2 * trace event based perf counter profiling
4 * Copyright (C) 2009 Red Hat Inc, Peter Zijlstra <pzijlstr@redhat.com>
8 #include <linux/module.h>
12 * We can't use a size but a type in alloc_percpu()
13 * So let's create a dummy type that matches the desired size
15 typedef struct {char buf[FTRACE_MAX_PROFILE_SIZE];} profile_buf_t;
17 char *trace_profile_buf;
18 EXPORT_SYMBOL_GPL(trace_profile_buf);
20 char *trace_profile_buf_nmi;
21 EXPORT_SYMBOL_GPL(trace_profile_buf_nmi);
23 /* Count the events in use (per event id, not per instance) */
24 static int total_profile_count;
26 static int ftrace_profile_enable_event(struct ftrace_event_call *event)
31 if (atomic_inc_return(&event->profile_count))
34 if (!total_profile_count++) {
35 buf = (char *)alloc_percpu(profile_buf_t);
39 rcu_assign_pointer(trace_profile_buf, buf);
41 buf = (char *)alloc_percpu(profile_buf_t);
45 rcu_assign_pointer(trace_profile_buf_nmi, buf);
48 ret = event->profile_enable();
52 kfree(trace_profile_buf_nmi);
54 kfree(trace_profile_buf);
56 total_profile_count--;
57 atomic_dec(&event->profile_count);
62 int ftrace_profile_enable(int event_id)
64 struct ftrace_event_call *event;
67 mutex_lock(&event_mutex);
68 list_for_each_entry(event, &ftrace_events, list) {
69 if (event->id == event_id && event->profile_enable &&
70 try_module_get(event->mod)) {
71 ret = ftrace_profile_enable_event(event);
75 mutex_unlock(&event_mutex);
80 static void ftrace_profile_disable_event(struct ftrace_event_call *event)
84 if (!atomic_add_negative(-1, &event->profile_count))
87 event->profile_disable();
89 if (!--total_profile_count) {
90 buf = trace_profile_buf;
91 rcu_assign_pointer(trace_profile_buf, NULL);
93 nmi_buf = trace_profile_buf_nmi;
94 rcu_assign_pointer(trace_profile_buf_nmi, NULL);
97 * Ensure every events in profiling have finished before
98 * releasing the buffers
103 free_percpu(nmi_buf);
107 void ftrace_profile_disable(int event_id)
109 struct ftrace_event_call *event;
111 mutex_lock(&event_mutex);
112 list_for_each_entry(event, &ftrace_events, list) {
113 if (event->id == event_id) {
114 ftrace_profile_disable_event(event);
115 module_put(event->mod);
119 mutex_unlock(&event_mutex);