1 files changed, 55 insertions, 14 deletions

diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 366a78a3e61e..b03a0ea77b99 100644
--- 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;