tracing: add protection around modify trace event fields

The trace event objects are currently not proctected against
reentrancy. This patch adds a mutex around the modifications of
the trace event fields.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>

1 files changed, 7 insertions, 0 deletions

diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 1d07f800a9ce..26069fa6b3b0 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -14,6 +14,8 @@
 
 #define TRACE_SYSTEM "TRACE_SYSTEM"
 
+static DEFINE_MUTEX(event_mutex);
+
 #define events_for_each(event)                                          \
         for (event = __start_ftrace_events;                             \
              (unsigned long)event < (unsigned long)__stop_ftrace_events; \
@@ -104,6 +106,7 @@ static int ftrace_set_clr_event(char *buf, int set)
                         event = NULL;
         }
 
+        mutex_lock(&event_mutex);
         events_for_each(call) {
 
                 if (!call->name)
@@ -124,6 +127,8 @@ static int ftrace_set_clr_event(char *buf, int set)
 
                 ret = 0;
         }
+        mutex_unlock(&event_mutex);
+
         return ret;
 }
 
@@ -324,7 +329,9 @@ event_enable_write(struct file *filp, const char __user *ubuf, size_t cnt,
         switch (val) {
         case 0:
         case 1:
+                mutex_lock(&event_mutex);
                 ftrace_event_enable_disable(call, val);
+                mutex_unlock(&event_mutex);
                 break;
 
         default: