diff --git a/include/linux/relay.h b/include/linux/relay.h
index e13a333e7c37..7333909df65a 100644
--- a/include/linux/relay.h
+++ b/include/linux/relay.h
@@ -62,7 +62,7 @@ struct rchan
 	size_t subbuf_size;		/* sub-buffer size */
 	size_t n_subbufs;		/* number of sub-buffers per buffer */
 	size_t alloc_size;		/* total buffer size allocated */
-	struct rchan_callbacks *cb;	/* client callbacks */
+	const struct rchan_callbacks *cb; /* client callbacks, may be NULL */
 	struct kref kref;		/* channel refcount */
 	void *private_data;		/* for user-defined data */
 	size_t last_toobig;		/* tried to log event > subbuf size */
@@ -170,7 +170,7 @@ struct rchan *relay_open(const char *base_filename,
 			 struct dentry *parent,
 			 size_t subbuf_size,
 			 size_t n_subbufs,
-			 struct rchan_callbacks *cb,
+			 const struct rchan_callbacks *cb,
 			 void *private_data);
 extern int relay_late_setup_files(struct rchan *chan,
 				  const char *base_filename,
diff --git a/kernel/relay.c b/kernel/relay.c
index b08d936d5fa7..c53676f2d10f 100644
--- a/kernel/relay.c
+++ b/kernel/relay.c
@@ -27,13 +27,86 @@
 static DEFINE_MUTEX(relay_channels_mutex);
 static LIST_HEAD(relay_channels);
 
+/*
+ * rchan_callback wrappers. Call the callbacks if available, otherwise fall back
+ * to default behaviour.
+ */
+
+/*
+ * subbuf_start() callback.
+ */
+static int cb_subbuf_start(const struct rchan_callbacks *cb,
+			   struct rchan_buf *buf,
+			   void *subbuf,
+			   void *prev_subbuf,
+			   size_t prev_padding)
+{
+	if (cb && cb->subbuf_start)
+		return cb->subbuf_start(buf, subbuf, prev_subbuf, prev_padding);
+
+	if (relay_buf_full(buf))
+		return 0;
+
+	return 1;
+}
+
+/*
+ * buf_mapped() callback.
+ */
+static void cb_buf_mapped(const struct rchan_callbacks *cb,
+			  struct rchan_buf *buf,
+			  struct file *filp)
+{
+	if (cb && cb->buf_mapped)
+		cb->buf_mapped(buf, filp);
+}
+
+/*
+ * buf_unmapped() callback.
+ */
+static void cb_buf_unmapped(const struct rchan_callbacks *cb,
+			    struct rchan_buf *buf,
+			    struct file *filp)
+{
+	if (cb && cb->buf_unmapped)
+		cb->buf_unmapped(buf, filp);
+}
+
+/*
+ * create_buf_file_create() callback.
+ */
+static struct dentry *cb_create_buf_file(const struct rchan_callbacks *cb,
+					 const char *filename,
+					 struct dentry *parent,
+					 umode_t mode,
+					 struct rchan_buf *buf,
+					 int *is_global)
+{
+	if (cb && cb->create_buf_file)
+		return cb->create_buf_file(filename, parent, mode, buf, is_global);
+
+	return NULL;
+}
+
+/*
+ * remove_buf_file() callback.
+ */
+static int cb_remove_buf_file(const struct rchan_callbacks *cb,
+			      struct dentry *dentry)
+{
+	if (cb && cb->remove_buf_file)
+		return cb->remove_buf_file(dentry);
+
+	return -EINVAL;
+}
+
 /*
  * close() vm_op implementation for relay file mapping.
  */
 static void relay_file_mmap_close(struct vm_area_struct *vma)
 {
 	struct rchan_buf *buf = vma->vm_private_data;
-	buf->chan->cb->buf_unmapped(buf, vma->vm_file);
+	cb_buf_unmapped(buf->chan->cb, buf, vma->vm_file);
 }
 
 /*
@@ -107,7 +180,7 @@ static int relay_mmap_buf(struct rchan_buf *buf, struct vm_area_struct *vma)
 	vma->vm_ops = &relay_file_mmap_ops;
 	vma->vm_flags |= VM_DONTEXPAND;
 	vma->vm_private_data = buf;
-	buf->chan->cb->buf_mapped(buf, filp);
+	cb_buf_mapped(buf->chan->cb, buf, filp);
 
 	return 0;
 }
@@ -264,70 +337,6 @@ EXPORT_SYMBOL_GPL(relay_buf_full);
  * High-level relay kernel API and associated functions.
  */
 
