Merge branch 'tracing/core-v3' of git://git.kernel.org/pub/scm/linux/kernel/git/frederic/random-tracing into tracing/urgent

1 files changed, 77 insertions, 2 deletions

diff --git a/kernel/trace/trace_event_profile.c b/kernel/trace/trace_event_profile.c
index 55a25c933d15..3aaa77c3309b 100644
--- a/kernel/trace/trace_event_profile.c
+++ b/kernel/trace/trace_event_profile.c
@@ -8,6 +8,54 @@
 #include <linux/module.h>
 #include "trace.h"
 
+/*
+ * We can't use a size but a type in alloc_percpu()
+ * So let's create a dummy type that matches the desired size
+ */
+typedef struct {char buf[FTRACE_MAX_PROFILE_SIZE];} profile_buf_t;
+
+char            *trace_profile_buf;
+char            *trace_profile_buf_nmi;
+
+/* 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 (atomic_inc_return(&event->profile_count))
+                return 0;
+
+        if (!total_profile_count++) {
+                buf = (char *)alloc_percpu(profile_buf_t);
+                if (!buf)
+                        goto fail_buf;
+
+                rcu_assign_pointer(trace_profile_buf, buf);
+
+                buf = (char *)alloc_percpu(profile_buf_t);
+                if (!buf)
+                        goto fail_buf_nmi;
+
+                rcu_assign_pointer(trace_profile_buf_nmi, buf);
+        }
+
+        ret = event->profile_enable();
+        if (!ret)
+                return 0;
+
+        kfree(trace_profile_buf_nmi);
+fail_buf_nmi:
+        kfree(trace_profile_buf);
+fail_buf:
+        total_profile_count--;
+        atomic_dec(&event->profile_count);
+
+        return ret;
+}
+
 int ftrace_profile_enable(int event_id)
 {
         struct ftrace_event_call *event;
@@ -17,7 +65,7 @@ int ftrace_profile_enable(int event_id)
         list_for_each_entry(event, &ftrace_events, list) {
                 if (event->id == event_id && event->profile_enable &&
                     try_module_get(event->mod)) {
-                        ret = event->profile_enable(event);
+                        ret = ftrace_profile_enable_event(event);
                         break;
                 }
         }
@@ -26,6 +74,33 @@ int ftrace_profile_enable(int event_id)
         return ret;
 }
 
+static void ftrace_profile_disable_event(struct ftrace_event_call *event)
+{
+        char *buf, *nmi_buf;
+
+        if (!atomic_add_negative(-1, &event->profile_count))
+                return;
+
+        event->profile_disable();
+
+        if (!--total_profile_count) {
+                buf = trace_profile_buf;
+                rcu_assign_pointer(trace_profile_buf, NULL);
+
+                nmi_buf = trace_profile_buf_nmi;
+                rcu_assign_pointer(trace_profile_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;
@@ -33,7 +108,7 @@ void ftrace_profile_disable(int event_id)
         mutex_lock(&event_mutex);
         list_for_each_entry(event, &ftrace_events, list) {
                 if (event->id == event_id) {
-                        event->profile_disable(event);
+                        ftrace_profile_disable_event(event);
                         module_put(event->mod);
                         break;
                 }