5 files changed, 47 insertions, 14 deletions
diff --git a/tools/perf/tests/shell/record+probe_libc_inet_pton.sh b/tools/perf/tests/shell/record+probe_libc_inet_pton.sh
index 9b7632ff70aa..f12a4e217968 100755
--- a/tools/perf/tests/shell/record+probe_libc_inet_pton.sh
+++ b/tools/perf/tests/shell/record+probe_libc_inet_pton.sh
@@ -45,7 +45,7 @@ trace_libc_inet_pton_backtrace() {
 		eventattr='max-stack=4'
 		echo "gaih_inet.*\+0x[[:xdigit:]]+[[:space:]]\($libc\)$" >> $expected
 		echo "getaddrinfo\+0x[[:xdigit:]]+[[:space:]]\($libc\)$" >> $expected
-		echo ".*\+0x[[:xdigit:]]+[[:space:]]\(.*/bin/ping.*\)$" >> $expected
+		echo ".*(\+0x[[:xdigit:]]+|\[unknown\])[[:space:]]\(.*/bin/ping.*\)$" >> $expected
 		;;
 	*)
 		eventattr='max-stack=3'
diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index 5ab31a4a658d..7fb4ae82f34c 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -1800,14 +1800,8 @@ static int perf_event_open(struct perf_evsel *evsel,
 		if (fd >= 0)
 			break;
 
-		/*
-		 * Do quick precise_ip fallback if:
-		 *  - there is precise_ip set in perf_event_attr
-		 *  - maximum precise is requested
-		 *  - sys_perf_event_open failed with ENOTSUP error,
-		 *    which is associated with wrong precise_ip
-		 */
-		if (!precise_ip || !evsel->precise_max || (errno != ENOTSUP))
+		/* Do not try less precise if not requested. */
+		if (!evsel->precise_max)
 			break;
 
 		/*
diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
index bf26dc85eaaa..6a93ff5d8db5 100644
--- a/tools/perf/util/header.c
+++ b/tools/perf/util/header.c
@@ -3683,6 +3683,7 @@ int perf_event__synthesize_features(struct perf_tool *tool,
 		return -ENOMEM;
 
 	ff.size = sz - sz_hdr;
+	ff.ph = &session->header;
 
 	for_each_set_bit(feat, header->adds_features, HEADER_FEAT_BITS) {
 		if (!feat_ops[feat].synthesize) {
diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index 1b3d7265bca9..147ed85ea2bc 100644
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -210,6 +210,18 @@ void machine__exit(struct machine *machine)
 
 	for (i = 0; i < THREADS__TABLE_SIZE; i++) {
 		struct threads *threads = &machine->threads[i];
+		struct thread *thread, *n;
+		/*
+		 * Forget about the dead, at this point whatever threads were
+		 * left in the dead lists better have a reference count taken
+		 * by who is using them, and then, when they drop those references
+		 * and it finally hits zero, thread__put() will check and see that
+		 * its not in the dead threads list and will not try to remove it
+		 * from there, just calling thread__delete() straight away.
+		 */
+		list_for_each_entry_safe(thread, n, &threads->dead, node)
+			list_del_init(&thread->node);
+
 		exit_rwsem(&threads->lock);
 	}
 }
@@ -1759,9 +1771,11 @@ static void __machine__remove_thread(struct machine *machine, struct thread *th,
 	if (threads->last_match == th)
 		threads__set_last_match(threads, NULL);
 
-	BUG_ON(refcount_read(&th->refcnt) == 0);
 	if (lock)
 		down_write(&threads->lock);
+
+	BUG_ON(refcount_read(&th->refcnt) == 0);
+
 	rb_erase_cached(&th->rb_node, &threads->entries);
 	RB_CLEAR_NODE(&th->rb_node);
 	--threads->nr;
@@ -1771,9 +1785,16 @@ static void __machine__remove_thread(struct machine *machine, struct thread *th,
 	 * will be called and we will remove it from the dead_threads list.
 	 */
 	list_add_tail(&th->node, &threads->dead);
+
+	/*
+	 * We need to do the put here because if this is the last refcount,
+	 * then we will be touching the threads->dead head when removing the
+	 * thread.
+	 */
+	thread__put(th);
+
 	if (lock)
 		up_write(&threads->lock);
-	thread__put(th);
 }
 
 void machine__remove_thread(struct machine *machine, struct thread *th)
diff --git a/tools/perf/util/thread.c b/tools/perf/util/thread.c
index aab7807d445f..3e29a4e8b5e6 100644
--- a/tools/perf/util/thread.c
+++ b/tools/perf/util/thread.c
@@ -125,10 +125,27 @@ void thread__put(struct thread *thread)
 {
 	if (thread && refcount_dec_and_test(&thread->refcnt)) {
 		/*
-		 * Remove it from the dead_threads list, as last reference
-		 * is gone.
+		 * Remove it from the dead threads list, as last reference is
+		 * gone, if it is in a dead threads list.
+		 *
+		 * We may not be there anymore if say, the machine where it was
+		 * stored was already deleted, so we already removed it from
+		 * the dead threads and some other piece of code still keeps a
+		 * reference.
+		 *
+		 * This is what 'perf sched' does and finally drops it in
+		 * perf_sched__lat(), where it calls perf_sched__read_events(),
+		 * that processes the events by creating a session and deleting
+		 * it, which ends up destroying the list heads for the dead
+		 * threads, but before it does that it removes all threads from
+		 * it using list_del_init().
+		 *
+		 * So we need to check here if it is in a dead threads list and
+		 * if so, remove it before finally deleting the thread, to avoid
+		 * an use after free situation.
 		 */
-		list_del_init(&thread->node);
+		if (!list_empty(&thread->node))
+			list_del_init(&thread->node);
 		thread__delete(thread);
 	}
 }