tracing: print out start and stop in latency traces

During development of the tracer, we would copy information from
the live tracer to the max tracer with one memcpy. Since then we
added a generic ring buffer and we handle the copies differently now.
Unfortunately, we never copied the critical section information, and
we lost the output:

 #  => started at: kmem_cache_alloc
 #  => ended at:   kmem_cache_alloc

This patch adds back the critical start and end copying as well as
removes the unused "trace_idx" and "overrun" fields of the
trace_array_cpu structure.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 11 insertions, 8 deletions

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 0f0881676dc9..df2c9f730ac6 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -407,19 +407,22 @@ static void
 __update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu)
 {
         struct trace_array_cpu *data = tr->data[cpu];
+        struct trace_array_cpu *max_data = tr->data[cpu];
 
         max_tr.cpu = cpu;
         max_tr.time_start = data->preempt_timestamp;
 
-        data = max_tr.data[cpu];
-        data->saved_latency = tracing_max_latency;
+        max_data = max_tr.data[cpu];
+        max_data->saved_latency = tracing_max_latency;
+        max_data->critical_start = data->critical_start;
+        max_data->critical_end = data->critical_end;
 
         memcpy(data->comm, tsk->comm, TASK_COMM_LEN);
-        data->pid = tsk->pid;
-        data->uid = task_uid(tsk);
-        data->nice = tsk->static_prio - 20 - MAX_RT_PRIO;
-        data->policy = tsk->policy;
-        data->rt_priority = tsk->rt_priority;
+        max_data->pid = tsk->pid;
+        max_data->uid = task_uid(tsk);
+        max_data->nice = tsk->static_prio - 20 - MAX_RT_PRIO;
+        max_data->policy = tsk->policy;
+        max_data->rt_priority = tsk->rt_priority;
 
         /* record this tasks comm */
         tracing_record_cmdline(tsk);
@@ -1501,7 +1504,7 @@ print_trace_header(struct seq_file *m, struct trace_iterator *iter)
                 seq_puts(m, "\n#  => ended at:   ");
                 seq_print_ip_sym(&iter->seq, data->critical_end, sym_flags);
                 trace_print_seq(m, &iter->seq);
-                seq_puts(m, "#\n");
+                seq_puts(m, "\n#\n");
         }
 
         seq_puts(m, "#\n");