X-Git-Url: http://git.lttng.org./?a=blobdiff_plain;f=lib%2Fringbuffer%2Fring_buffer_frontend.c;h=3003dd8324458ee62c8e99460b295bc3ab8e481d;hb=cac8f1aa8774b81f6fe72f670a9413d9287db263;hp=ecc72ab84f7e3143f930e77cac0bc6ad3de16a8e;hpb=d01202ff1f043dd04f62ab77aacea3c26cb65eb3;p=lttng-modules.git

diff --git a/lib/ringbuffer/ring_buffer_frontend.c b/lib/ringbuffer/ring_buffer_frontend.c
index ecc72ab8..3003dd83 100644
--- a/lib/ringbuffer/ring_buffer_frontend.c
+++ b/lib/ringbuffer/ring_buffer_frontend.c
@@ -164,7 +164,6 @@ int lib_ring_buffer_create(struct lib_ring_buffer *buf,
 	const struct lib_ring_buffer_config *config = chanb->config;
 	struct channel *chan = container_of(chanb, struct channel, backend);
 	void *priv = chanb->priv;
-	unsigned int num_subbuf;
 	size_t subbuf_header_size;
 	u64 tsc;
 	int ret;
@@ -203,8 +202,8 @@ int lib_ring_buffer_create(struct lib_ring_buffer *buf,
 		goto free_commit;
 	}
 
-	num_subbuf = chan->backend.num_subbuf;
 	init_waitqueue_head(&buf->read_wait);
+	init_waitqueue_head(&buf->write_wait);
 	raw_spin_lock_init(&buf->raw_tick_nohz_spinlock);
 
 	/*
@@ -700,11 +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)
 {
@@ -753,8 +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);
@@ -869,6 +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
  */
@@ -890,6 +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);