[PATCH v14 08/30] tracing: Add init callback to trace remotes

[Vincent Donnefort <vdonnefort@google.com>]

Add a .init call back so the trace remote callers can add entries to the
tracefs directory.

Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Vincent Donnefort <vdonnefort@google.com>

diff --git a/include/linux/trace_remote.h b/include/linux/trace_remote.h
index 10ca03dc192b..090c58b7d92b 100644
--- a/include/linux/trace_remote.h
+++ b/include/linux/trace_remote.h
@@ -3,10 +3,13 @@
 #ifndef _LINUX_TRACE_REMOTE_H
 #define _LINUX_TRACE_REMOTE_H
 
+#include <linux/dcache.h>
 #include <linux/ring_buffer.h>
 
 /**
  * struct trace_remote_callbacks - Callbacks used by Tracefs to control the remote
+ * @init:		Called once the remote has been registered. Allows the
+ *			caller to extend the Tracefs remote directory
  * @load_trace_buffer:  Called before Tracefs accesses the trace buffer for the first
  *			time. Must return a &trace_buffer_desc
  *			(most likely filled with trace_remote_alloc_buffer())
@@ -22,6 +25,7 @@
  *			new reader-page from the @cpu ring-buffer.
  */
 struct trace_remote_callbacks {
+	int	(*init)(struct dentry *d, void *priv);
 	struct trace_buffer_desc *(*load_trace_buffer)(unsigned long size, void *priv);
 	void	(*unload_trace_buffer)(struct trace_buffer_desc *desc, void *priv);
 	int	(*enable_tracing)(bool enable, void *priv);
diff --git a/kernel/trace/trace_remote.c b/kernel/trace/trace_remote.c
index 039ba71c3b3e..294d051dcef1 100644
--- a/kernel/trace/trace_remote.c
+++ b/kernel/trace/trace_remote.c
@@ -863,6 +863,7 @@ static int trace_remote_init_tracefs(const char *name, struct trace_remote *remo
 int trace_remote_register(const char *name, struct trace_remote_callbacks *cbs, void *priv)
 {
 	struct trace_remote *remote;
+	int ret;
 
 	remote = kzalloc_obj(*remote);
 	if (!remote)
@@ -880,7 +881,11 @@ int trace_remote_register(const char *name, struct trace_remote_callbacks *cbs,
 		return -ENOMEM;
 	}
 
-	return 0;
+	ret = cbs->init ? cbs->init(remote->dentry, priv) : 0;
+	if (ret)
+		pr_err("Init failed for trace remote '%s' (%d)\n", name, ret);
+
+	return ret;
 }
 EXPORT_SYMBOL_GPL(trace_remote_register);
 
-- 
2.53.0.473.g4a7958ca14-goog