2 files changed, 14 insertions, 5 deletions

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 3ffe4c5ad3f3..41473b4ad7a4 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -3998,7 +3998,7 @@ static int ftrace_module_notify(struct notifier_block *self,
 
 struct notifier_block ftrace_module_nb = {
         .notifier_call = ftrace_module_notify,
-        .priority = 0,
+        .priority = INT_MAX,    /* Run before anything that can use kprobes */
 };
 
 extern unsigned long __start_mcount_loc[];
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index e5125677efa0..3c13e46d7d24 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -2899,6 +2899,8 @@ tracing_trace_options_write(struct file *filp, const char __user *ubuf,
         if (copy_from_user(&buf, ubuf, cnt))
                 return -EFAULT;
 
+        buf[cnt] = 0;
+
         trace_set_options(buf);
 
         *ppos += cnt;
@@ -3452,7 +3454,7 @@ static int tracing_wait_pipe(struct file *filp)
                         return -EINTR;
 
                 /*
-                 * We block until we read something and tracing is enabled.
+                 * We block until we read something and tracing is disabled.
                  * We still block if tracing is disabled, but we have never
                  * read anything. This allows a user to cat this file, and
                  * then enable tracing. But after we have read something,
@@ -3460,7 +3462,7 @@ static int tracing_wait_pipe(struct file *filp)
                  *
                  * iter->pos will be 0 if we haven't read anything.
                  */
-                if (tracing_is_enabled() && iter->pos)
+                if (!tracing_is_enabled() && iter->pos)
                         break;
         }
 
@@ -4815,10 +4817,17 @@ rb_simple_write(struct file *filp, const char __user *ubuf,
                 return ret;
 
         if (buffer) {
-                if (val)
+                mutex_lock(&trace_types_lock);
+                if (val) {
                         ring_buffer_record_on(buffer);
-                else
+                        if (current_trace->start)
+                                current_trace->start(tr);
+                } else {
                         ring_buffer_record_off(buffer);
+                        if (current_trace->stop)
+                                current_trace->stop(tr);
+                }
+                mutex_unlock(&trace_types_lock);
         }
 
         (*ppos)++;