Date:   Wed,  4 May 2022 17:17:41 +0900
From:   Byungchul Park <byungchul.park@....com>
To:     torvalds@...ux-foundation.org
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Subject: [PATCH RFC v6 13/21] dept: Apply SDT to wait(waitqueue)

Makes SDT able to track dependencies by wait(waitqueue).

Signed-off-by: Byungchul Park <byungchul.park@....com>
---
 include/linux/wait.h |  6 +++++-
 kernel/sched/wait.c  | 16 ++++++++++++++++
 2 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/include/linux/wait.h b/include/linux/wait.h
index 851e07d..e637585 100644
--- a/include/linux/wait.h
+++ b/include/linux/wait.h
@@ -7,6 +7,7 @@
 #include <linux/list.h>
 #include <linux/stddef.h>
 #include <linux/spinlock.h>
+#include <linux/dept_sdt.h>
 
 #include <asm/current.h>
 #include <uapi/linux/wait.h>
@@ -37,6 +38,7 @@ struct wait_queue_entry {
 struct wait_queue_head {
 	spinlock_t		lock;
 	struct list_head	head;
+	struct dept_map		dmap;
 };
 typedef struct wait_queue_head wait_queue_head_t;
 
@@ -56,7 +58,8 @@ struct wait_queue_head {
 
 #define __WAIT_QUEUE_HEAD_INITIALIZER(name) {					\
 	.lock		= __SPIN_LOCK_UNLOCKED(name.lock),			\
-	.head		= LIST_HEAD_INIT(name.head) }
+	.head		= LIST_HEAD_INIT(name.head),				\
+	.dmap		= DEPT_MAP_INITIALIZER(name) }
 
 #define DECLARE_WAIT_QUEUE_HEAD(name) \
 	struct wait_queue_head name = __WAIT_QUEUE_HEAD_INITIALIZER(name)
@@ -67,6 +70,7 @@ struct wait_queue_head {
 	do {									\
 		static struct lock_class_key __key;				\
 										\
+		sdt_map_init(&(wq_head)->dmap);					\
 		__init_waitqueue_head((wq_head), #wq_head, &__key);		\
 	} while (0)
 
diff --git a/kernel/sched/wait.c b/kernel/sched/wait.c
index 9860bb9..d67d0dc4 100644
--- a/kernel/sched/wait.c
+++ b/kernel/sched/wait.c
@@ -104,6 +104,7 @@ static int __wake_up_common(struct wait_queue_head *wq_head, unsigned int mode,
 		if (flags & WQ_FLAG_BOOKMARK)
 			continue;
 
+		sdt_event(&wq_head->dmap);
 		ret = curr->func(curr, mode, wake_flags, key);
 		if (ret < 0)
 			break;
@@ -267,6 +268,9 @@ void __wake_up_pollfree(struct wait_queue_head *wq_head)
 		__add_wait_queue(wq_head, wq_entry);
 	set_current_state(state);
 	spin_unlock_irqrestore(&wq_head->lock, flags);
+
+	if (state & TASK_NORMAL)
+		sdt_wait_prepare(&wq_head->dmap);
 }
 EXPORT_SYMBOL(prepare_to_wait);
 
@@ -285,6 +289,10 @@ void __wake_up_pollfree(struct wait_queue_head *wq_head)
 	}
 	set_current_state(state);
 	spin_unlock_irqrestore(&wq_head->lock, flags);
+
+	if (state & TASK_NORMAL)
+		sdt_wait_prepare(&wq_head->dmap);
+
 	return was_empty;
 }
 EXPORT_SYMBOL(prepare_to_wait_exclusive);
@@ -330,6 +338,9 @@ long prepare_to_wait_event(struct wait_queue_head *wq_head, struct wait_queue_en
 	}
 	spin_unlock_irqrestore(&wq_head->lock, flags);
 
+	if (!ret && state & TASK_NORMAL)
+		sdt_wait_prepare(&wq_head->dmap);
+
 	return ret;
 }
 EXPORT_SYMBOL(prepare_to_wait_event);
@@ -351,7 +362,9 @@ int do_wait_intr(wait_queue_head_t *wq, wait_queue_entry_t *wait)
 		return -ERESTARTSYS;
 
 	spin_unlock(&wq->lock);
+	sdt_wait_prepare(&wq->dmap);
 	schedule();
+	sdt_wait_finish();
 	spin_lock(&wq->lock);
 
 	return 0;
@@ -368,7 +381,9 @@ int do_wait_intr_irq(wait_queue_head_t *wq, wait_queue_entry_t *wait)
 		return -ERESTARTSYS;
 
 	spin_unlock_irq(&wq->lock);
+	sdt_wait_prepare(&wq->dmap);
 	schedule();
+	sdt_wait_finish();
 	spin_lock_irq(&wq->lock);
 
 	return 0;
@@ -388,6 +403,7 @@ void finish_wait(struct wait_queue_head *wq_head, struct wait_queue_entry *wq_en
 {
 	unsigned long flags;
 
+	sdt_wait_finish();
 	__set_current_state(TASK_RUNNING);
 	/*
 	 * We can check for list emptiness outside the lock
-- 
1.9.1

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