[PATCH 6/8] perf thread-stack: Allocate an array of thread stacks

[Adrian Hunter]

In preparation for fixing thread stack processing for the idle task,
allocate an array of thread stacks.

Signed-off-by: Adrian Hunter <adrian.hun...@intel.com>
---
 tools/perf/util/thread-stack.c | 30 ++++++++++++++++++------------
 1 file changed, 18 insertions(+), 12 deletions(-)

diff --git a/tools/perf/util/thread-stack.c b/tools/perf/util/thread-stack.c
index 4340381d54c2..a896d89fe5f7 100644
--- a/tools/perf/util/thread-stack.c
+++ b/tools/perf/util/thread-stack.c
@@ -114,20 +114,26 @@ static int thread_stack__init(struct thread_stack *ts, 
struct thread *thread,
 static struct thread_stack *thread_stack__new(struct thread *thread,
                                              struct call_return_processor *crp)
 {
-       struct thread_stack *ts;
-
-       ts = zalloc(sizeof(struct thread_stack));
-       if (!ts)
-               return NULL;
-
-       ts->arr_sz = 1;
-
-       if (thread_stack__init(ts, thread, crp)) {
-               free(ts);
-               return NULL;
+       struct thread_stack *ts = thread->ts, *new_ts;
+       unsigned int old_sz = ts ? ts->arr_sz : 0;
+       unsigned int new_sz = 1;
+
+       if (!ts || new_sz > old_sz) {
+               new_ts = calloc(new_sz, sizeof(*ts));
+               if (!new_ts)
+                       return NULL;
+               if (ts)
+                       memcpy(new_ts, ts, old_sz * sizeof(*ts));
+               new_ts->arr_sz = new_sz;
+               if (thread->ts)
+                       zfree(&thread->ts);
+               thread->ts = new_ts;
+               ts = new_ts;
        }
 
-       thread->ts = ts;
+       if (!ts->stack &&
+           thread_stack__init(ts, thread, crp))
+               return NULL;
 
        return ts;
 }
-- 
2.17.1