tracing: Add trace_total_entries() / trace_total_entries_cpu()

These two new exported functions will be used in a future patch by
kdb_ftdump() to quickly skip all but the last few trace entries.

Link: http://lkml.kernel.org/r/20190319171206.97107-2-dianders@chromium.org
Acked-by: Daniel Thompson <daniel.thompson@linaro.org>
Suggested-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 2bc18de7f0dcc5a310c00963eca8b163b46b487b..dcb9adb44be9d2198058c1f03bce683191dbb961 100644 (file)
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -3492,34 +3492,69 @@ static void s_stop(struct seq_file *m, void *p)
        trace_event_read_unlock();
 }
 
+static void
+get_total_entries_cpu(struct trace_buffer *buf, unsigned long *total,
+                     unsigned long *entries, int cpu)
+{
+       unsigned long count;
+
+       count = ring_buffer_entries_cpu(buf->buffer, cpu);
+       /*
+        * If this buffer has skipped entries, then we hold all
+        * entries for the trace and we need to ignore the
+        * ones before the time stamp.
+        */
+       if (per_cpu_ptr(buf->data, cpu)->skipped_entries) {
+               count -= per_cpu_ptr(buf->data, cpu)->skipped_entries;
+               /* total is the same as the entries */
+               *total = count;
+       } else
+               *total = count +
+                       ring_buffer_overrun_cpu(buf->buffer, cpu);
+       *entries = count;
+}
+
 static void
 get_total_entries(struct trace_buffer *buf,
                  unsigned long *total, unsigned long *entries)
 {
-       unsigned long count;
+       unsigned long t, e;
        int cpu;
 
        *total = 0;
        *entries = 0;
 
        for_each_tracing_cpu(cpu) {
-               count = ring_buffer_entries_cpu(buf->buffer, cpu);
-               /*
-                * If this buffer has skipped entries, then we hold all
-                * entries for the trace and we need to ignore the
-                * ones before the time stamp.
-                */
-               if (per_cpu_ptr(buf->data, cpu)->skipped_entries) {
-                       count -= per_cpu_ptr(buf->data, cpu)->skipped_entries;
-                       /* total is the same as the entries */
-                       *total += count;
-               } else
-                       *total += count +
-                               ring_buffer_overrun_cpu(buf->buffer, cpu);
-               *entries += count;
+               get_total_entries_cpu(buf, &t, &e, cpu);
+               *total += t;
+               *entries += e;
        }
 }
 
+unsigned long trace_total_entries_cpu(struct trace_array *tr, int cpu)
+{
+       unsigned long total, entries;
+
+       if (!tr)
+               tr = &global_trace;
+
+       get_total_entries_cpu(&tr->trace_buffer, &total, &entries, cpu);
+
+       return entries;
+}
+
+unsigned long trace_total_entries(struct trace_array *tr)
+{
+       unsigned long total, entries;
+
+       if (!tr)
+               tr = &global_trace;
+
+       get_total_entries(&tr->trace_buffer, &total, &entries);
+
+       return entries;
+}
+
 static void print_lat_help_header(struct seq_file *m)
 {
        seq_puts(m, "#                  _------=> CPU#            \n"

diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index da00a3d508c18a7e6601727cf90d92065e731084..33f14b9e78b7f830e0d5635b775162f11ec31c01 100644 (file)
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -721,6 +721,9 @@ void trace_init_global_iter(struct trace_iterator *iter);
 
 void tracing_iter_reset(struct trace_iterator *iter, int cpu);
 
+unsigned long trace_total_entries_cpu(struct trace_array *tr, int cpu);
+unsigned long trace_total_entries(struct trace_array *tr);
+
 void trace_function(struct trace_array *tr,
                    unsigned long ip,
                    unsigned long parent_ip,