[PATCH v19 02/40] dept: add single event dependency tracker APIs

Wrapped the base APIs for easier annotation on wait and event.  Start
with supporting waiters on each single event.  More general support for
multiple events is a future work.  Do more when the need arises.

How to annotate:

1. Initaialize a map for the interesting wait.

   /*
    * Place along with the wait instance.
    */
   struct dept_map my_wait;

   /*
    * Place in the initialization code.
    */
   sdt_map_init(&my_wait);

2. Place the following at the wait code.

   sdt_wait(&my_wait);

3. Place the following at the event code.

   sdt_event(&my_wait);

That's it!

Signed-off-by: Byungchul Park <[email protected]>
---
 include/linux/dept_sdt.h | 65 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 65 insertions(+)
 create mode 100644 include/linux/dept_sdt.h

diff --git a/include/linux/dept_sdt.h b/include/linux/dept_sdt.h
new file mode 100644
index 000000000000..0535f763b21b
--- /dev/null
+++ b/include/linux/dept_sdt.h
@@ -0,0 +1,65 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Single-event Dependency Tracker
+ *
+ * Started by Byungchul Park <[email protected]>:
+ *
+ *  Copyright (c) 2020 LG Electronics, Inc., Byungchul Park
+ *  Copyright (c) 2024 SK hynix, Inc., Byungchul Park
+ */
+
+#ifndef __LINUX_DEPT_SDT_H
+#define __LINUX_DEPT_SDT_H
+
+#include <linux/kernel.h>
+#include <linux/dept.h>
+
+#ifdef CONFIG_DEPT
+#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_request_event(m);					\
+		dept_wait(m, 1UL, _THIS_IP_, __func__, 0);		\
+	} while (0)
+
+/*
+ * sdt_might_sleep() and its family will be committed in __schedule()
+ * when it actually gets to __schedule(). Both dept_request_event() and
+ * dept_wait() will be performed on the commit.
+ */
+
+/*
+ * Use the code location as the class key if an explicit map is not used.
+ */
+#define sdt_might_sleep_start(m)					\
+	do {								\
+		struct dept_map *__m = m;				\
+		static struct dept_key __key;				\
+		dept_stage_wait(__m, __m ? NULL : &__key, _THIS_IP_, __func__);\
+	} while (0)
+
+#define sdt_might_sleep_end()		dept_clean_stage()
+
+#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_, __func__)
+#define sdt_ecxt_exit(m)		dept_ecxt_exit(m, 1UL, _THIS_IP_)
+#define sdt_request_event(m)		dept_request_event(m)
+#else /* !CONFIG_DEPT */
+#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_might_sleep_start(m)	do { } while (0)
+#define sdt_might_sleep_end()		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)
+#define sdt_request_event(m)		do { } while (0)
+#endif
+#endif /* __LINUX_DEPT_SDT_H */
-- 
2.17.1