linux-kernel - [PATCH v3 2/5] tracepoint: Support tterating tracepoints in a loading module

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Message-Id: <172397778740.286558.15781131277732977643.stgit@devnote2>
Date: Sun, 18 Aug 2024 19:43:07 +0900
From: "Masami Hiramatsu (Google)" <mhiramat@...nel.org>
To: Steven Rostedt <rostedt@...dmis.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
	don <zds100@...il.com>,
	linux-kernel@...r.kernel.org,
	linux-trace-kernel@...r.kernel.org,
	mhiramat@...nel.org
Subject: [PATCH v3 2/5] tracepoint: Support tterating tracepoints in a loading module

From: Masami Hiramatsu (Google) <mhiramat@...nel.org>

Add for_each_tracepoint_in_module() function to iterate tracepoints in
a module. This API is needed for handling tracepoints in a loading
module from tracepoint_module_notifier callback function.
This also update for_each_module_tracepoint() to pass the module to
callback function so that it can find module easily.

Signed-off-by: Masami Hiramatsu (Google) <mhiramat@...nel.org>
---
 Changes in v3:
  - Newly added.
---
 include/linux/tracepoint.h |   17 +++++++++++++++--
 kernel/tracepoint.c        |   37 +++++++++++++++++++++++++++++--------
 2 files changed, 44 insertions(+), 10 deletions(-)

diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h
index 837fcf8ec0d5..93a9f3070b48 100644
--- a/include/linux/tracepoint.h
+++ b/include/linux/tracepoint.h
@@ -64,8 +64,13 @@ struct tp_module {
 bool trace_module_has_bad_taint(struct module *mod);
 extern int register_tracepoint_module_notifier(struct notifier_block *nb);
 extern int unregister_tracepoint_module_notifier(struct notifier_block *nb);
-void for_each_module_tracepoint(void (*fct)(struct tracepoint *, void *),
+void for_each_module_tracepoint(void (*fct)(struct tracepoint *,
+					struct module *, void *),
 				void *priv);
+void for_each_tracepoint_in_module(struct module *,
+				   void (*fct)(struct tracepoint *,
+					struct module *, void *),
+				   void *priv);
 #else
 static inline bool trace_module_has_bad_taint(struct module *mod)
 {
@@ -82,10 +87,18 @@ int unregister_tracepoint_module_notifier(struct notifier_block *nb)
 	return 0;
 }
 static inline
-void for_each_module_tracepoint(void (*fct)(struct tracepoint *, void *),
+void for_each_module_tracepoint(void (*fct)(struct tracepoint *,
+					struct module *, void *),
 				void *priv)
 {
 }
+static inline
+void for_each_tracepoint_in_module(struct module *mod,
+				   void (*fct)(struct tracepoint *,
+					struct module *, void *),
+				   void *priv)
+{
+}
 #endif /* CONFIG_MODULES */
 
 /*
diff --git a/kernel/tracepoint.c b/kernel/tracepoint.c
index bed4aad36d92..8879da16ef4d 100644
--- a/kernel/tracepoint.c
+++ b/kernel/tracepoint.c
@@ -736,24 +736,45 @@ static __init int init_tracepoints(void)
 }
 __initcall(init_tracepoints);
 
+/**
+ * for_each_tracepoint_in_module - iteration on all tracepoints in a module
+ * @mod: module
+ * @fct: callback
+ * @priv: private data
+ */
+void for_each_tracepoint_in_module(struct module *mod,
+				   void (*fct)(struct tracepoint *tp,
+				    struct module *mod, void *priv),
+				   void *priv)
+{
+	tracepoint_ptr_t *begin, *end, *iter;
+
+	lockdep_assert_held(&tracepoint_module_list_mutex);
+
+	if (!mod)
+		return;
+
+	begin = mod->tracepoints_ptrs;
+	end = mod->tracepoints_ptrs + mod->num_tracepoints;
+
+	for (iter = begin; iter < end; iter++)
+		fct(tracepoint_ptr_deref(iter), mod, priv);
+}
+
 /**
  * for_each_module_tracepoint - iteration on all tracepoints in all modules
  * @fct: callback
  * @priv: private data
  */
-void for_each_module_tracepoint(void (*fct)(struct tracepoint *tp, void *priv),
+void for_each_module_tracepoint(void (*fct)(struct tracepoint *tp,
+				 struct module *mod, void *priv),
 				void *priv)
 {
 	struct tp_module *tp_mod;
-	struct module *mod;
 
 	mutex_lock(&tracepoint_module_list_mutex);
-	list_for_each_entry(tp_mod, &tracepoint_module_list, list) {
-		mod = tp_mod->mod;
-		for_each_tracepoint_range(mod->tracepoints_ptrs,
-			mod->tracepoints_ptrs + mod->num_tracepoints,
-			fct, priv);
-	}
+	list_for_each_entry(tp_mod, &tracepoint_module_list, list)
+		for_each_tracepoint_in_module(tp_mod->mod, fct, priv);
 	mutex_unlock(&tracepoint_module_list_mutex);
 }
 #endif /* CONFIG_MODULES */