linux-kernel - [PATCH RFC v7 03/23] dept: Add single event dependency tracker APIs

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Message-Id: <1673235231-30302-4-git-send-email-byungchul.park@lge.com>
Date:   Mon,  9 Jan 2023 12:33:31 +0900
From:   Byungchul Park <byungchul.park@....com>
To:     linux-kernel@...r.kernel.org
Cc:     torvalds@...ux-foundation.org, damien.lemoal@...nsource.wdc.com,
        linux-ide@...r.kernel.org, adilger.kernel@...ger.ca,
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Subject: [PATCH RFC v7 03/23] 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 (the simplest way):

1. Initaialize a map for the interesting wait.

   /*
    * Recommand to place along with the wait instance.
    */
   struct dept_map my_wait;

   /*
    * Recommand to 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 <byungchul.park@....com>
---
 include/linux/dept_sdt.h | 72 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 72 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 00000000..2644e77
--- /dev/null
+++ b/include/linux/dept_sdt.h
@@ -0,0 +1,72 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * 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
+
+#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_strong(m)					\
+	do {								\
+		struct dept_map *__m = m;				\
+		static struct dept_key __key;				\
+		dept_stage_wait(__m, __m ? NULL : &__key, _THIS_IP_, __func__, true);\
+	} while (0)
+
+/*
+ * Use the code location as the class key if an explicit map is not used.
+ */
+#define sdt_might_sleep_weak(m)						\
+	do {								\
+		struct dept_map *__m = m;				\
+		static struct dept_key __key;				\
+		dept_stage_wait(__m, __m ? NULL : &__key, _THIS_IP_, __func__, false);\
+	} while (0)
+
+#define sdt_might_sleep_finish()	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_)
+#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_strong(m)	do { } while (0)
+#define sdt_might_sleep_weak(m)		do { } while (0)
+#define sdt_might_sleep_finish()	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