perf callchain: Introduce callchain_cursor__copy()

The callchain_cursor__copy() function is to save current callchain
captured by a cursor.  It'll be used to keep callchains when switching
to idle task for each cpu.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20161206034010.6499-3-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

2 files changed, 30 insertions, 0 deletions

diff --git a/tools/perf/util/callchain.c b/tools/perf/util/callchain.c
index 823befd8209a..42922512c1c6 100644
--- a/tools/perf/util/callchain.c
+++ b/tools/perf/util/callchain.c
@@ -1234,3 +1234,30 @@ out:
         }
         return -ENOMEM;
 }
+
+int callchain_cursor__copy(struct callchain_cursor *dst,
+                           struct callchain_cursor *src)
+{
+        int rc = 0;
+
+        callchain_cursor_reset(dst);
+        callchain_cursor_commit(src);
+
+        while (true) {
+                struct callchain_cursor_node *node;
+
+                node = callchain_cursor_current(src);
+                if (node == NULL)
+                        break;
+
+                rc = callchain_cursor_append(dst, node->ip, node->map, node->sym,
+                                             node->branch, &node->branch_flags,
+                                             node->nr_loop_iter, node->samples);
+                if (rc)
+                        break;
+
+                callchain_cursor_advance(src);
+        }
+
+        return rc;
+}
diff --git a/tools/perf/util/callchain.h b/tools/perf/util/callchain.h
index d9c70dccf06a..35c8e379530f 100644
--- a/tools/perf/util/callchain.h
+++ b/tools/perf/util/callchain.h
@@ -216,6 +216,9 @@ static inline void callchain_cursor_advance(struct callchain_cursor *cursor)
         cursor->pos++;
 }
 
+int callchain_cursor__copy(struct callchain_cursor *dst,
+                           struct callchain_cursor *src);
+
 struct option;
 struct hist_entry;