_event(event);
+                       module_put(event->mod);
+                       break;
+               }
        }
+       mutex_unlock(&event_mutex);
 }