Fix teardown deadlock

[lttng-modules.git] / lib / ringbuffer / ring_buffer_frontend.c

diff --git a/lib/ringbuffer/ring_buffer_frontend.c b/lib/ringbuffer/ring_buffer_frontend.c
index 5e633f438f32e57ad2793c4f4e89e56e5a0ce052..7d4dd8380638adf09262fbe30ddd55b34a486c65 100644 (file)
--- a/lib/ringbuffer/ring_buffer_frontend.c
+++ b/lib/ringbuffer/ring_buffer_frontend.c
@@ -624,6 +624,7 @@ struct channel *channel_create(const struct lib_ring_buffer_config *config,
        chan->commit_count_mask = (~0UL >> chan->backend.num_subbuf_order);
        chan->switch_timer_interval = usecs_to_jiffies(switch_timer_interval);
        chan->read_timer_interval = usecs_to_jiffies(read_timer_interval);
+       kref_init(&chan->ref);
        init_waitqueue_head(&chan->read_wait);
 
        if (config->alloc == RING_BUFFER_ALLOC_PER_CPU) {
@@ -685,6 +686,13 @@ error:
 }
 EXPORT_SYMBOL_GPL(channel_create);
 
+static
+void channel_release(struct kref *kref)
+{
+       struct channel *chan = container_of(kref, struct channel, ref);
+       channel_free(chan);
+}
+
 /**
  * channel_destroy - Finalize, wait for q.s. and destroy channel.
  * @chan: channel to destroy
@@ -741,13 +749,8 @@ void *channel_destroy(struct channel *chan)
                wake_up_interruptible(&buf->read_wait);
        }
        wake_up_interruptible(&chan->read_wait);
-
-       while (atomic_long_read(&chan->read_ref) > 0)
-               msleep(100);
-       /* Finish waiting for refcount before free */
-       smp_mb();
+       kref_put(&chan->ref, channel_release);
        priv = chan->backend.priv;
-       channel_free(chan);
        return priv;
 }
 EXPORT_SYMBOL_GPL(channel_destroy);
@@ -769,7 +772,7 @@ int lib_ring_buffer_open_read(struct lib_ring_buffer *buf)
 
        if (!atomic_long_add_unless(&buf->active_readers, 1, 1))
                return -EBUSY;
-       atomic_long_inc(&chan->read_ref);
+       kref_get(&chan->ref);
        smp_mb__after_atomic_inc();
        return 0;
 }
@@ -781,8 +784,8 @@ void lib_ring_buffer_release_read(struct lib_ring_buffer *buf)
 
        CHAN_WARN_ON(chan, atomic_long_read(&buf->active_readers) != 1);
        smp_mb__before_atomic_dec();
-       atomic_long_dec(&chan->read_ref);
        atomic_long_dec(&buf->active_readers);
+       kref_put(&chan->ref, channel_release);
 }
 EXPORT_SYMBOL_GPL(lib_ring_buffer_release_read);