tracing: Add init callback to trace remotes

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

Link: https://patch.msgid.link/20260309162516.2623589-9-vdonnefort@google.com
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Vincent Donnefort <vdonnefort@google.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

diff --git a/include/linux/trace_remote.h b/include/linux/trace_remote.h
index 10ca03dc192be34e542b3d002529c6cd23ad18f7..090c58b7d92beebf722915e0e436cf3d4f139cc3 100644 (file)
--- 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 039ba71c3b3e4765704f00d76d84ef65cf095c4d..294d051dcef1d494d9ae77d2d81a24280eb87c10 100644 (file)
--- a/kernel/trace/trace_remote.c
+++ b/kernel/trace/trace_remote.c
@@ -863,6 +863,7 @@ err:
 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);