perf tools: Introduce pstack_peek()

The pstack_peek() is to get the topmost entry without removing it.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1429838133-14001-1-git-send-email-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/util/pstack.c b/tools/perf/util/pstack.c
index a126e6cc6e73ad8554e21a611b373a25599f5a9a..b234a6e3d0d4f378ff2fd4899159bd3190956a99 100644 (file)
--- a/tools/perf/util/pstack.c
+++ b/tools/perf/util/pstack.c
@@ -74,3 +74,10 @@ void *pstack__pop(struct pstack *pstack)
        pstack->entries[pstack->top] = NULL;
        return ret;
 }
+
+void *pstack__peek(struct pstack *pstack)
+{
+       if (pstack->top == 0)
+               return NULL;
+       return pstack->entries[pstack->top - 1];
+}

diff --git a/tools/perf/util/pstack.h b/tools/perf/util/pstack.h
index c3cb6584d52763f24c3074886de50c9ff741c71c..ded7f2e36624a9ff2d6ebe49c92aed2018c097dc 100644 (file)
--- a/tools/perf/util/pstack.h
+++ b/tools/perf/util/pstack.h
@@ -10,5 +10,6 @@ bool pstack__empty(const struct pstack *pstack);
 void pstack__remove(struct pstack *pstack, void *key);
 void pstack__push(struct pstack *pstack, void *key);
 void *pstack__pop(struct pstack *pstack);
+void *pstack__peek(struct pstack *pstack);
 
 #endif /* _PERF_PSTACK_ */