ring-buffer: do not swap if recording is disabled

If the ring buffer recording has been disabled. Do not let
swapping of ring buffers occur. Simply return -EAGAIN.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

2 files changed, 16 insertions, 1 deletions

diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 0b9de5a3d699..890020e28a35 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -2266,9 +2266,24 @@ int ring_buffer_swap_cpu(struct ring_buffer *buffer_a,
         if (buffer_a->pages != buffer_b->pages)
                 return -EINVAL;
 
+        if (ring_buffer_flags != RB_BUFFERS_ON)
+                return -EAGAIN;
+
+        if (atomic_read(&buffer_a->record_disabled))
+                return -EAGAIN;
+
+        if (atomic_read(&buffer_b->record_disabled))
+                return -EAGAIN;
+
         cpu_buffer_a = buffer_a->buffers[cpu];
         cpu_buffer_b = buffer_b->buffers[cpu];
 
+        if (atomic_read(&cpu_buffer_a->record_disabled))
+                return -EAGAIN;
+
+        if (atomic_read(&cpu_buffer_b->record_disabled))
+                return -EAGAIN;
+
         /*
          * We can't do a synchronize_sched here because this
          * function can be called in atomic context.
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 220c264e3111..757ae6f7e648 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -415,7 +415,7 @@ update_max_tr_single(struct trace_array *tr, struct task_struct *tsk, int cpu)
 
         ftrace_enable_cpu();
 
-        WARN_ON_ONCE(ret);
+        WARN_ON_ONCE(ret && ret != -EAGAIN);
 
         __update_max_tr(tr, tsk, cpu);
         __raw_spin_unlock(&ftrace_max_lock);