linux-kernel - [RFC 13/14] dept: Separate out SDT(Single-event Dependency Tracker) header

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Date:   Tue, 25 Jan 2022 11:36:43 +0900
From:   Byungchul Park <byungchul.park@....com>
To:     torvalds@...ux-foundation.org, mingo@...hat.com,
        linux-kernel@...r.kernel.org
Cc:     peterz@...radead.org, will@...nel.org, tglx@...utronix.de,
        rostedt@...dmis.org, joel@...lfernandes.org, sashal@...nel.org,
        daniel.vetter@...ll.ch, chris@...is-wilson.co.uk,
        duyuyang@...il.com, johannes.berg@...el.com, tj@...nel.org,
        tytso@....edu, willy@...radead.org, david@...morbit.com,
        amir73il@...il.com, bfields@...ldses.org,
        gregkh@...uxfoundation.org, kernel-team@....com
Subject: [RFC 13/14] dept: Separate out SDT(Single-event Dependency Tracker) header

Now that Dept has already been applied to major synchronization
machanisms e.g. spinlock, wait_for_completion and the like, we can take
advantage of Dept by default if CONFIG_DEPT is on.

However, sometimes we need to manually tag wait/event on places where
Dept hasn't been applied. SDT(Single-event Dependency Tracker) would be
useful in that case to tag those. The usage is like:

1. Initialize dmap in the instance associated to the wait/event.

	sdt_map_init(dmap);

2. Add the following just before the wait.

	sdt_wait(dmap);

3. Add the following just before the event.

	sdt_event(dmap);

For better reference of SDT APIs, separated the APIs from dept.h.

Signed-off-by: Byungchul Park <byungchul.park@....com>
---
 include/linux/dept.h     | 36 --------------------------------
 include/linux/dept_sdt.h | 53 ++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 53 insertions(+), 36 deletions(-)
 create mode 100644 include/linux/dept_sdt.h

diff --git a/include/linux/dept.h b/include/linux/dept.h
index 5a726bf..10ef7fc 100644
--- a/include/linux/dept.h
+++ b/include/linux/dept.h
@@ -504,32 +504,6 @@ struct dept_map_common {
  */
 extern void dept_key_init(struct dept_key *k);
 extern void dept_key_destroy(struct dept_key *k);
-
-#define DEPT_SDT_MAP_INIT(dname)	{ .name = #dname }
-#define DEFINE_DEPT_SDT(x)		\
-	struct dept_map x = DEPT_SDT_MAP_INIT(x)
-
-/*
- * SDT(Single-event Dependency Tracker) APIs
- *
- * In case that one dept_map instance maps to a single event, SDT APIs
- * can be used.
- */
-#define sdt_map_init(m)							\
-	do {								\
-		static struct dept_key __key;				\
-		dept_map_init(m, &__key, 0, #m);			\
-	} while (0)
-#define sdt_map_init_key(m, k)		dept_map_init(m, k, 0, #m)
-
-#define sdt_wait(m)							\
-	do {								\
-		dept_asked_event(m);					\
-		dept_wait(m, 1UL, _THIS_IP_, "wait", 0);		\
-	} while (0)
-#define sdt_ecxt_enter(m)		dept_ecxt_enter(m, 1UL, _THIS_IP_, "start", "event", 0)
-#define sdt_event(m)			dept_event(m, 1UL, _THIS_IP_, "event")
-#define sdt_ecxt_exit(m)		dept_ecxt_exit(m, _THIS_IP_)
 #else /* !CONFIG_DEPT */
 struct dept_task { };
 struct dept_key  { };
@@ -563,15 +537,5 @@ struct dept_map_common {
 #define dept_asked_event_split_map(me, mc)		do { } while (0)
 #define dept_key_init(k)				do { (void)(k); } while (0)
 #define dept_key_destroy(k)				do { (void)(k); } while (0)
-
-#define DEPT_SDT_MAP_INIT(dname)
-#define DEFINE_DEPT_SDT(x)
-
-#define sdt_map_init(m)					do { } while (0)
-#define sdt_map_init_key(m, k)				do { (void)(k); } while (0)
-#define sdt_wait(m)					do { } while (0)
-#define sdt_ecxt_enter(m)				do { } while (0)
-#define sdt_event(m)					do { } while (0)
-#define sdt_ecxt_exit(m)				do { } while (0)
 #endif
 #endif /* __LINUX_DEPT_H */
diff --git a/include/linux/dept_sdt.h b/include/linux/dept_sdt.h
new file mode 100644
index 0000000..32a4a9e
--- /dev/null
+++ b/include/linux/dept_sdt.h
@@ -0,0 +1,53 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Dept Single-event Dependency Tracker
+ *
+ * Started by Byungchul Park <max.byungchul.park@...il.com>:
+ *
+ *  Copyright (c) 2020 LG Electronics, Inc., Byungchul Park
+ */
+
+#ifndef __LINUX_DEPT_SDT_H
+#define __LINUX_DEPT_SDT_H
+
+#ifdef CONFIG_DEPT
+
+#include <linux/dept.h>
+
+#define DEPT_SDT_MAP_INIT(dname)	{ .name = #dname }
+#define DEFINE_DEPT_SDT(x)		\
+	struct dept_map x = DEPT_SDT_MAP_INIT(x)
+
+/*
+ * SDT(Single-event Dependency Tracker) APIs
+ *
+ * In case that one dept_map instance maps to a single event, SDT APIs
+ * can be used.
+ */
+#define sdt_map_init(m)							\
+	do {								\
+		static struct dept_key __key;				\
+		dept_map_init(m, &__key, 0, #m);			\
+	} while (0)
+#define sdt_map_init_key(m, k)		dept_map_init(m, k, 0, #m)
+
+#define sdt_wait(m)							\
+	do {								\
+		dept_asked_event(m);					\
+		dept_wait(m, 1UL, _THIS_IP_, "wait", 0);		\
+	} while (0)
+#define sdt_ecxt_enter(m)		dept_ecxt_enter(m, 1UL, _THIS_IP_, "start", "event", 0)
+#define sdt_event(m)			dept_event(m, 1UL, _THIS_IP_, "event")
+#define sdt_ecxt_exit(m)		dept_ecxt_exit(m, _THIS_IP_)
+#else /* !CONFIG_DEPT */
+#define DEPT_SDT_MAP_INIT(dname)
+#define DEFINE_DEPT_SDT(x)
+
+#define sdt_map_init(m)					do { } while (0)
+#define sdt_map_init_key(m, k)				do { (void)(k); } while (0)
+#define sdt_wait(m)					do { } while (0)
+#define sdt_ecxt_enter(m)				do { } while (0)
+#define sdt_event(m)					do { } while (0)
+#define sdt_ecxt_exit(m)				do { } while (0)
+#endif
+#endif /* __LINUX_DEPT_SDT_H */
-- 
1.9.1