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-rw-r--r--kernel/trace/trace_events.c71
1 files changed, 56 insertions, 15 deletions
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 366a78a3e61e..db54dda10ccc 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;
@@ -2490,7 +2531,7 @@ static __init int event_trace_init(void)
return -ENODEV;
d_tracer = tracing_init_dentry();
- if (!d_tracer)
+ if (IS_ERR(d_tracer))
return 0;
entry = debugfs_create_file("available_events", 0444, d_tracer,