-/*
- * rchan_callback implementations defining default channel behavior.  Used
- * in place of corresponding NULL values in client callback struct.
- */
-
-/*
- * subbuf_start() default callback.  Does nothing.
- */
-static int subbuf_start_default_callback (struct rchan_buf *buf,
-					  void *subbuf,
-					  void *prev_subbuf,
-					  size_t prev_padding)
-{
-	if (relay_buf_full(buf))
-		return 0;
-
-	return 1;
-}
-
-/*
- * buf_mapped() default callback.  Does nothing.
- */
-static void buf_mapped_default_callback(struct rchan_buf *buf,
-					struct file *filp)
-{
-}
-
-/*
- * buf_unmapped() default callback.  Does nothing.
- */
-static void buf_unmapped_default_callback(struct rchan_buf *buf,
-					  struct file *filp)
-{
-}
-
-/*
- * create_buf_file_create() default callback.  Does nothing.
- */
-static struct dentry *create_buf_file_default_callback(const char *filename,
-						       struct dentry *parent,
-						       umode_t mode,
-						       struct rchan_buf *buf,
-						       int *is_global)
-{
-	return NULL;
-}
-
-/*
- * remove_buf_file() default callback.  Does nothing.
- */
-static int remove_buf_file_default_callback(struct dentry *dentry)
-{
-	return -EINVAL;
-}
-
-/* relay channel default callbacks */
-static struct rchan_callbacks default_channel_callbacks = {
-	.subbuf_start = subbuf_start_default_callback,
-	.buf_mapped = buf_mapped_default_callback,
-	.buf_unmapped = buf_unmapped_default_callback,
-	.create_buf_file = create_buf_file_default_callback,
-	.remove_buf_file = remove_buf_file_default_callback,
-};
-
 /**
  *	wakeup_readers - wake up readers waiting on a channel
  *	@work: contains the channel buffer
@@ -371,7 +380,7 @@ static void __relay_reset(struct rchan_buf *buf, unsigned int init)
 	for (i = 0; i < buf->chan->n_subbufs; i++)
 		buf->padding[i] = 0;
 
-	buf->chan->cb->subbuf_start(buf, buf->data, NULL, 0);
+	cb_subbuf_start(buf->chan->cb, buf, buf->data, NULL, 0);
 }
 
 /**
@@ -426,9 +435,8 @@ static struct dentry *relay_create_buf_file(struct rchan *chan,
 	snprintf(tmpname, NAME_MAX, "%s%d", chan->base_filename, cpu);
 
 	/* Create file in fs */
-	dentry = chan->cb->create_buf_file(tmpname, chan->parent,
-					   S_IRUSR, buf,
-					   &chan->is_global);
+	dentry = cb_create_buf_file(chan->cb, tmpname, chan->parent,
+				    S_IRUSR, buf, &chan->is_global);
 	if (IS_ERR(dentry))
 		dentry = NULL;
 
@@ -461,9 +469,8 @@ static struct rchan_buf *relay_open_buf(struct rchan *chan, unsigned int cpu)
 		relay_set_buf_dentry(buf, dentry);
 	} else {
 		/* Only retrieve global info, nothing more, nothing less */
-		dentry = chan->cb->create_buf_file(NULL, NULL,
-						   S_IRUSR, buf,
-						   &chan->is_global);
+		dentry = cb_create_buf_file(chan->cb, NULL, NULL,
+					    S_IRUSR, buf, &chan->is_global);
 		if (IS_ERR_OR_NULL(dentry))
 			goto free_buf;
 	}
@@ -495,31 +502,10 @@ static void relay_close_buf(struct rchan_buf *buf)
 {
 	buf->finalized = 1;
 	irq_work_sync(&buf->wakeup_work);
-	buf->chan->cb->remove_buf_file(buf->dentry);
+	cb_remove_buf_file(buf->chan->cb, buf->dentry);
 	kref_put(&buf->kref, relay_remove_buf);
 }
 
-static void setup_callbacks(struct rchan *chan,
-				   struct rchan_callbacks *cb)
-{
-	if (!cb) {
-		chan->cb = &default_channel_callbacks;
-		return;
-	}
-
-	if (!cb->subbuf_start)
-		cb->subbuf_start = subbuf_start_default_callback;
-	if (!cb->buf_mapped)
-		cb->buf_mapped = buf_mapped_default_callback;
-	if (!cb->buf_unmapped)
-		cb->buf_unmapped = buf_unmapped_default_callback;
-	if (!cb->create_buf_file)
-		cb->create_buf_file = create_buf_file_default_callback;
-	if (!cb->remove_buf_file)
-		cb->remove_buf_file = remove_buf_file_default_callback;
-	chan->cb = cb;
-}
-
 int relay_prepare_cpu(unsigned int cpu)
 {
 	struct rchan *chan;
@@ -565,7 +551,7 @@ struct rchan *relay_open(const char *base_filename,
 			 struct dentry *parent,
 			 size_t subbuf_size,
 			 size_t n_subbufs,
-			 struct rchan_callbacks *cb,
+			 const struct rchan_callbacks *cb,
 			 void *private_data)
 {
 	unsigned int i;
@@ -597,7 +583,7 @@ struct rchan *relay_open(const char *base_filename,
 		chan->has_base_filename = 1;
 		strlcpy(chan->base_filename, base_filename, NAME_MAX);
 	}
-	setup_callbacks(chan, cb);
+	chan->cb = cb;
 	kref_init(&chan->kref);
 
 	mutex_lock(&relay_channels_mutex);
@@ -780,7 +766,7 @@ size_t relay_switch_subbuf(struct rchan_buf *buf, size_t length)
 	new_subbuf = buf->subbufs_produced % buf->chan->n_subbufs;
 	new = buf->start + new_subbuf * buf->chan->subbuf_size;
 	buf->offset = 0;
-	if (!buf->chan->cb->subbuf_start(buf, new, old, buf->prev_padding)) {
+	if (!cb_subbuf_start(buf->chan->cb, buf, new, old, buf->prev_padding)) {
 		buf->offset = buf->chan->subbuf_size + 1;
 		return 0;
 	}
