perf top: Remove entries from entries_collapsed on decay

We were removing only when using a --sort order that needs collapsing,
while we also use it in the threaded case, causing memory corruption
because we were scribbling freed hist entries, oops.

Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-k16fb4jsulr7x0ixv43amb6d@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/builtin-top.c

@@ -304,7 +304,7 @@ static void print_sym_table(void)
 
 	hists__collapse_resort_threaded(&top.sym_evsel->hists);
 	hists__output_resort_threaded(&top.sym_evsel->hists);
-	hists__decay_entries(&top.sym_evsel->hists);
+	hists__decay_entries_threaded(&top.sym_evsel->hists);
 	hists__output_recalc_col_len(&top.sym_evsel->hists, winsize.ws_row - 3);
 	putchar('\n');
 	hists__fprintf(&top.sym_evsel->hists, NULL, false, false,
@@ -555,7 +555,7 @@ static void perf_top__sort_new_samples(void *arg)
 
 	hists__collapse_resort_threaded(&t->sym_evsel->hists);
 	hists__output_resort_threaded(&t->sym_evsel->hists);
-	hists__decay_entries(&t->sym_evsel->hists);
+	hists__decay_entries_threaded(&t->sym_evsel->hists);
 	hists__output_recalc_col_len(&t->sym_evsel->hists, winsize.ws_row - 3);
 }
 

tools/perf/util/hist.c

@@ -108,7 +108,7 @@ static bool hists__decay_entry(struct hists *hists, struct hist_entry *he)
 	return he->period == 0;
 }
 
-void hists__decay_entries(struct hists *hists)
+static void __hists__decay_entries(struct hists *hists, bool threaded)
 {
 	struct rb_node *next = rb_first(&hists->entries);
 	struct hist_entry *n;
@@ -124,7 +124,7 @@ void hists__decay_entries(struct hists *hists)
 		if (hists__decay_entry(hists, n) && !n->used) {
 			rb_erase(&n->rb_node, &hists->entries);
 
-			if (sort__need_collapse)
+			if (sort__need_collapse || threaded)
 				rb_erase(&n->rb_node_in, &hists->entries_collapsed);
 
 			hist_entry__free(n);
@@ -133,6 +133,16 @@ void hists__decay_entries(struct hists *hists)
 	}
 }
 
+void hists__decay_entries(struct hists *hists)
+{
+	return __hists__decay_entries(hists, false);
+}
+
+void hists__decay_entries_threaded(struct hists *hists)
+{
+	return __hists__decay_entries(hists, true);
+}
+
 /*
  * histogram, sorted on item, collects periods
  */

tools/perf/util/hist.h

@@ -79,6 +79,7 @@ void hists__collapse_resort(struct hists *self);
 void hists__collapse_resort_threaded(struct hists *hists);
 
 void hists__decay_entries(struct hists *hists);
+void hists__decay_entries_threaded(struct hists *hists);
 void hists__output_recalc_col_len(struct hists *hists, int max_rows);
 
 void hists__inc_nr_events(struct hists *self, u32 type);