ftrace: add logic to record overruns

This patch sets up the infrastructure to record overruns of the tracing
buffer.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 5 insertions, 1 deletions

diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 8991c5efcc74..c1ec134ac356 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -97,6 +97,7 @@ struct trace_array_cpu {
         void                    *trace_head; /* producer */
         void                    *trace_tail; /* consumer */
         unsigned long           trace_idx;
+        unsigned long           overrun;
         unsigned long           saved_latency;
         unsigned long           critical_start;
         unsigned long           critical_end;
@@ -157,10 +158,13 @@ struct trace_seq {
  * results to users and which routines might sleep, etc:
  */
 struct trace_iterator {
-        struct trace_seq        seq;
         struct trace_array      *tr;
         struct tracer           *trace;
+        long                    last_overrun[NR_CPUS];
+        long                    overrun[NR_CPUS];
 
+        /* The below is zeroed out in pipe_read */
+        struct trace_seq        seq;
         struct trace_entry      *ent;
         int                     cpu;