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Commit abd82868 authored by Arnaldo Carvalho de Melo's avatar Arnaldo Carvalho de Melo
Browse files

perf thread: Fix reference count initial state 



We should always return from thread__new(), the constructor, with the
object with a reference count of one, so that:

     struct thread *thread = thread__new();
     thread__put(thread);

Will call thread__delete().

If any reference is made to that 'thread' variable, it better use
thread__get(thread) to hold a reference.

We were returning with thread->refcnt set to zero, fix it and some cases
where thread__delete() was being called, which were not a problem
because just one reference was being used, now that we set it to 1, use
thread__put() instead.

Reported-by: default avatarMasami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-4b9mkuk66to4ecckpmpvqx6s@git.kernel.org


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent b6847d2c

tools/perf/util/intel-pt.c

+2 −2
Original line number Diff line number Diff line
@@ -1744,7 +1744,7 @@ static void intel_pt_free(struct perf_session *session) 
	auxtrace_heap__free(&pt->heap);

	intel_pt_free_events(session);

	session->auxtrace = NULL;

	thread__delete(pt->unknown_thread);

	thread__put(pt->unknown_thread);

	free(pt);

}
@@ -2153,7 +2153,7 @@ int intel_pt_process_auxtrace_info(union perf_event *event, 
	return 0;



err_delete_thread:

	thread__delete(pt->unknown_thread);

	thread__zput(pt->unknown_thread);

err_free_queues:

	intel_pt_log_disable();

	auxtrace_queues__free(&pt->queues);

tools/perf/util/machine.c

+12 −7
Original line number Diff line number Diff line
@@ -352,13 +352,18 @@ static void machine__update_thread_pid(struct machine *machine, 
	}



	th->mg = map_groups__get(leader->mg);



out_put:

	thread__put(leader);

	return;



out_err:

	pr_err("Failed to join map groups for %d:%d\n", th->pid_, th->tid);

	goto out_put;

}



/*

 * Caller must eventually drop thread->refcnt returned with a successfull

 * lookup/new thread inserted.

 */

static struct thread *____machine__findnew_thread(struct machine *machine,

						  pid_t pid, pid_t tid,

						  bool create)
@@ -376,7 +381,7 @@ static struct thread *____machine__findnew_thread(struct machine *machine, 
	if (th != NULL) {

		if (th->tid == tid) {

			machine__update_thread_pid(machine, th, pid);

			return th;

			return thread__get(th);

		}



		machine->last_match = NULL;
@@ -389,7 +394,7 @@ static struct thread *____machine__findnew_thread(struct machine *machine, 
		if (th->tid == tid) {

			machine->last_match = th;

			machine__update_thread_pid(machine, th, pid);

			return th;

			return thread__get(th);

		}



		if (tid < th->tid)
@@ -417,7 +422,7 @@ static struct thread *____machine__findnew_thread(struct machine *machine, 
		if (thread__init_map_groups(th, machine)) {

			rb_erase_init(&th->rb_node, &machine->threads);

			RB_CLEAR_NODE(&th->rb_node);

			thread__delete(th);

			thread__put(th);

			return NULL;

		}

		/*
@@ -441,7 +446,7 @@ struct thread *machine__findnew_thread(struct machine *machine, pid_t pid, 
	struct thread *th;



	pthread_rwlock_wrlock(&machine->threads_lock);

	th = thread__get(__machine__findnew_thread(machine, pid, tid));

	th = __machine__findnew_thread(machine, pid, tid);

	pthread_rwlock_unlock(&machine->threads_lock);

	return th;

}
@@ -451,7 +456,7 @@ struct thread *machine__find_thread(struct machine *machine, pid_t pid, 
{

	struct thread *th;

	pthread_rwlock_rdlock(&machine->threads_lock);

	th =  thread__get(____machine__findnew_thread(machine, pid, tid, false));

	th =  ____machine__findnew_thread(machine, pid, tid, false);

	pthread_rwlock_unlock(&machine->threads_lock);

	return th;

}

tools/perf/util/thread.c

+8 −2
Original line number Diff line number Diff line
@@ -19,8 +19,10 @@ int thread__init_map_groups(struct thread *thread, struct machine *machine) 
		thread->mg = map_groups__new(machine);

	} else {

		leader = __machine__findnew_thread(machine, pid, pid);

		if (leader)

		if (leader) {

			thread->mg = map_groups__get(leader->mg);

			thread__put(leader);

		}

	}



	return thread->mg ? 0 : -1;
@@ -53,7 +55,7 @@ struct thread *thread__new(pid_t pid, pid_t tid) 
			goto err_thread;



		list_add(&comm->list, &thread->comm_list);

		atomic_set(&thread->refcnt, 0);

		atomic_set(&thread->refcnt, 1);

		RB_CLEAR_NODE(&thread->rb_node);

	}
@@ -95,6 +97,10 @@ struct thread *thread__get(struct thread *thread) 
void thread__put(struct thread *thread)

{

	if (thread && atomic_dec_and_test(&thread->refcnt)) {

		/*

		 * Remove it from the dead_threads list, as last reference

		 * is gone.

		 */

		list_del_init(&thread->node);

		thread__delete(thread);

	}