Merge tag 'trace-v3.20' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt...

[linux-drm-fsl-dcu.git] / kernel / trace / trace_events.c

diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 4ff8c1394017a2a3dd74114f921206f9281a32bd..db54dda10ccc179f733db8fd8407cc402c11e409 100644 (file)
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -2429,12 +2429,39 @@ static __init int event_trace_memsetup(void)
        return 0;
 }
 
+static __init void
+early_enable_events(struct trace_array *tr, bool disable_first)
+{
+       char *buf = bootup_event_buf;
+       char *token;
+       int ret;
+
+       while (true) {
+               token = strsep(&buf, ",");
+
+               if (!token)
+                       break;
+               if (!*token)
+                       continue;
+
+               /* Restarting syscalls requires that we stop them first */
+               if (disable_first)
+                       ftrace_set_clr_event(tr, token, 0);
+
+               ret = ftrace_set_clr_event(tr, token, 1);
+               if (ret)
+                       pr_warn("Failed to enable trace event: %s\n", token);
+
+               /* Put back the comma to allow this to be called again */
+               if (buf)
+                       *(buf - 1) = ',';
+       }
+}
+
 static __init int event_trace_enable(void)
 {
        struct trace_array *tr = top_trace_array();
        struct ftrace_event_call **iter, *call;
-       char *buf = bootup_event_buf;
-       char *token;
        int ret;
 
        if (!tr)
@@ -2456,18 +2483,7 @@ static __init int event_trace_enable(void)
         */
        __trace_early_add_events(tr);
 
-       while (true) {
-               token = strsep(&buf, ",");
-
-               if (!token)
-                       break;
-               if (!*token)
-                       continue;
-
-               ret = ftrace_set_clr_event(tr, token, 1);
-               if (ret)
-                       pr_warn("Failed to enable trace event: %s\n", token);
-       }
+       early_enable_events(tr, false);
 
        trace_printk_start_comm();
 
@@ -2478,6 +2494,31 @@ static __init int event_trace_enable(void)
        return 0;
 }
 
+/*
+ * event_trace_enable() is called from trace_event_init() first to
+ * initialize events and perhaps start any events that are on the
+ * command line. Unfortunately, there are some events that will not
+ * start this early, like the system call tracepoints that need
+ * to set the TIF_SYSCALL_TRACEPOINT flag of pid 1. But event_trace_enable()
+ * is called before pid 1 starts, and this flag is never set, making
+ * the syscall tracepoint never get reached, but the event is enabled
+ * regardless (and not doing anything).
+ */
+static __init int event_trace_enable_again(void)
+{
+       struct trace_array *tr;
+
+       tr = top_trace_array();
+       if (!tr)
+               return -ENODEV;
+
+       early_enable_events(tr, true);
+
+       return 0;
+}
+
+early_initcall(event_trace_enable_again);
+
 static __init int event_trace_init(void)
 {
        struct trace_array *tr;