Add exit to ring_buffer_frontend so module is unloadable

[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 77356fab5b260b16201a42229ec7c7496a058395..4ab474aadfe06dbefd1bc146b41a356e59d6347c 100644 (file)
--- a/lib/ringbuffer/ring_buffer_frontend.c
+++ b/lib/ringbuffer/ring_buffer_frontend.c
@@ -203,6 +203,7 @@ int lib_ring_buffer_create(struct lib_ring_buffer *buf,
        }
 
        init_waitqueue_head(&buf->read_wait);
+       init_waitqueue_head(&buf->write_wait);
        raw_spin_lock_init(&buf->raw_tick_nohz_spinlock);
 
        /*
@@ -698,11 +699,11 @@ void channel_release(struct kref *kref)
  * @chan: channel to destroy
  *
  * Holds cpu hotplug.
- * Call "destroy" callback, finalize channels, wait for readers to release their
- * reference, then destroy ring buffer data. Note that when readers have
- * completed data consumption of finalized channels, get_subbuf() will return
- * -ENODATA. They should release their handle at that point.
- * Returns the private data pointer.
+ * Call "destroy" callback, finalize channels, and then decrement the
+ * channel reference count.  Note that when readers have completed data
+ * consumption of finalized channels, get_subbuf() will return -ENODATA.
+ * They should release their handle at that point.  Returns the private
+ * data pointer.
  */
 void *channel_destroy(struct channel *chan)
 {
@@ -751,8 +752,8 @@ void *channel_destroy(struct channel *chan)
        ACCESS_ONCE(chan->finalized) = 1;
        wake_up_interruptible(&chan->hp_wait);
        wake_up_interruptible(&chan->read_wait);
-       kref_put(&chan->ref, channel_release);
        priv = chan->backend.priv;
+       kref_put(&chan->ref, channel_release);
        return priv;
 }
 EXPORT_SYMBOL_GPL(channel_destroy);
@@ -867,6 +868,8 @@ EXPORT_SYMBOL_GPL(lib_ring_buffer_snapshot);
 
 /**
  * lib_ring_buffer_put_snapshot - move consumed counter forward
+ *
+ * Should only be called from consumer context.
  * @buf: ring buffer
  * @consumed_new: new consumed count value
  */
@@ -888,6 +891,8 @@ void lib_ring_buffer_move_consumer(struct lib_ring_buffer *buf,
        while ((long) consumed - (long) consumed_new < 0)
                consumed = atomic_long_cmpxchg(&buf->consumed, consumed,
                                               consumed_new);
+       /* Wake-up the metadata producer */
+       wake_up_interruptible(&buf->write_wait);
 }
 EXPORT_SYMBOL_GPL(lib_ring_buffer_move_consumer);
 
@@ -1697,3 +1702,20 @@ int lib_ring_buffer_reserve_slow(struct lib_ring_buffer_ctx *ctx)
        return 0;
 }
 EXPORT_SYMBOL_GPL(lib_ring_buffer_reserve_slow);
+
+int __init init_lib_ring_buffer_frontend(void)
+{
+       int cpu;
+
+       for_each_possible_cpu(cpu)
+               spin_lock_init(&per_cpu(ring_buffer_nohz_lock, cpu));
+       return 0;
+}
+
+module_init(init_lib_ring_buffer_frontend);
+
+void __exit exit_lib_ring_buffer_frontend(void)
+{
+}
+
+module_exit(exit_lib_ring_buffer_frontend);